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ELMB-DAC

1. References 1 Embedded Local Monitor Board CERN May 2000 http atlasinfo cern ch ATLAS GROUPS DAQTRIG DCS ELMB elmb html 2 H Boterenbrood CANopen high level protocol for CAN bus Version 3 0 NIKHEF Amsterdam 20 March 2000 http www nikhef nl pub departments ct po doc CANopen30 pdf 3 H Boterenbrood Software for the ELMB CANopen module Version 1 5 NIKHEF Amsterdam 10 January 2002 http www nikhef nl pub departments ct po doc ELMB 15 pdf 4 Low Power Quad 12 bit Voltage Output DAC with Serial Interface MAXIM product datasheet 19 1098 Rev 1 Dec 1996 http www maxim ic com 10 DAC module for the ELMB v1 0 3 May 2002 Appendix A MAX525 DAC A brief description taken from the manufacturer s website Description The MAX525 combines four low power voltage output 12 bit digital to analog converters DACs and four precision output amplifiers in a space saving 20 pin package In addition to the four voltage outputs each amplifier s negative input is also available to the user This fa cilitates specific gain configurations remote sensing and high output drive capacity making the MAX525 ideal for industria process control applications Other features include software shutdown hardware shutdown lockout an active low reset which clears all registers and DACs to zero a user programmable logic output and a serial data output Each DAC has a double buffered input organized as an input
2. COST ESTIMATE ccccccccscccscccscscscccssccssscssscssscssscssssssscssscssccscscees 12 APPENDIX C SCHEMATICS e eeeoeoeoeoeoeseooseoeseseseseseoeseseoeoeseseseseseseseseseoesesesssesesssssssso 13 DAC module for the ELMB v1 0 3 May 2002 1 Introduction This document describes the ELMB DAC Digital to Analog Converter module and how to use it The ELMB DAC is a genera purpose DAC module but was developed specifically to provide analog output capabilities to the ELMB module 1 plugged on its standard Moth erboard It connects directly to the 20 pin J8 connector of this motherboard Up to four ELMB DACs can be connected to and powered by one ELMB The PCB of the ELMB DAC can be fitted in a green box in the same way as an ELMB Motherboard does All connectors are located at the front of the PCB The standard CANopen 1 software for the ELMB motherboard ELMBio version 3 5 3 supports up to four ELMB DACS thus providing a total of 64 12 bit analog output chan nels Both current or voltage output is possible The ELMB DAC can be used in other systems and by other controllers non ELMB as well since it is controlled through a simple serial interface 3 wire plus a select signal 2 Hardware Description Summary 16 channels 12 bit using four 12 bit 4 channel MAX525 ICs 4 and also see Appendix A MAX525 digitally daisy chained Two different versions of MAX525 are available MAX525A with 0 5 LSB Integ
3. it means a maximum of up to 100 DAC channel updates per second can be achieved Having 64 channels this means less than 2 updates per second per channel Because of this it is recommended to use the CANopen SDO message mechanism con firmed instead of the PDO mechanism unconfirmed when using the ELMB CAN open See section 3 for details A new DAC channel setting should not be issued before the previous setting has been con firmed This way it is guaranteed that no settings are lost Actually the host can run one mes sage ahead since the ELMB can buffer one message currently in a next version of the ELMB software this situation will be improved Without or with faster optocouplers the ELMB would be able to sustain a DAC channel up date rate of about 10 KHz as compared to 100 Hz with the currently installed optocouplers DAC module for the ELMB v1 0 3 May 2002 4 Setting a DAC channel Users who intend to use the ELMB DAC by a direct connection to the serial interface are re ferred to the MAX525 datasheet 4 for details on operating the serial interface Be aware of the fact that the DAC module has four MAX525 DACs daisy chained For example to write something to the last DAC in the chain write the required MAX525 command followed by 3 socalled NOP No Operation commands The ELMB software distribution contains functions for accessing the ELMB DAC and could be used as example Using the ELMB and the ELMBio CANope
