Programmer`s Manual Digital Gamma Finder (DGF)
Contents
1. EOL lagging Energy filter low word E0H lagging Energy filter high word EIL leading Energy filter low word E1H leading Energy filter high word Your return value is UretVal It is an array of 6 words If bit 1 of ChanCSRB is 0 only the first word is incorporated into the output data stream by the main code See tables 4 6 in the user manual for the output data structure If the bit is 1 up to six values are incorporated overwriting the XIA PSA value the USER PSA value the GSLT time and the reserved word in the channel header If the run type compresses the standard nine channel header words the number of user 36 return values is reduced accordingly 1 e only 2 words are available in RunTask 0x102 or 0x202 and no words in RunTask 0x103 or 0x203 When entering UserChannel or UserEvent the address register I5 will point to the start of the current event Register usage The user routines may use all computational registers without having to restore them However the secondary register set cannot be used because the XIA interrupt routines use these The usage of the address registers 10 I7 and the associate registers M0 M7 and LO L7 is subject to restrictions These are listed below for the various routines The associate registers L M are preset and guaranteed as follows LO L7 0 MO 0 M1 1 M2 1 M4 0 M5 1 M6 1 M3 and M7 have no guaranteed values UserBegin UserRunInit and UserRunFinish No fu2. ADE dafa enses siir ae enis NEA AE AAE EA AE ANES EEN tas Sage AEA E AESA 28 Control TASKS ia o 30 Appendix A User supplied DSP code ooooonoccnoccconccconocinanonnnoonncconocono nono cconccconoconononncconncnns 34 6 1 A west a catia saris c oe te ceee tpl on oo atl ee a als a legs Cae 34 6 2 The development environment iris cose sect exes eeicistaseea da 34 6 3 Interfacing user code to XIA s DSP Code ministra 34 GA A a EEEO ee 35 O CHIE LOIS ea ier N E A E S E E EEA 38 11 1 Overview This manual is divided into three major sections The first section is a description of the DGF 4C C Library which is currently used by the DGF 4C Viewer Advanced users can build their own user interface using the user accessible functions in the library The second section is a reference guide to program the DGF 4C modules via CAMAC This will be interesting to those users who want to integrate the DGF 4C modules into their own data acquisition system The third section describes those user accessible variables that control the functions of the DGF 4C modules Those advanced and curious users can user this section to better understand the operation of the DGF 4C Additionally this manual also includes instructions on how to write User DSP code The scope of this document is all DGF 4C modules with serial numbers D1100 through D1199 and E1200 through E1299 Modules with serial numbers E1200 through E1299 have 14 bit ADCs as opposed to the 12 bit ADCs on
3. The process is fairly simple The host writes the length of the data block that is to be downloaded into the variable XDATLENGTH Then the data are written to the linear output buffer the address and length of which are given in the variables AOUTBUFFER and LOUTBUFFER Next the user starts a data run and reads the results after the run has ended 38
4. Viewer In general setting the bit activates the option in question Respond to group triggers only Set this bit if you want to control the waveform acquisition for non triggering channels by a triggering master channel For this option to work properly choose one channel as the master and have its Trigger Enable bit set All dependent channels should have their Trigger Enable bit cleared Set bit 0 in all slave channels You should also set it the master channel to ensure equal time of arrivals for the fast trigger signal which is used to halt the FIFOs Measure individual live time Keep this bit cleared when operating with master and slave channels or when making coincidence measurements using single modules Set this bit when measuring independent spectra i e when list mode data are not required 18 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10 Bit 11 Good channel Only channels marked as good will contribute to spectra and list mode data Read always Channels marked as such will contribute to list mode data even if they did not report a hit This is most useful when acquiring induced signal waveforms on spectator electrodes i e electrodes that did not collect any net charge but only saw a transient induced signal Enable trigger Set this bit for channels that are supposed to contribute to an event trigger Trigger positive Set this bit to trigger on a positive slope
5. data to level 1 buffer In this mode data are first being written into a 2048 word deep buffer Results but not traces are written to the list mode buffer This mode is useful when only the results from pulse shape analyses but not the traces are requested Note that since software revision 2 60 the RUNTASK variable determines which buffer is the intermediate buffer in a run Bit 1 9 Reserved Set to 0 13 Bit 10 13 Bit 11 12 Bit 14 15 MODCSRB Bit 0 Bit 1 15 Bitmask for switchbus settings for revision D and revision E DGF 4Cs only These bits are stored in DSP memory but have to be written to the ICSR register by the host computer to set the FET switches for proper trigger line termination Refer to section 9 3 of the DGF User s Manual for application details To terminate the fast trigger bus line with 100 2 set bit 10 of the ICSR To terminate the event trigger dsp trigger bus line with 100 Q set bit 13 of the ICSR Reserved Reserved Module Control and Status Register B This is a bit oriented variable If set user written DSP code is called Reserved Set to 0 MODFORMAT List mode data format descriptor Currently it is not in use SUMDAC RUNTASK The value of this variable controls the SUMDAC digital to analog converter It can be used to set a trigger threshold on either the multiplicity or the sum analog signal from any combination of the four input channels See the user s
6. every run The 3 bytes of a histogram entry BO LSB B1 and B2 are mapped onto two 16 bit words W0 B1 B0 and W1 0x00 B2 in the I O buffer WO occupies the lower memory address and BO and B2 form the least significant bytes of WO W1 Write histogram memory 1 page for modules with serial numbers D1100 through D1199 E1200 and above writes the DSP s main I O buffer into the first page of external memory The target channel is specified by HOSTIO Write histogram memory subsequent pages for modules with serial numbers D1100 through D1199 E1200 and above writes the DSP s main I O buffer into a subsequent page of external memory The page is specified by an internal page counter The page counter is set to zero first page in a ControlTaks 11 and incremented after each ControlTask 11 or 12 The byte organization is the same as described at the end of Control task 10 reserved First ADC Calibration DGF 4C revision D only Subsequent ADC Calibrations DGF 4C revision D only Contact factory for details 33 6 Appendix A User supplied DSP code 6 1 Introduction It is possible for users to enhance the capabilities of the DGF 4C by adding their own DSP code XIA provides an interface on the DSP level and has built support for this into the DGF 4C Viewer The following sections describe the interfaces and support features 6 2 The development environment For the DSP code development XIA uses and recommends versio
7. from a list mode file Table 11 An Example Code Showing How to Access List Mode Data C_Dgf4c_ Acquire Data 0x1100 dummy start a new list mode run while C_Dgf4c_Acquire_Data 0x4000 dummy wait until run has ended C_Dgf4c_ Acquire Data 0x6000 dummy file name_1 store list mode data in a file C_Dgf4c_ Acquire Data 0x3000 dummy file name 2 store energy histogram in a file C_Dgf4c_ Acquire Data 0x5000 listmodewave file name_1 parse list mode file totaltraces 0 for i 0 1 lt 2 i totaltraces listmodewave it 24 sum the total number of traces for the two modules traceposlen long malloc totaltraces 3 4 allocate memory to hold position and length infomation C_Dgf4c_ Acquire Data 0x5001 traceposlen file name_1 locate traces Trace0 unsigned short malloc traceposlen 1 2 allocate memory to hold the first trace Trace0 0 traceposlen 0 position of the first trace Trace0 1 traceposlen 1 length of the first trace C_Dgf4c_ Acquire Data 0x5002 trace0 file name_1 read out the first trace and put it into trace0 12 4 User Accessible Variables User parameters are stored in the data memory space of the on board DSP The organization is that of a linear memory with 16 bit words Subsequent memory locations are indicated by increasing addresses The data memory space as seen by the host computer starts at 0x4000 There
8. manual for the required jumper settings The threshold in volt can be calculated as follows Threshold 32768 SUMDAC 32768 3 0V This variable tells the DGF what kind of run to start in response to a run start request Nine run tasks are currently supported RunTask Mode Trace CHANHEADLEN Capture 0 Slow control run N A N A 256 0x100 Standard list mode Yes 9 257 0x101 Compressed list mode Yes 9 258 0x102 Compressed list mode Yes 4 259 0x103 Compressed list mode Yes 2 512 0x200 Standard fast list mode No 9 513 0x201 Compressed fast list mode No 9 514 0x202 Compressed fast list mode No 4 515 0x203 Compressed fast list mode No 2 769 0x301 MCA mode No N A 14 RunTask 0 is used to request slow control tasks These include programming the trigger filter FPGAs setting the DACs in the system transfers to from the external memory and calibration tasks RunTask 256 0x100 requests a standard list mode run In this run type all bells and whistles are available The scope of event processing includes computing energies to 16 bit accuracy and performing pulse shape analyses for improved energy resolution and better time of arrival measurements Nine words of results including time of arrival energy XIA pulse shape analysis user pulse shape analysis GSLTtimeA GSLTtimeB GSLTtimeC etc are written into the I O buffer for each channel Le
9. offset DAC is incremented in 2048 equal size steps At each DAC setting the DC offset is determined and written into the list mode buffer At the end of the task the list mode buffer holds the following data Its 8192 words are divided up equally amongst the four channels Data for channel 0 occupy the lowest 2048 words followed by data for channel 1 etc The first entry for each channel s data block is for a DAC value of 0 the last entry is for a DAC value of 65504 In between entries the DAC value is incremented in steps of 32 An examination of the results will reveal a linearly rising or falling response of the ADC to the DAC increments The slope depends on the trigger polarity setting 1 e bit 5 of the channel control and status register A 30 ControlTask 4 ControlTask 5 ChanCSRA For very low and very big DAC values the ADC will be driven out of range and an unpredictable but constant response is seen From the sloped parts a user program can find the DAC value that is necessary for a desired ADC offset It is recommended that for unipolar signals an ADC offset of 400 units is chosen For bipolar signals like the induced waveforms from a segmented detector the ADC offset would be 2048 units 1 e midway between 0 and 4095 Note that for revision D modules ADC waveforms are reported as 14 bit numbers ranging from 0 to 16383 Hence the DC offsets should be adjusted to produce readings of 1600 and 8192 counts respec
10. the user code is then activated and processes the data This in situ code testing allows the most control in the debugging process and is more powerful than having to rely on real signal sources 6 3 Interfacing user code to XIA s DSP code When the DSP is booted it launches a general initialization routine to reach a known and useful state As part of this process a routine called UserBegin is executed It is used to communicate addresses and lengths of buffers local to the user code to the host The host finds this information in the USEROUT 16 buffer described in the main section of this document The calling of UserBegin is not maskable All other functions that are part of the user interface will be called only if bit 0 of MODCSRB is set at the time 34 When a run starts the DSP executes a run start initialization during which it will call UserRunInit It may be used to prepare data for the event procesing routines When events are processed by the DSP code it may call user code in two different instances Events are processed one channel at the time For each channel with data UserChannel is called at the end of the processing but before the energy is histogrammed UserChannel has access to the energy the acquired wave form the trace and is permitted one return value This is the routine in which custom pulse shape analysis will be performed After the entire event consisting of data from one to four channels has been proces
11. value of the two parameters FastLength 20 FastGap lt 32 FASTADCTHR This value is used by the DGF 4C Viewer to store the fast trigger threshold in ADC units The DGF 4C module does not use this value For revision D and revision E modules one LSB of this variable corresponds to 4 LSB of the reported waveform data which are 14 bit numbers FASTTHRESH This is the trigger threshold used by the trigger filter FPGA The value relates to a trigger threshold in ADC units through the formula FASTTHRESH FastADCthr FASTLENGTH MINWIDTH This value aids the pile up inspector MinWidth is the minimum duration in sample clock ticks 25ns which the output from the fast filter must spend over threshold Pulses shorter than that will be rejected as noise spikes The recommended setting is MinWidth FastLength FastGap MAXWIDTH This value aids the pile up inspector Max Width is the maximum duration in sample clock ticks 25ns which the output from the fast filter may spend over threshold Pulses longer than that will be rejected as piled up The recommended setting is Max Width FastLength FastGap SignalRiseTime 25ns Note the constraint Max Width lt 256 Setting Maxwidth 0 switches this part of the pile up inspector off Indeed it is recommended to begin with MaxWidth 0 Once the other parameters have been optimized one can use the Max Width cut to improve the pile up rejection at high count rates Maxwidth should be tun
12. within RESETDELAY 25ns clock ticks after the internal event trigger The default value written by the DGF module should not be changed by the user 22 FTPWIDTH The fast trigger pulse which is sent to the multiplicity output has a programmable width set through FTPWidth The pulse width is given in sampling clock periods of 25ns Note the constraint FTPwidth lt 256 This completes the list of values that control the trigger filter FPGAs The following input parameters are used by the DSP program They become active as soon as the first data taking run has been started Only then will the output parameters reflect the changes made to the set of input parameters TRACELENGTH This tells the DSP how many words of trace data to read The action taken XWAIT depends on FIFOlength which is 4096 for all Rev D and Rev E modules If TraceLength lt FIFOlength the DSP will read from the FIFO In that case individual samples are 25ns apart If FIFOlength lt TraceLength the DSP will read from an FPGA register which mirrors the current ADC output In that case individual readings are 75ns apart In addition only post trigger data will be available because the DSP is then reading data in real time rather than data stored in a FIFO TraceLengths greater than FIFOlength are useful only when reading out only one channel In this case it allows acquiring a long trace to measure the exponential decay time of a preamplifier Extra wait stat
13. 1 The 16 bit in COINCPATTERN cover all combinations Setting COINCPATTERN to OxFFFF causes the DGF to accept any hit pattern as valid In the DGF 4C Viewer this variable can be set in the Coincidence Pattern Edit Panel reachable through the Settings tab by clicking on Edit next to the Coinc Pattern entry 16 COINCWAIT Duration of the coincidence time window in 25ns clock ticks The actual coincidence window is 50ns wider than the value determined by COINCWAIT For this feature to work bit no 1 of the ChannelCSRA of the involved channels should be cleared This ensures that the DSP can at the end of the coincidence window suppress further hits reporting by late channels In the DGF 4C Viewer this bit is set or cleared in line 1 ofthe Channel CSRA Edit Panel The line has the title Measure individual live time Make sure it is unchecked so the DSP globally controls FPGA triggering and live time measurements When acquiring long waveforms it may be necessary to delay DSP data reading to ensure that the FIFOs will contain valid data Secondly when using 6 bit decimation in the FPGA the minimum value for COINCWAIT is larger than 1 in all circumstances Use the following formula to determine COINCWAIT COINCWAIT max 1 ceil 1 5 2 Decimation 70 COINCWAIT max COINCWAIT PAFLENGTH TRIGGERDELAY 70 Choose COINCWAIT big enough such that the requirements of all channels in the module are met SYNCHWAIT Controls run start behavio
14. 5 lists the file names needed to initialize two DGF 4C modules Table 5 File Names in All Files All Files File Name All Files 0 CAXIAIDGF4C Firmware dgf4c bin All Files 1 C XIA DGF4C DSP DGF codeE bin All Files 2 C XIA DGF4C Configuration test itx All Files 3 C XIA DGF4C DSP DGFcodeE var All Files 4 C XIA DGF4C DSP DGFcodeE Ist All Files 5 C XTA DGF4C Firmware fdgf4c4d bin All Files 6 C XTA DGF4C Firmware fdgf4c4e bin The global variable array Module _Global_Values also needs to be initialized before C Library functions can be called to start the initialization Table 6 Initialization of Module_Global_ Values Module Global Names Module Global Values NUMBER MODULES 2 CONTROLLER ID 0 0 J73A 1 CC32 2 offline SCSI_BUS 0 CRATE ID 1 CAMAC MASTER 1 1 enable 0 disable FAST CAMAC 0 1 enable 0 disable LAM ENABLE 0 1 enable 0 disable SLOT WAVE 0 24 CAMAC MASTER CONTROLLER SLOT WAVE I SLOT WAVE 2 1 Module 1 sits in slot 1 2 Module 2 sits in slot 2 3 1 2 Boot DGF4C Modules The boot procedure for DGF 4C modules includes the following steps First all the global parameter names should be downloaded by calling function C_Dgf4c Hand Down Names Then function C Dgf4c User Par IO shoul
15. CSRA 0x2400 download MODULE_CSRA to DSP C_Dgf4c User Par IO Global_Data_Values GLOBAL DATA NAMES 0 set user variable ENERGY _RISETIME to 6 0 us User_Var_Values Find_Xact_User_Match ENERGY _RISETIME 6 0 download ENERGY RISETIME to DSP C_Dgf4c User Par IO User_Var_ Values ENERGY_RISETIME 0 3 3 Access spectrum memory or list mode data 3 3 1 Access spectrum memory The MCA spectrum memory is fixed to 32k words 24 bit per channel residing in the external memory The memory is organized into 8 pages of 4k words To read out the spectra to the host each page has first to be transferred from the external memory to the I O data buffer in the DSP memory and then read out by a DMA transfer The Spectrum memory is accessible after a MCA run or a list mode run if histogramming energy is requested The following code in Table 9 is an example of how to start a MCA run and read out the MCA spectrum after the run is finished 10 Table 9 Accessing the spectrum memory start a MCA run dummy is an unsigned 32 bit integer array of any size C_Dgf4c_ Acquire Data 0x1301 dummy gt wait until run has ended while C_Dgf4c_ Acquire Data 0x4000 dummy save MCA spectrum to a file C_Dgf4c_ Acquire Data 0x3301 dummy file name Read out the MCA spectrum and put it to array User_data C_Dgf4c_ Acquire Data 0x7000 User_data 3 3 2 Access li