4. register followed by a DAC reg ister A 16 bit serial word loads data into each input DAC register The serial interface is com patible with SPITM OSPITM and Microwire It allows the input and DAC registers to be updated independently or simultaneously with a single software command The DAC registers can be simultaneously updated via the 3 wire serial interface All logic inputs are TTL CMOS logic compatible Key Features and Specifications Features e Four 12 Bit DACs with Configurable Output Amplifiers e 5V Single Supply Operation Low Supply Current 85mA Normal Operation 10uA Shutdown Mode Available in 20 Pin SSOP Power On Reset Clears all Registers and DACs to Zero Capable of Recalling Last State Prior to Shutdown SPI QSPI and Microwire Compatible Simultaneous or Independent Control of DACs via 3 Wire Serial Interface User Programmable Digital Output Specifications 11 DAC module for the ELMB v1 0 3 May 2002 Functional Diagram DOUT CL TOL DGND AGND Yoo REFAB 16 BIT SHIFT REGISTER E OONTROL FS DN SCK UPO REFCD Appendix B Cost Estimate Assuming a production series of 100 pieces a preliminary price estimate of the ELMB DAC is given in Table 4 It amounts to CHF 17 50 per analog output channel pur O Or pe ER Table 4 ELMB DAC cost prices in CHF Prices marked with are still uncertain Major part of semiconducto
5. C module for the ELMB v1 0 3 May 2002 5 Connectors and Jumpers In Figure 3 pictures of the module s front and backside are shown with connectors jumpers etc indicated Pin 1 External Power Vg Connector Analog Out Connector Digital in Connector Socket for DIL resistor package Socket for 4 iet kee A etet i channel 8 15 LN NM EN M NS E NE ee CEEEELEIB CEIITEITI package channel 0 7 C m em Address Selection Jumper Block from bottom to top CS0 CS1 CS2 CS3 and CS4 resp Power Selection Jumper Block for output circuits from bottom to top 2 jumpers for chan 0 3 2 jumpers for chan 4 7 2 jumpers for chan 8 11 2 jumpers for chan 12 15 shown here all channels take power from Vg connector if jumper installed channel 0 3 powered by Vg channel 0 3 powered by 5V on dig ital in connector Figure 3 Front and backside of the ELMB DAC module DAC module for the ELMB v1 0 3 May 2002 Table 2 presents the layout of the pins of the digital in connector and Table 3 of the analog out connector e Gees HO 9 permmeei women DGD in SO 5 ea in a ES rer ed onion Sv Table 2 ELMB DAC digital in connector pin description ieee ee Se Se ee ee ee wws Ed a poa rer omeced 6 s aoo O E Table 3 ELMB DAC analog out connector pin description DAC module for the ELMB v1 0 3 May 2002
6. DAC module for the ELMB v1 0 3 May 2002 ELMB DAC 16 channel 12 bit DAC module for the ELMB user manual version 1 0 3 May 2002 J aap Kuijt Paul Timmer Bjorn Hallgren Piet de Groen Daniel Tascon Lopez Sander Schouten Henk Boterenbrood NIB Er Amsterdam NL Table of Contents 1 INTRODUCTION isisiccscscccccccc ccccdsscciscsessccectesccsecteststecsescssecssscstecssssssecsscctecsessssecsessstecssesss 2 2 HARDWARE DESCRIPTION ccccccccscscscsssssssssssssssccccscsccscecssscssesesscscssssscsssssssssssssoes 2 3 SPEED OF OPERATION sisccsssccscscscciticescsdecdescctecccsscesncucccebaacsesdsndedessencesccesncvdccadooesoccsncvave 5 4 SETTING A DAC CHANNEL ccccccccscsssscssccssssccescccscccssccsscesscesssescccsscesscesecesscesscsssces 6 5 CONNECTORS AND JUMPERS cccccccscscscssssssssssssssscccecssesscesesesesecssscscsssssssssseseseses 8 REFERENCES oii sccccdccccccsccdsctdscccoscesacescccsdesesccssccesdescccoscesscosccdsdoconcesscssadsccecoschsadedccssdesencsesscesces 10 APPENDIX A MAX525 DAC e eoeoeoeseoeseoeseoeseoeseoeseoeseoeseoeseoeseosseseseseseseseoesssesssssesssssssso 11 DESCRIPTION igus 11 KEY FEATURES AND SPECIFICATIONS cccssccccccescececcecceccccesceccccseeceasseeccasseeccasneeceaaeneeees 11 FUNCTIONAL DIAGRAM cccccssccccsscccsscccssccccsscecsecccssceceecceuscccessseauececsncceuesseuaeceeseeeuecceuseceaens 12 APPENDIX B