16. Programmer s Manual Digital Gamma Finder DGF Model DGF 4C Version 3 00 April 2003 X Ray Instrumentation Associates 8450 Central Ave Newark CA 94560 USA Phone 510 494 9020 Fax 510 494 9040 http www xia com Disclaimer Information furnished by XIA is believed to be accurate and reliable However XIA assumes no responsibility for its use or for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under the patent rights of XIA XIA reserves the right to change the DGF product its documentation and the supporting software without prior notice Nn A Recent eae teh E at nec Tal ee eh oe theca a 1 DEFAC CELDAS ltda od dorada 2 2 1 C Dette Hand Down Names aii ia A AA A a Wa esos 2 22 gt RS a aaa a a a cases Ae L E TAES weed 3 23 Kee Das User Pa nineu Maen incite a a E E a 3 24r EDeMe Acquire Dita A 4 29 gt e Derte Sel Current Mod CR idea 5 260 E BO tod e 6 2 7 DGF 4C C Library Compile Options a dass 6 Control DGF 4C Modules via CAMAC sunrise 8 A A eae a aai 8 3 1 1 Initialize Global Variables dd 8 3 1 2 Boot DGE4C MOdUlES A do 9 32 Setting DSP VA ea 10 3 3 Access spectrum memory or list mode data ciciccccseccesctesessescceasssosnts ensgetacevactendssesnenennas 10 3 3 1 ACCESS A A e Id oo e 10 3 3 2 Access LIST mode Mata ession a 11 User Accessible Y aa a dis 13 41 Modu lepar met rs das 13 42x RN 18 43
17. ResumeRun command while 1 C_Dgf4c_ Acquire Data 0x3000 file name_2 store energy histogram In response to a NEW run the DSP will re evaluate all parameter settings which may affect its data taking procedures and the DSP will clear the I O buffer the level 1 buffer and the spectrum 11 memory before beginning the actual data acquisition In the revision D modules this may take up to 4ms When receiving a RESUME run request the DSP assumes that all DGF settings remain unchanged from the previous run It will also refrain from erasing the spectrum memory and will reset the global read and write pointers which is the equivalent of flushing the data buffers without physically zeroing out their contents A RESUME run request is followed by actual data acquisition within about 10pus The DSP code can also create a compressed output data format If the raw data is directed to the level 1 buffer the DSP has access to pulse shapes However only energies and time stamps of the final data are written to the output buffer all other event data are suppressed This allows a more compact output format which helps to reduce the necessary readout bandwidth To access the list mode data after the run is finished the DGF 4C C Library provides several utility routines to parse the list mode data saved in the output file and read out the waveform or energy of each individual trace The code in Table 11 shows how to read waveforms
18. SYNCH to broadcast SYNCH_WAIT or IN_SYNCH to all modules Name in array User_Var_Names see Table 3 to transfer variable values applicable to individual channels of individual modules User_Par_Values is a double precision array containing the parameter values to be transferred For different User Par Name different User Par Values array should be used Totally three User Par Values arrays should be defined All of these three arrays are one dimensional arrays The corresponding relationship between the User_Par_Values array and User_Par_Name is listed in Table 1 Table 1 The Combination of User_Par_Name and User_Par_Values User_Par_Name User Par Values User_Var_Names Name Size Data Type MODULE GLOBAL NAMES Module Global_Values 64 Double precision GLOBAL DATA NAMES Global_Data_ Values 64x24 Double precision SYNCH_WAIT or IN SYNCH Global Data Values 64x24 Double precision Name in array User_Values 64x24x4 Double precision Function description This function downloads or uploads global parameter or user values between the host and the library For those DSP I O parameters this function calls other functions to convert these parameter values to DSP recognizable values or verse versa 2 4 C_Dgf4c_Acquire_Data Function prototype long C_Dgf4c_Acquire_Data long Run_Type unsigned int User_data char file_name Parameter description User data is an unsi
19. The time T is measured in us The two words are computed as follows PREAMPTAUA floor t PREAMPTAUB 65536 t PreampTauA To recovert use t PREAMPTAUA PREAMPTAUB 65536 This ends the block of channel input data Note that there are four equivalent blocks of input channel data one for each DGF 4C input channel We now show the output variables again beginning with module variables and continuing afterwards with the channel variables The output data block begins at the address 0x4100 Note however that this address could change The output data block comprises of 160 words 1 block of 32 is reserved for module data 4 blocks of 32 words each hold channel data DECIMATION The DSP reads this value from the trigger filter FPGA It is a characteristic of the configuration that was downloaded You will find that the available configuration files support decimations of 0 1 2 3 4 5 and 6 REALTIMEA REALTIMEB REALTIMEC The 48 bit real time clock A B C are the high middle and low word respectively The clock is zeroed on power up and in response to a synch interrupt when InSynch was set to 0 prior to the run start This requires the Busy Synch loop 25 to be closed see the discussion above RealTime RealTimeA 6553612 RealTimeB 65536 RealTimeC 25ns RUNTIMEA RUNTIMEB RUNTIMEC The 48 bit run time clock A B C words are as for the RealTime clock This time counter is active only while a data acq
20. ardware blocks that are not directly accessible from the host computer The most prominent tasks are those to set the DACs program the trigger filter FPGAs and read the histogram memory The following is a list of control tasks that will be of interest to the programmer To start a control task set RUNTASK 0 and choose a CONTROLTASK value from the list below Then start a run by setting bit 0 in the control and status register CSR Control tasks respond within a few hundred nanoseconds by setting the RUNACTIVE bit 13 in the CSR The host can poll the CSR and watch for the RUNACTIVE bit to be deasserted All control tasks indicate task completion by clearing this bit Execution times vary considerably from task to task ranging from under a microsecond to 10 seconds Hence polling the CSR is the most effective way to check for completion of a control task Control Task 0 SetDACs Write the gaindac and trackdac values of all channels into the respective DACs Also program the SumDAC Reprogramming the DACs is required to make effective changes in the values of the variables GAINDAC 0 3 TRACKDAC 0 3 and SUMDAC Control Task 1 Connect inputs Close the input relay to connect the DGF electronics to the input connector Control Task 2 Disconnect inputs Open the input relay to disconnect the DGF electronics from the input connector Control Task 3 Ramp offset DAC This is used for calibrating the offset DAC For each channel the
21. are two sets of user accessible parameters 256 words in data memory are used to store input parameters These can and must be set properly by the user application A second set of 160 words is used for results furnished by the DGF 4C module These should not be overwritten As of this writing the start address for the input parameter block is InParAddr 0x4000 and for the output parameter block it is OutParAddr 0x4100 i e the two blocks are contiguous in memory space We provide an ASCII file named DGFcodeE var which contains in a 2 column format the offset and name of every user accessible variable We suggest that user code use this information to create a name gt address lookup table rather than relying on the parameters retaining their address offsets with respect to the start address The input parameter block is partitioned into 5 subunits The first contains 64 data that pertain to the DGF 4C as a whole It is followed by four blocks of 48 words which describe the settings of the four channels Below we describe the module and channel parameters in turn Where appropriate we show how a variable can be viewed using the DGF4C Viewer 4 1 Module parameters MODNUM Logical number of the module This number will be written into the header of the list mode buffer to aid offline event reconstruction MODCSRA Module Control and Status Register A The viewer panel is the Module CSRA Edit Panel This is a bit oriented variable Bit 0 Write
22. at addresses in the DSP data memory fall into the range from 0x4000 to Ox7FFF The word length in data memory is 16 bit If an address falls in the range from 0 to Ox3FFF it points to a location in program memory Here the word lengths are 24 bits USEROUT 16 words of user output data which may be used by user written DSP code AOUTBUFFER Address of the list mode data buffer LOUTBUFFER Number of words in the list mode buffer AECORR LECORR ATCORR LTCORR unused reserved unused reserved Formerly address and length of an array containing coefficients for energy calculations Now these coefficients are calculated in the DSP code from the decay time unused reserved unused reserved Formerly address and length of an array containing coefficients for normalization and time of arrival corrections Now these coefficients are calculated in the DSP code from the decay time 27 HARDWAREID ID of the hardware version HARDVARIANT Variant of the hardware FIFOLENGTH Length of the onboard FIFOs measured in storage locations Rev D and Rev E DGF 4Cs have FIFOs with 4096 locations FIPPIID ID of the FiPPI FPGA configuration FIPPIVARIANT Variant of the FiPPI FPGA configuration INTRFCID ID of the CAMAC interface FPGA configuration INTRFCVARIANT Variant of the CAMAC interface FPGA configuration DSPRELEASE DSP software release number DSPBUILD DSP software build number The following channel variables contain ru
23. cify command options Currently it is only used to specify the channel in an external memory transfer 17 specify the channel when reading untriggered traces specify the channel for baseline measurements XdatLength Length of a data block to be downloaded from the host Use XdatLength 0 as the USERIN U00 UNUSEDA default value for normal operation A block of 16 input variables used by user written DSP code Many unused but reserved data blocks have names of the structure Unn Those unused data blocks which reside in the block of input parameters for each channel are called UNUSEDA and UNUSEDB Only used in Controltask 4 for reading untriggered traces UNUSEDA stores the weight in the geometric weight averaging scheme to remove higher frequency signal and noise components The value is calculated as follows For a given dt in us calculate the integer intdt dt 0 025 Then if intdt gt 11 XWAIT 4 floor intdt 3 4 3 Finally UNUSEDA floor 65536 intdt 3 4 If intdt lt 11 UNUSEDA is ignored 4 2 Channel variables All channel 0 variables end with 0 channel 1 variables end with 1 etc In the following explanations the numerical suffix has been removed Thus e g CHANCSRAO becomes CHANCSRA etc CHANCSRA The control and status register bits switch on off various aspects of the DGF 4C Bit 0 Bit 1 operation see the CCSRAeditPanel reachable through the InstrumentPanel of the DGF 4C
24. clear it for triggering on a negative slope The trigger filter FPGA can only handle positive signals The DGF handles negative signals by inverting them immediately after entering the FPGA GFLT Set this bit if you want to validate or veto events using the front panel GFLT LEMO input When the bit is cleared the GFLT input is ignored When set the event is accepted only if validated To be validated the GFLT input must be a logic 1 no later than an energy filter rise time after the signal arrival and must remain at logic 1 level until a rise time flat top after signal arrival Histogram energies Set this bit to histogram energies from this channel in the on board MCA memory Reserved Set to 0 Reserved Compute constant fraction timing This pulse shape analysis computes the time of arrival for the signal from the recorded waveform The result is stated in units of 1 256 of a sampling period 25ns Time zero is the start of the waveform Enable contribution to multiplicity Any of the four channels can contribute to the multiplicity output at the front panel With this bit one can switch this contribution on or off Bit 12 15 Reserved 19 CHANCSRB Control and status register B Bit 0 If set call user written DSP code Bit 1 If set all words in the channel header except Ndata trigtime and energy will be overwritten with the contents of URETVAL Depending on the run type this allows for 6 2 or 0 user return
25. d be called to initialize the global variable array Module Global Values After that function C_ Dgf4c Hand Down Names should be called to download the file name array All Files Finally function C_Dgf4c_ Boot System should be called to boot the modules The following code is an example of how to boot the DGF 4C modules using the C Library functions Table 7 An Example Code Illustrating How to Boot DGF 4C Modules download module global names C_Dgf4c Hand Down _Names Module Global Names MODULE GLOBAL NAMES download global data names C_Dgf4c Hand Down _Names Global_Data_ Names GLOBAL DATA NAMES download user variable names C_Dgf4c Hand Down Names User_Var_ Names USER VAR NAMES initialize module global values C_Dgf4c_User_ Par IO Module_Global_ Values MODULE GLOBAL VALUES 0 C_Dgf4c Hand Down _Names All Files ALL FILES download file names C_Dgf4c_ Boot _System 0x1F boot DGF 4C modules C_Dgf4c_Set_Current_ModChan 1 0 set current module and channel number 3 2 Setting DSP variables The host computer communicates with the DSP by setting and reading a set of variables called DSP I O variables These variables totally 416 unsigned 16 bit integers sit in the first 416 words of the data memory The first 256 words which stores input variables are both readable and writeable while the remaining 160 words which stores pointers to various data buffers and run
26. ed by observing the main energy peak in the spectrum for fixed time intervals Once the MaxWidth cut is too tight there will be a loss of efficiency in the main peak Setting Max Width to such a value that the efficiency loss in the main peak is acceptable will give the best overall performance in terms of efficiency and pile up rejection PEAKSAMPLE This variable determines at what time the value from the energy filter will be sampled Note that the following formulae depend on the decimation 0 bit decimation PeakSample max 0 SlowLength Slow Gap 7 1 bit decimation PeakSample max 2 SlowLength Slow Gap 4 2 bit decimation PeakSample SlowLength Slow Gap 2 3 bit and higher decimation PeakSample SlowLength Slow Gap 1 If the sampling point is chosen poorly the resulting spectrum will show energy resolutions of 10 and wider rather than the expected fraction of a percent For some parameter combinations PeakSample needs to be varied by one or two units in either direction due to the pipelined architecture of the trigger filter FPGA 21 PEAKSEP This value governs the minimum time separation between two pulses Two pulses that arrive within a time span shorter than determined by PeakSep will be rejected as piled up The recommended value is PeakSep PeakSample 5 If PeakSep gt 33 PeakSep PeakSample 1 Note the constraint 0 lt PeakSep PeakSample lt 7 PAFLENGTH A FIFO control variable that n
27. eeds to be written into the trigger filter FPGA Using the programmable almost full register we can time the waveform capturing thus that by the time the DSP is triggered at the end of the pile up inspection period the data of interest have percolated through to the begin of the FIFO and are available for read out without delay The acquired waveform will start rising from the baseline at a time delay after the beginning of the trace This delay is a quantity that the user will want to set In the DGF 4C Viewer it is called Trace Delay measured in microseconds and is available through the Settings tab The recommended setting for PafLength is PafLength TriggerDelay UserDelay 0 025 8 Note the constraint PafLength lt 4092 Note that PAFLength should be adjusted only in multiples of 4 as the hardware ignores the lower two bits of this value TRIGGERDELAY This is a partner variable to PafLength For all decimations TriggerDelay PeakSample 6 2 Decimation Note that TriggerDelay should be adjusted only in multiples of 4 as the hardware ignores the lower two bits of this value For MCA runs without taking traces trace length 0 TriggerDelay should be 1 RESETDELAY This variable controls the restarting of the FIFO after it was halted to read the waveform When triggers are distributed across channels and modules a halted FIFO is automatically restarted if the trigger filter FPGA does not receive the distributed event trigger
28. es This parameter controls how many extra clock cycles the DSP waits when reading waveform data in real time rather than out of a FIFO memory This occurs when acquiring data in list mode and asking for trace lengths longer than FIFOlength The time between recorded samples is AT 3 XWAIT 25ns XWAIT is used differently when acquiring untriggered traces in a control run with ControlTask 4 In this case the time between recorded samples is AT 3 25ns if XWAIT lt 3 4 25ns if XWAIT 4 5 25ns if XWAIT 5 3 XWAIT 25ns if 5 lt lt XWAIT lt 11 3 XWAIT 25ns if XWAIT gt 11 XWAIT has to be multiple of 4 The following variables affect internal MCA histogramming of the DGF 4C module ENERGYLOW Start energy histogram at ENERGYLOW LOG2EBIN This variable controls the binning of the histogram Energy values are calculated to 16 bits precision The LSB corresponds to 1 16 of a 12 bit ADC unit or 1 4 of a 23 CFDTHR 14 bit ADC for revision E modules The DGFs however do not have enough histogram memory available to record 64k spectra nor would this always be desirable The user is therefore free to choose a lower cutoff for the spectrum EnergyLow and control the binning Observe the following formula to find to which MCA bin a value of Energy will contribute MCAbin Energy EnergyLow 2 Log2Ebin As can be seen Log2Ebin should be a negative number to achieve the correct behaviour At run start
29. gned 32 bit integer array which holds data transferred between the modules and the host Run Type is a 16 bit word whose lower 12 bit specifies either data run type or control_task run type and upper 4 bit specifies actions start stop poll as described below Lower 12 bit 0x100 0x101 0x102 0x103 0x200 0x201 0x202 0x203 0x301 MCA run list mode runs fast list mode runs 0x1 gt 0x15 control task runs 0x3 adjust offsets 0x4 acquire ADC traces Upper 4 bit 0x1000 start new run 0x2000 resume run 0x3000 stop run and automatically store spectrum data 0x4000 poll 0x500x list mode special runs 0x5000 Parse list mode data file 0x5001 Locate list mode traces 0x5002 Read list mode traces 0x5003 Read list mode energies 0x6000 stop list mode run during repeated runs 0x7000 manually read spectrum from module 0x8000 manually read spectrum from a MCA file file_name is a string variable which specifies the name of the output file file_name needs to have complete path Function description This function acquires ADC traces MCA spectrum or list mode data The string variable file_name needs to be specified when stopping a MCA run or list mode run in order to save the MCA spectrum data or list mode data into a file or in those special list mode runs where the file name should point to the saved list mode data file In all other cases file_name can be specified as an empty string The unsigned 32 bit integer array User_data is u