7. LMB DAC Note the jumper block used to set a module address and the jumper selecting the power for the current output circuitry Be ware it is always necessary to use a separate external powersupply Vg for 0 20 mA current output an ELMB is not capable to supply enough current The external powersupply voltage Vg can be in the range of 5V to 30V but some care must be taken to protect the output circuit from overdissipation The dissipation in the output FET should be limited to ca 200 mW FET datasheet 600 mW max So for output current 20mA the voltage across the FET should not exceed 200mW 20mA 10V The dissipation D in the FET is described by the following formula D I Vg 2 2 Watts This means that either Ve lt 12 2V or that the external load has a voltage drop of at least Vg 12 2 Volts or in other words represent a minimum load of Vg 12 2 20 KQ For example for a 15V powersupply the output load should be at least 2 8 20 KQ 140 Q So for supply voltages of about 12V and higher a minimum load is required if 20 mA output current is used For 1 mA output current no minimum load is required Table 1 summarizes the load requirements of the ELM B DAC module Output Min Load Max Load mA kQ kQ 0 20 mA Vg 12 2 20 Vg 2 2 20 lma 0 Ve 2 2 Table 1 ELMB DAC load requirements per channel When an ELMB powers the ELMB DAC Vg 5V i e max load at 1 mA is 2 8 KQ The DOUT signal is not essential it c
8. an only serve as a data echo and the optocoupler for this signal could be left uninstalled Figure 2 shows how 4 ELMB DACs can be connected to an ELMB Motherboard system DAC module for the ELMB v1 0 3 May 2002 Digital In Power VD VA i DIN Vref SCLK CS2 fo of CS47 Ee iaddress P DOUT optional VA 5V VD 3 3V VE 5V to 30V 0 20 0 1 mA EE wool ewe Figure 1 Blockdiagram of the 16 channel ELMB DAC In blue digital signals in red power The R s are the optional precision resistors for generating analog voltage outputs Onboard connectors are shown as DAC module for the ELMB v1 0 3 May 2002 SCLK DIN DOUT 4 CS power analog out analog out analog out analog out chan 0 15 chan 16 31 chan 32 47 chan 48 63 Figure2 An ELMB Motherboard system with 4 ELMB DACS providing 64 analog output channels to the ELMB application The select signal jumper block is shown d note the different setting on the individual ELMB DACS which is essential when ELMB DACS are daisy chained 3 Speed of Operation The serial interface of the MAX525 DAC chip can be operated at a clock rate of up to 10 MHz but due to the low power slow optocouplers used in the board design the speed at which the serial interface can be operated is very limited the bit frequency cannot exceed 6 kHz or thereabouts In practice with four MAX525 daisy chained
9. n application 3 as the controller of the ELMB DACs there are 2 methods of setting DAC channels 1 by a socalled PDO Process Data Object message which is an unconfirmed message with no protocol overhead or 2 by a socalled SDO Service Data Object message which is a confirmed message the user is the SDO client and the ELMB is the SDO server Both methods are illustrated by an example Assume the user has an ELMB DAC with 0 1 mA output and he wants to set DAC channel 13 to 0 5 mA half way the 12 bits data range i e write value Ox7FF to the DAC Using the PDO method the user would send the following message to the ELMB User ELMBio RPDO2 COB ID DataByte 0 DataByte 2 3 Channel Number DAC value 0x300 NodeID Ox7FF in which RPDO stands for Receive PDO the CANopen application is a receiver of this PDO and Nodeld is the CAN node identifier switch setting on the ELMB There is no reply to this message a PDO is unconfirmed It is the CANopen method of fast data transport in which the message content has been predefined and agreed upon by sender and receiver s The SDO method is the CANopen way to access the ELMB s Object Dictionary basically a table containing all parameters settings and I O points of the CANopen node ELMB on the basis of an index and a sub index The one accessing the table is the client here the user and the owner of the table here the ELMB is the server Using the SDO method the use