30. l condition This run type does not write data to the I O buffer The module variable MAXEVENTS should be set to zero to avoid early run termination due toa MAXEVENTS exceeded condition The RunTask can be chosen as the run type in the Run tab of the DGF 4C Viewer CONTROLTASK Use this variable to select a control task Consult the control tasks section of this manual for detailed information The control task will be launched when you issue arun start command with RUNTASK 0 MAXEVENTS The module ends its run when this number of events has been acquired In DGF 4C Viewer MAXEVENTS is automatically calculated when a run mode is chosen from the run type pulldown menu The calculation is based on the trace lengths set by the user Set MaxEvents 0 if you want to switch off this feature e g when logging spectra done automatically in an MCA mode run COINCPATTERN When a DGF 4C is operated on its own the user can request that certain coincidence anticoincidence patterns are found for the event to be accepted With four channels there are 16 different hit patterns and each can be individually selected or marked for rejection by setting the appropriate bit in the COINCPATTERN mask Consider the 4 bit hit pattern 1010 The two 1 s indicate that channel 3 MSB and channel 1 have reported a hit Channels 2 and 0 did not The 4 bit word reads as 10 decimal If this hit pattern qualifies as an acceptable event set bit 10 in the COINCPATTERN to
31. lue 28 corresponds to 1 4 of an original ADC unit for 14 bit ADCs or to 1 16 of an original ADC unit for 12 bit ADC units Waveform data are reported as untriggered traces in the Oscilloscope of the DGF4C Viewer cf control task 4 or as triggered traces in the list mode trace display of the DGF4C Viewer during regular data acquisition Revision D and E DGFs report the waveforms in the Oscilloscope as 14 bit numbers and the list mode trace as 16 bit numbers The trigger threshold set by the FASTTHRESH variable is always in units of the 12 bit ADC times the length of the trigger filter measured in 25ns ticks The Ramp Offset DAC control task 3 always reports results in units of the 12 bit ADC The following example may illuminate this Assume a DC offset such that it measures 400 units on the 12 bit ADC Assume a step pulse with a pulse height of 1000 units as measured by the 12 bit ADC Oscilloscope shows baseline at 1600 The pulse step would show as a jump from 1600 to 5600 in the Oscilloscope display Traces acquired in list mode data runs would show a jump from 6400 to 22400 The energy would be reported as 1000 For a trigger filter length of 100ns FastLength 4 and FASTTHRESH 100 the trigger threshold will be 25 units of the 12 bit ADC This value is shown by the DGF4C Viewer as the threshold value in the Settings tab 29 5 Control Tasks The DSP can execute a number of control tasks which are necessary to control h
32. meter values file DSP code I O variable names file and DSP code all variable names file The remaining elements are FIPPI file names for each module All file names should contain the complete path name Note all modules use the same system FPGA and DSP codes but could use different FIPPI files Module_Global Names is a string array containing global variable names which are applicable to all modules e g number of modules in the crate the CAMAC controller type the SCSI number and the CAMAC crate ID etc Module_Global_ Names currently can hold 64 names If less than 64 names are needed which is the current case the remaining names should be defined as empty strings Global Data_Names is a string array containing global variable names which are applicable to each individual module e g module number module CSR coincidence pattern and run type etc Global Data Names currently can hold 64 names If less than 64 names are needed which is the current case the remaining names should be defined as empty strings User_Var_Names is a string array containing variable names which are applicable to individual channels of individual modules e g channel CSR filter rise time filter flat top gain and offset etc User _Var_Names currently can hold 64 names If less than 64 names are needed which is the current case the remaining names should be defined as empty strings Function description This function can be used to download sys
33. n 5 or 6 of the assembler and linker distributed by Analog Devices Both versions are in use at XIA and work fine It may be inconvenient but is unavoidable to program the ADSP 2181 on board processor in assembler rather than in a higher level programming language like C We found that code generated by the C compiler is bloated and consequently runs very slow As the main piece of the code could not be written in C at all we did not burden our design by trying to be compatible with the C compiler Hence using the C compiler is currently not an option With the general software distribution we provide working executables and support files To support user DSP programming we provide files containing pre assembled forms of XIA s DSP code together with a source code file that has templates for the user functions The user templates have to be converted by the assembler and the whole project is brought together by the linker XIA provides a link and a make file to assist the process In the DGF 4C Viewer we provide powerful diagnostic tools to aid code developing and a data interface to exchange data between the host and the user code The DGF 4C Viewer can at any time examine the complete memory content of the DSP and call any variable from any code section by name A particularly useful added feature is the capability to download data in native format into the DSP and pretend that they were just acquired The event processing routine which calls
34. n statistics Again the variable names carry the channel number as a suffix For example the LIVETIME words for channel 2 are LIVETIMEA2 LIVETIMEB2 LIVETIMEC2 Channel numbers run from 0 to 3 LIVETIMEA LIVETIMEB LIVETIMEC Total live time as measured by the trigger filter FPGA of that channel It excludes times during which the FPGA was prevented from sending triggers due to ongoing DSP data reads or when the run was stopped Convert the three LiveTime words into a live time using the formula LiveTime LiveTimeA 6553612 LiveTimeB 65536 LiveTimeC 0 400us FASTPEAKSA The number of events detected by the fast filter is FASTPEAKSB NumEvents FASTPEAKSA 65536 FASTPEAKSB ADCPERDACA Gain variable ADCPERDACB Both words currently unused but reserved 4 3 ADC data The revision E DGF 4C modules employ 14 bit waveform digitizing ADCs while revision D DGF 4C modules employ 12 bit ADCs All modules are operating at 40MSPS Hence the natural units are 25ns for a time step Depending on which DGF 4C modules being used the original waveform data are either 14 bit unsigned numbers ranging from 0 to 16383 or 12 bit unsigned numbers ranging from 0 to 4095 Derived quantities however are reported by the DGF to higher than 12 bit precision Energy values are all reported as unsigned 16 bit numbers and a pulse step covering the full range of the ADC would be reported as having amplitude of 65535 That is an LSB of an energy va
35. nsure upgrade compatibility CHANHEADLEN For each channel that has been read there is a channel header containing energy and auxiliary information ChanHeadLen is the length of this header CHANHEADLEN varies between 2 and 9 words depending on the run type see RUNTASK 26 The event and channel header lengths plus the requested trace lengths determine the maximum logically possible event size The maximum event size is the sum of EventHeadLen and the ChannelHeadLengths plus the TraceLengths for all channels marked as good 1 e which have bit 2 in the ChanCSRA set Example With all four channels marked as good and required trace lengths of 1000 i e 25us the maximum event size will be MaxEventSize EventHeadLen 4 ChanHeadLen 1000 4039 In the last line typical values for EventHeadLen 3 and ChanHeadLen 9 were substituted BufHeadLen equals 6 Thus there is room for at least 2 events in the list mode data buffer which is 8192 words long But there is not enough room in the level 1 buffer which contains only 2048 words Below follow the addresses and lengths of a number of data buffers used by the DSP program The addresses are generated by the assembler linker when creating the executable On power up the DSP code makes these values accessible to the user Note that the addresses will typically change with every new compilation Therefore your code should never assume to find any given buffer at a fixed address Note th
36. nt I O operations as listed in Table 2 Table 2 The Description of Function C_Dgf4c Buffer_IO Type Direction Values VO Operation 0 f Write DSP I O variable values to modules i 1 POPUA wananlenaurs Read DSP I O variable values from modules 1 1 DSP all variable values Read all DSP variable values from modules 0 Save current settings in all modules to a file 2 1 N A Read settings from a file and apply to all modules 0 Values 0 source Extract settings from a file 1 module number Copy settings from a source module to Values 1 source destination modules channel number 3 Values 2 copy extract pattern bit mask Values 3 Values 4 destination channel pattern Function description This function downloads or uploads DSP settings between the host the library and the DGF 4C modules saves DSP settings into a settings file or loads DSP settings from a settings file and applies to all modules present in the system or copies settings from one module to others or extracts settings from a settings file and applies to the modules present in the system 2 7 DGF 4C C Library Compile Options DGF4C C Library can be compiled as either an Igor XOP used in the DGF 4C Viewer or a standalone C Library free of Igor stuff The latter can be used by advanced users to develop their own data acquisition systems The following table lists the required files for these two o
37. or new runs as well as for resumed runs The purpose is to precompute often needed variables and pointers here and make them available to the routines that are being called on an event by event basis The variables in question would be those that depend on settings that may change in between runs UserChannel This function is called for every event and every DGF4C channel for which data are reported and for which bit 0 of the channel CSR_B ChannelCSRB variable has been set It is called after all regular event processing for this channel has finished but before the energy has been histogrammed UserEvent This function is called after all event processing for this particular event has finished It may be used as an event finish routine or for purposes where the event as a whole is to be examined UserRunFinish This routine is called after the run has ended but before the host computer is notified of that fact Its purpose is to update run summary information Global variables UserIn 16 16 words of input data also visible to host UserOut 16 16 words of output data also visible to host When entering UserChannel the following globals have been set by the DSP Atstart Address of Ist word of the ADC trace Tlen Length ofthe ADC trace Energy Pulse height of the event ChanNum Current channel number GSLTtimeA high word middle low word GSLTtimeB of the 40MHz timer GSLTtimeC GSLT arrival time RUNTASK RUNTASK of the current run
38. other modules Modules with serial numbers D1100 through D1199 and E1200 through E1299 have 4k FIFOs which allow storing up to 4096 ADC samples for each channel 2 DGF 4C C Library The DGF 4C C Library contains a group of C functions used to control the DGF 4C modules It can be compiled as either a XOP file currently used by the DGF 4C Viewer or a dynamic link library DLL or static library used by customized user interface or applications The library provides users six functions which can be used to fully control the modules These six functions were described in sections 2 1 to 2 6 Section 2 7 gives the different options of compiling the DGF AC C Library 2 1 C_Dgf4c_Hand_Down_Names Function prototype long C_Dgf4c_Hand_Down_Names char Names char Name Parameter description Name Names A string variable used to direct which set of names to be handed down It can be one of the following four choices ALL FILES MODULE_GLOBAL_ NAMES GLOBAL DATA NAMES or USER VAR NAMES A two dimensional string array containing either the file names or the global parameter names It can be one of the following four sets of names corresponding to the other parameter Name All Files is a string array which has MAX NUMBER OF MODULES 5 elements Currently MAX NUMBER OF MODULES is defined as 24 The first five elements of All Files are the name of system FPGA file DSP code binary file DSP I O para
39. ptions Table 3 Compilation Options of the DGF 4C C Library Compile Option Required Files C source files C header files Library files Standalone C Library boot c camac c camacdll c CC32 c Communication c dgf4c_c c utilities c boot h Camacdll h globals h sharedfiles h utilities h Libec32 h vpcic32d h Winaspi h pcicc32_ni lib pcicc32_ni dll Igor XOP boot c camac c camacdll c CC32 c Communication c dgf4c_c c utilities c dgf4c_iface c dgf4c igor c Degf4cWinCustom re boot h Camacdll h globals h sharedfiles h utilities h Libcc32 h vpcic32d h Winaspi h dgf4c_iface h pcice32_ni lib pcicc32_ni dll The Igor XOP option also needs the following files in the Igor XOP Library provided by WaveMetrics IgorXOP h VCExtraIncludes h Xop h XOPResources h XOPStandardHeaders h XOPSupport h XOPSupportWin h XOPWinMacSupport h XOPSupport x86 lib and IGOR lib 3 Control DGF 4C Modules via CAMAC 3 1 Initializing The DGF 4C C Library has greatly simplified the initialization of DGF 4C modules via CAMAC compared to the previous implementation by XIA using a set of CAMAC commands We describe below how to initialize DGF 4C modules in a CAMAC crate using the functions described in section 2 As an example we assume two DGF 4C modules one revision D and one revision E module sit in slot 1 and 2 respectively The CAMAC controller sits in slo
40. r When set to 0 the module simply starts or resumes a INSYNCH HOSTIO run in response to the corresponding request When set to 1 closing the Busy Synch loop is required For a single module this is accomplished by connecting the Busy output to the Synch input via a Lemo cable If two or more modules are in the system and are to run synchronously a more complex wiring scheme is needed All Busy outputs must lead to the inputs of a multi input OR The result from the OR operation must be fed back to the Synch inputs This kind of set up in connection with Sync Wait 1 will ensure that the last module ready to actually begin data taking will start the run in all modules And the first module to end the run will stop the run in all modules This way it never happens that a multi DGF system is only partially active InSynch is an input output variable It is used in multi DGF systems in which the modules are driven by a common clock When InSynch is 1 the module assumes it is in synch with the other modules and no particular action is taken at run start If this variable is 0 then all system timers are cleared at the beginning of the next data acquisition run RunTask gt 0 Using the Busy Synch loop as described above the timers are reset when the entire system actually starts the run After run start InSynch is automatically set to 1 Clock resetting can occur only if the Busy Synch loop is closed A 4 word data block that is used to spe
41. raction discriminator LOG2BWEIGHT The DGF measures baselines continuously and effectively extracts DC offsets from these measurements The DC offset value is needed to apply a correction to the computed energies To reduce the noise contribution from this correction baseline samples are averaged in a geometric weight scheme The averaging depends on Log2Bweight 24 DC_avg DC DC_avg DC 22LOG2BWEIGHT DC is the latest measurement and DC_avg is the average that is continuously being updated At the beginning and at the resuming of a run DC_ avg is seeded with the first available DC measurement As before the DSP ensures that LOG2BWEIGHT will be negative The noise contribution from the DC offset correction falls with increased averaging The standard deviation of DC_avg falls in proportion to sqrt 2 LOG2BWEIGHT When using a BLCUT value from a noise measurement cf control task 19 the DGF will internally adjust the effective Log2Bweght for best energy resolution up to the maximum value given by LOG2BWEIGHT Hence the Log2Bweight setting should be chosen at low count rates dead time lt 10 Best energy resolutions are typically obtained at values of 3 to 4 and this parameter does not need to be adjusted afterwards U04 Begin of an unused data block PREAMPTAUA High word of the preamplifier exponential decay time PREAMPTAUB Low word of the above The two variables are used to store the preamplifier decay time
42. rough D1199 E1200 and above transfers the first page of external memory into the DSP s data memory The target location in the DSP memory is the main I O buffer beginning at the address contained in AOUTBUFFER The external memory is organized on a channel by channel basis and HOSTIO specifies which channel to transfer This routine is used to read out spectra after a run During a data run each channel fills a 32k spectrum 24 bits deep in the external memory The external memory is organized into 8 pages of 4k words In the control run one 4k x 24 bits page is written into the 8k x 16 bits I O buffer After the control run is finished the host has to read out the I O buffer ControlTask 9 always transfers the first page of a given channel then increments a page counter For subsequent transfers of the remaining 7 pages use ControlTask 10 Read histogram memory subsequent pages for modules with serial numbers D1100 through D1199 E1200 and above transfers a page of external memory into the DSP s main I O buffer An internal page counter specifies the page It is set to zero first page in a ControlTaks 9 and is incremented by the DSP after each ControlTasks 9 or 10 To read out all 8 pages of a channels spectrum first start a run with ControlTask 9 followed by seven runs with ControlTask 10 reading out the 32 ControlTask 11 ControlTask 12 ControlTask 19 ControlTask 20 ControlTask 21 1 O buffer after