10. r would send the following SDO client message to the ELMB DAC module for the ELMB v1 0 3 May 2002 User ELMBio DataByte COB ID Cone om Dinbi EEE 0x600 0x2B 0x11 0x64 OxOE OxFF 0x07 0x00 0x00 6 E A in which the following numbers can be recognized byte 0 socalled SDO Command Specifier here signifying data download of 2 bytes byte 1 2 the CANopen Object Dictionary Index 0x6411 byte 3 the CANopen Object Dictionary Sub Index here channel number plus 1 byte 4 5 the DAC value LSB first and Nodeld is the CAN node identifier switch setting on the ELMB After the DAC channel value has been written to the the ELMB DAC the ELMB will send the following SDO server reply message letting the SDO client user know that the operation succeeded ELMBio User DataByte DIDI TS SEE ee SENEC IESCNN Terre md rr E SSCS Se 0x580 0x60 Oxll 0x64 OxOE 0x00 0x00 0x00 0x00 NodeID For more information about the CANopen message syntax the user is referred to the docu ments about the CANopen protocol 2 and 3 The ELMBio CANopen application supports 64 analog output DAC channels where channel 0 to 15 address the ELMB DAC with jumper CSO installed channel 16 to 31 the ELMB DAC with jumper CS1 installed channel 32 to 47 the ELMB DAC with jumper CS2 installed and finally channel 48 to 63 the ELMB DAC with jumper CS3 installed See Figure 3 in the next section for the location of the jumpers DA
11. r cost determined by the four MAX525B chips 12 v1 0 3 May 2002 DAC module for the ELMB ix C Schematics Append 2 a ee l i o aa V0Dz 0V E TILINI LNd no INSYYND ova gw3 1NdLNO 1N388f5 AASZ O4 bLLNOI sr meme 7 ili E T koe i 5 V Hol FLD jnzpO JNO IL NOILO3T13S H3 Od SONS TH3HI3N SHL WX O3 15 W 8 S001 Z8SLb gOd 33HMIN NOV bE 9r iino PL INOl NOY vin ellas eid amia qNov zi eLnor EL LNO POI ep cis BD INO EOLIDOIRSI A nia P r cane SLY0H c m LELT 5H NOILOI1as ssayday 13 v1 0 3 May 2002 DAC module for the ELMB 4 on the board mes t for 4 channels t ircui DAC and current output c a ES a ee ee eee fb u6 3Ovd LODZ XZI E TILNI SONWIJ3HIS3N3HI WYOYS LSWY gae ZSSsib gOd JaHMIN WN 02 0 3ounos LNAYYNDS O d SWw13 Ant Tr ON3 mz 32 i1iv0j PO 34 runo vo S8iteog tino amp 3 ELNOI 9 kino I1nor SrPllWd 3d SPPIINd 20 SPPIINd Sd MER S8 te28 S 99908 eel REE bYdO M 14
12. ral Nonlinearity or MAX525B with 1 0 LSB Integral Nonlinearity e Controlled through a 3 wire serial interface opto isolated from the controller with HCPL 0731 type optocouplers One of five module select signal selectable by jumper also opto isolated Current output 0 20 mA or 0 1 mA depending on the value of one onboard resistor per channel e Output accuracy depends on the precision of installed resistors i e 1 or 0 1 Space for optional DIL resistor packages in case voltage output is required Power o Optocouplers powered by the 3 3V supplied on the digital connector from the ELMB ca 5 mA o DAC digital circuitry powered by the 5V supplied on the digital connector from the ELMB ca 5 mA o Current output circuitry powered externally via a separate connection to a powersup ply Vz or with restrictions by the 5V supplied from the digital connector from the ELMB selectable by jumpers o Current output 0 20 mA output circuits must be powered by the separate external powersupply Vg 5 to 30V if an ELMB is the controller of the DAC Voltage output ca Vg 2 5 Volts maximum there is also a minimum see below o Current output O1 mA output circuit can be powered either from 5V from the ELMB or an external powersupply If the ELMB is used for powering 5V the voltage output can be ca 2 5V maximum DAC module for the ELMB v1 0 3 May 2002 Figure 1 below shows a blockdiagram of the E

ELMB-DAC

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