43. rt four consecutive runs with ControlTask 4 in the selected module one for each channel ProgramFiPPI Write all relevant data to the FiPPI control registers and download the ADC calibration data The latter must be written into the I O buffer starting at the address given by the variable AOUTBUFFER prior to calling this task If 31 ControlTask 6 ControlTask 9 ControlTask 10 the ADC calibration data are not available fill the first 1024 locations of the T O buffer with zeros Measure Baselines This routine is used to collect baseline values Currently DSP collects six words BOL BOH B1L B1H time stamp and ADC value for each baseline 1365 baselines are collected until the 8192 word I O buffer is almost completely filled The host computer can then read the I O buffer and calculate the baseline according to the formula B1 BIL B1H 65536 2 Manon B0 BOL B0H 65536 20 MATION TAU PreampTauA PreampTauB 65536 Baseline B1 B0 exp 0 025 SlowLength SlowGap 2P MATTON PAY Baseline values can then be statistically analyzed to determine the standard deviation associated with the averaged baseline value and to set the BLCUT BLCUT should be about 3 times the standard deviation Baseline values can also be plotted against time stamp or ADC value to explore the detector performance BLCUT should be set to zero while running ControlTask 6 Read histogram memory 1 page for modules with serial numbers D1100 th
44. rther restrictions but user code must leave the associated registers listed above in exactly this state when exiting UserChannel 15 16 17 These registers may not even temporarily be overwritten because there L5 L6 are interrupt functions which depend on the contents of these registers M0 M1 M2 M4 M5 M6 10 11 13 14 These registers may be altered but must be restored on exit L0 L1 L2 L3 L4 L7 12 These registers may be altered and need not be restored M3 M7 UserEvent 15 16 17 These registers may not even temporarily be overwritten because there L5 L6 are interrupt functions which depend on the contents of these registers M0 M1 M2 M4 M5 M6 14 These registers may be altered but must be restored on exit L0 L1 L2 L3 L4 L7 10 11 12 13 These registers may be altered and need not be restored M3 M7 37 6 5 Debugging tools Besides the debugging tools that are accessible through the DGF 4C Viewer it is also possible to download data into the DGF data buffers and call the event processing routine This allows for an in situ test of the newly written code and allows exploring the valid parameter space systematically or through a Monte Carlo from the host computer For this to work the module has to halt the background activity of continuous base line measuring Next data have to be downloaded and the event processing started When done the host can read the results from the known address
45. sed only for acquiring ADC traces control task 0x4 reading out the list mode traces and energies in those special list mode runs or reading out MCA spectrum In all other cases User_data can be any unsigned integer array with arbitrary size Make sure that the User_data has the correct size and data type before reading out ADC traces list mode traces or energies or MCA spectrum 2 5 C_Dgf4c_Set_Current_ModChan Function prototype long C_Dgf4c Set Current ModChan unsigned short Module unsigned short Channel Parameter description Module is an unsigned 16 bit integer which specifies the current module to be set Module should be in the range of 1 to 23 Channel is an unsigned 16 bit integer which specifies the current channel to be set Channel should be in the range of 0 to 3 Function description This function sets the current module number and channel number 2 6 C_Dgf4c_Buffer_lO Function prototype long C_Dgf4c Buffer IO unsigned short Values unsigned short type unsigned short direction char file_name Parameter description The parameter Values is an unsigned 16 bit integer array used for data transfer between the host and the library The parameter type specifies the I O type The parameter direction indicates the data flow direction The string variable file_name contains the name of the settings file Different combinations of the three parameters Values type direction designate differe
46. sed the function UserEvent may be called It may be used in applications in which data have to be correlated across channels At the end of a run the closing routine may call UserRunFinish typically for updating statistics and similar run end tasks The above mentioned routines are described below including the interface variables and the permissible use of resources 6 4 The interface The interface consists of five routines and a number of global variables Data exchange with the host computer is achieved via two data arrays that are part of the I O parameter blocks visible to the host The total amount of memory available to the user comprises 2048 instructions and 1000 data words Host interface as supported by the DGF4C Viewer UserIn 16 16 words of input data UserOut 16 16 words of output data Interface DSP routines UserBegin This routine is called after rebooting the DSP Its purpose is to establish values for variables that need to be known before the first run may start Address pointers to data buffers established by the user are an example The host will need know where to write essential data to before starting a run Since the DSP program comes up in a default state after rebooting UserBegin will always be called This is different for the routines listed below which will only be called if for at least one channel bit 0 of ChannelCSRB has been set 35 UserRunInit This function is called at each run start f
47. st mode data The list mode data in the linear output data buffer can be written in a number of formats User code should access the three variables BUFHEADLEN EVENTHEADLEN and CHANHEADLEN in the configuration file of a particular run to navigate through the data set There are two data buffers to choose from the linear 8192 words long I O buffer and a circular level 1 data buffer with room for 2048 words The buffer for the raw data is chosen automatically according to the run type Note that because the level 1 buffer is shorter the total amount of trace data that it can accept is limited to about 50us In a multi parametric setup you can do any number of runs in a row The first run would be started as a NEW run This clears all histograms in memory Subsequent runs would complete when the linear data buffer is full Once it has been read out you can RESUME running This keeps the histogram memory intact and you can accumulate spectra over many runs The example code shown in Table 10 illustrates this Table 10 Command sequence for multiple runs in a row C_Dgf4c_ Acquire Data 0x1100 dummy start a new list mode run k 1 initialize counter do while C_Dgf4c_ Acquire Data 0x4000 dummy wait until run has ended C_Degf4c_ Acquire Data 0x6000 dummy file name 1 stop run and save list mode run data k k 1 if k gt Nruns break C_Dgf4c_ Acquire Data 0x2100 dummy issue
48. summary data are only readable The exact location of any particular variable in the DSP code will vary from one code version to another To facilitate writing robust user code we provide a reference table of variable names and addresses with each DSP code version Included with your software distribution is a file called DGFcodeE var It contains a two column list of variable names and their respective addresses Thus you can write your code such that it addresses the DSP variables by name rather than by fixed location It should come as no surprise that many of the DSP variables have meaningful values and ranges depending on the values of other variables A complete description of all interdependencies can be found in Section 4 All of these interdependencies have been taken care of by the DGF 4C C Library So instead of directly setting DSP variables users only need to set the values of the global variables defined in Table 4 The C Library will then convert these values into corresponding DSP variable values and download them into the DSP data memory On the other hand if users want to read out the data memory the C Library will first convert these DSP values into the global variable values The following code is an example of setting DSP variables through the C Library Table 8 An Example Code to Illustrating How to Set DSP Variables set global data variable MODULE_CSRA to 0x2400 Global_Data_Values Find_Xact Global DATA_Match MODULE_
49. t 24 3 1 1 Initialize Global Variables As discussed in section 2 3 we assume that three global variable arrays have been defined Module Global Values Global Data Values and User Values For these three global variable arrays we also need to define three global name arrays Module Global Names Global Data Names and User_Var_ Names Table 4 lists the names for these name arrays The order of placing these names into the name array is not important since the C Library uses search functions to locate each name at run time Table 4 Contents of Global Name Arrays Array Names Module Global Names NUMBER MODULES CONTROLLER ID SCSL BUS CRATE_ID 7 7 CAMAC MASTER FAST CAMAC LAM ENABLE C_ LIBRARY RELEASE C_LIBRARY BUILD SLOT WAVE Global Data Names MODULE_NUMBER MODULE_CSRA MODULE_CSRB MODULE_FORMAT MAX EVENTS COINCIDENCE PATTERN COINCIDENCE WAIT SYNCH_WAIT IN SYNCH RUN_TYPE BUFFER HEAD LENGTH EVENT HEAD LENGTH CHANNEL HEAD LENGTH OUTPUT BUFFER LENGTH NUMBER EVENTS RUN TIME User Var Names CHANNEL_CSRA CHANNEL_CSRB ENERGY_RISETIME Z T ENERGY FLATTOP TRIGGER RISETIME TRIGGER FLATTOP TRIGGER THRESHOLD VGAIN VOFFSET TRACE LENGTH TRACE DELAY PSA_START PSA_END EMIN BINFACTOR TAU BLCUT XDT CFD_THRESHOLD MULTIPLICITY PULSE WIDTH LIVE TIME INPUT COUNT RATE Additionally a string array All_Files containing the file names for the initialization is also needed Table
50. tem file names or user and global names from the host to the DGF 4C C Library 2 2 C_Dgf4c_Boot_System Function prototype long C_Dgf4c_Boot_System long Boot_Pattern Parameter description Boot Pattern is a bit mask Bit 0 Boot system FPGA Bit 1 Boot FIPPI Bit 2 Boot DSP Bit 3 Load DSP parameters Bit 4 Apply DSP parameters call Set_DACs and Program_FIPPI Under most of the circumstances all the above tasks should be executed to initialize the DGF 4C modules i e the Boot Pattern should be Ox1F Function description This function can be used to boot all DGF 4C modules in the system Before booting the modules this function initializes the CAMAC communication port and if CAMAC Master is going to be used loads the CAMAC station number register 2 3 C_Dgf4c_User_Par_lO Function prototype long C_Dgf4c_User_Par_IO double User_Par_Values char User_Par_ Name long direction Parameter description direction 0 download write parameter values from the host to the library 1 upload read parameter values from the library to the host User_Par Name is a string variable which directs what type of parameter values to be transferred User Par Name can be one of the following four choices MODULE GLOBAL NAMES to transfer global variable values applicable to all modules GLOBAL DATA NAMES to transfer global variable values applicable to individual modules SYNCH_WAIT and IN_
51. the DSP program ensures that Log2Ebin is indeed negative by replacing the stored value by abs Log2Ebin The histogramming routine of the DSP takes care of spectrum overflows and underflows This sets the threshold of the software constant fraction discriminator The threshold fraction f is encoded as Round f 65536 with 0 lt f lt 1 PSAOFFSET PSALENGTH When recording traces and requiring any pulse shape analysis by the DSP these two parameters govern the range over which the analysis will be applied The analysis begins at a point PSAOFFSET sampling clock ticks into the trace and is applied over a piece of the trace with a total length of PPALENGTH clock ticks INTEGRATOR unused reserved BLCUT CFDREG This variable sets the cutoff value for baselines in baseline measurements If BLCUT is not set to zero the DSP checks continuously each baseline value to see if it is outside of the limit set by BLCUT If the baseline value is within the limit it will be used to calculate the average baseline value Otherwise it will be discarded Set BLCUT to zero to not check baselines therefore reduce processing time ControlTask 6 can be used to measure baselines Host computer can then histogram these baseline values and determine the appropriate value for BLCUT for each channel according to the standard deviation SIGMA for the averaged baseline value BLCUT could be set to be three times SIGMA Reserved for FPGA based constant f
52. time of arrival energy XIA pulse shape analysis user pulse shape analysis GSLTtimeA GSLTtimeB GSLTtimeC etc are written into the I O buffer for each channel RunTask 513 0x201 requests a compressed fast list mode run without trace capture Both Level 1 buffer and I O buffer are used in this RunTask Nine words of results including time of arrival energy XIA pulse shape analysis user pulse shape analysis GSLTtimeA GSLTtimeB GSLTtimeC etc are written into the I O buffer for each channel RunTask 514 0x202 requests a compressed fast list mode run The only difference between RunTask 514 and 513 is that in RunTask 514 only four words of results 15 time of arrival energy XIA pulse shape analysis user pulse shape analysis are written into the I O buffer for each channel RunTask 515 0x203 requests a compressed fast list mode run The only difference between RunTask 515 and 513 is that in RunTask 515 only two words of results time of arrival and energy are written into the I O buffer for each channel RunTask 769 0x301 requests a MCA run The raw data stream is always sent to the level 1 buffer independent of MODCSRA The data gathering interrupt routine fills that buffer with raw data while the event processing routine removes events after processing If the interrupt routine finds the level 1 buffer to be full it will ignore events until there is again room in the buffer The run will not abort due to buffer ful
53. tively for unipolar and bipolar signals A user program would use the result from the calibration task to find set and program the correct offset DAC values Since the offset measurement has to take the preamplifier offset into account this measurement must be made with the preamplifier connected to the DGF input The control task makes 16 measurements at each DAC step and uses the last computed DC offset value to enter into the data buffer Due to electronic noise it may occasionally happen that none of the sixteen attempts at a base line measurement is successful in which case a zero is returned The user software must be able to cope with an occasional deviation from the expected straight line On exit the task restores the offset DAC values to the values they had on entry Untriggered Traces This task provides ADC values measured on all four channels and gives the user an idea of what the noise and the DC levels in the system are This function samples 8192 ADC words for the channel specified in HOSTIO The XWAIT variable determines the time between successive ADC samples samples are XWAIT 25ns apart In the DGF 4C Viewer XWAIT can be adjusted through the dT variable in the Oscilloscope panel The results are written to the 8192 words long I O buffer Use this function to check if the offset adjustment was successful From the DGF 4C Viewer this function is available through the Oscilloscope Panel Hit the Refresh button to sta
54. uisition run is in progress Comparing the run time with the real time allows judging the overhead due to data readout Compute the run time using the following formula RunTime RunTimeA 6553612 RunTimeB 65536 RunTimeC 25ns GSLTTIMEA GSLTTIMEB GSLTTIMEC Signal arrival time of a logic 0 gt 1 transition at the GSLT front panel LEMO input The time latched is the real time at that moment NUMEVENTSA NUMEVENTSB Number of valid events serviced by the DSP Again the high word carries the suffix A and the low word the suffix B DSPERROR This variable reports error conditions 0 NOERROR no error 1 RUNTYPEERROR unsupported RunType 2 RAMPDACERROR Baseline measurement failed SYNCHDONE This variable can be set to 1 to force the DSP out of an infinite loop caused by a malfunctioning Busy Synch loop when a run start request was issued with SYNCHWAIT 1 BUFHEADLEN At the beginning of each run the DSP writes a buffer header to the list mode data buffer BufHeadLen is the length of that header Currently BUFHEADLEN is 6 but this value should not be hardcoded it should be read from the DSP to ensure upgrade compatibility EVENTHEADLEN For each event in the list mode buffer or the level 1 buffer there is an event header containing time and hit pattern information EventHeadLen is the length of that header Currently EVENTHEADLEN is 3 but this value should not be hardcoded it should be read from the DSP to e
55. values in the channel header Bit2 15 are reserved Set to 0 The following two data words are used to set the on board DACs for this channel Once a new variable has been written to DSP memory the DACs have to be reprogrammed by starting a run with RunTask 0 and ControlTask 0 GAINDAC This DAC is used to program the variable gain amplifier The GainDAC value corresponds to a gain according to the following formula Gain V V 0 1639 10 65535 GAINDAC 32768 TRACKDAC This DAC determines the DC offset voltage The offset can be calculated using the following formula Offset V 3 0 32768 TRACKDAC 32768 U02 Begin of a reserved data block The following block of data contains trigger filter FPGA data Once a new variable has been written to DSP memory it has to be activated by starting a run with RunTask 0 and ControlTask 5 SLOWLENGTH The rise time of the energy filter depends on SlowLength RiseTime SlowLength 2 Decimation 25ns SLOWGAP The flat top of the energy filter depends on SlowGap FlatTop SlowGap 2 Decimation 25ns There is a constraint concerning the sum value of the two parameters SlowLength SlowGap lt 32 FASTLENGTH The rise time of the trigger filter depends on FastLength RiseTime FastLength 25ns Note the constraint FastLength lt 32 FASTGAP The flat top of the trigger filter depends on FastGap FlatTop FastGap 25ns There is a constraint concerning the sum
56. vel 1 buffer is not used in this RunTask RunTask 257 0x101 requests a compressed list mode run Both Level 1 buffer and I O buffer are used in this RunTask but no traces are written into the I O buffer Nine words of results including time of arrival energy XIA pulse shape analysis user pulse shape analysis GSLTtimeA GSLTtimeB GSLTtimeC etc are written into the I O buffer for each channel RunTask 258 0x102 requests a compressed list mode run The only difference between RunTask 258 and 257 is that in RunTask 258 only four words of results time of arrival energy XIA pulse shape analysis user pulse shape analysis are written into the I O buffer for each channel RunTask 259 0x103 requests a compressed list mode run The only difference between RunTask 259 and 257 is that in RunTask 259 only two words of results time of arrival and energy are written into the I O buffer for each channel RunTask 512 0x200 employs the same internal data format as RunTask 256 but omits buffer full checks and trace capture The run is stopped when the required number of events MaxEvents has been acquired This run type uses the shortest possible interrupt routine for raw data gathering Hence it allows for the shortest time between two logged events For best results the channel variables PAFLength and TriggerDelay should be set to 1 for all channels involved Level 1 buffer is not used in this run type Nine words of results including
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