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Automatic Thermal Monitoring System on HPC II

1. print all of the registers within the Thermal Sensor print_adt7461_registers return ct_exec Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 29 Pseudocode TE PR a 2 2 he Ae AEIR Ae 2 2A he IN he 2A EDE ENI 2 2 he EM 2 fee AE 2 AE he EDEA EMERE SEAE AE IE HEINE he 2 AE 2 2 oe hehe 2A 22k dt_exec Auxilliary function for dt command called by par_gme This function displays the current temperature reading from the ADT7461 and displays this value in both hex and Celcius This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 07 29 05 Return void AAJ APD Pe a aE CH A A AC A CCR CA A CCR GC A AC A AC void dt_exec ULONG fb sb first byte and second byte of external temp ULONG lb local temperature byte int sbm second external byte modified to decimal value ULONG da device address for ADT7461 da 0 fb 0 sb 0 lb 0 sbm 0 Select the ADT7461 as the desired device to access on the 2C bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms lb value read from Local Temperature register in Thermal Sensor fb value read from External Temp High Byte register in Thermal Sensor
2. Pseudocode Appendix B Pseudocode This appendix contains the pseudocode examples for all of the functions that make up the ATMS The functions are broken up into the files that contain them see Table 2 for a function hierarchy Full versions of this code are publicly available under license from FSL env c SERIES ICE EEE EEE EEE ACI GIGS IACI AICI AGE A OK as a ako kk ak ak a ok adt7461_init This function initializes all the registers within the ADT7461 thermal monitor to programmer specified values Tt also checks for the TOFFSET environment variable and if found will set the DC offset of the ADT7461 to TOFFSET If TOFFSET is not found it uses a default offset determined by the processor type 47A or 48 This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 9 22 05 Return void IAI ADE HE EE HE ABE AEH 2 EE ICSE oo oo o o ooo k void adt7461_initQ ULONG da device address for Thermal Sensor ULONG temp ULONG envalue environment variable holder char negvalue negative environment variable holder initialize the THERM global variables to 0 on boot up ExtTHERM 0 LocTHERM 0 Select the ADT7461 as the desired device to access on the IC bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set I
3. Date 09 08 05 Return void BE ACH H SESSA ICIS IRS kkk kkk A a ok void check_limits ULONG statusRead ADT7461 status register bits ULONG locTemp extTemp ADT7461 loc and ext thermal values ULONG temp used as temp to write static values int hid1 hidtemp HID register values ULONG da device address for ADT7461 ULONG pwmvalue value for CPU fan register ULONG shutdownTemp critical overheat temperature shutdownTemp 0 pwmvalue 0 da 0 hid1 0 hidtemp 0 temp 0 statusRead 0 Select the ADT7461 as the desired device to access on the 2C bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms locTemp value read from Thermal Sensor Local Temp register extTemp value read from Thermal Sensor External Temp register statusRead value read from Thermal Sensor Status register set critical temperature limit if TSHUTDOWN env variable is defined Automatic Thermal Monitoring System on HPC Il Rev 0 22 Freescale Semiconductor shutdownTemp TSHUTDOWN else shutdownTemp 100degC Critical system threshold already exceeded Shut down system if temperature gt shutdownTemp if locTemp gt shutdownTemp II extTemp gt shutdownTemp PRINT n tCritical overheat temperature detected PRINT n t
4. sb value read from External Temp Low Byte register in Thermal Sensor Only the first two bits of the second byte are used to determine the 25 degree resolution Therefore divide the 8 bits read by 2 56 to get the decimal equivalent we are looking for See 7461 datasheet pg 10 II Ex sb 0b01000000 0x40 or 64 decimal I sb 2 56 64 2 56 25 25 is the degree resolution sbm int float sb 2 56 divide by 2 56 to get decimal digits Automatic Thermal Monitoring System on HPC Il Rev 0 30 Freescale Semiconductor print temperature values to screen stdout PRINT n t Register values hex 0x01 2 2X n 0x10 2 2X fb sb PRINT n t Local Temperature degrees C d 00 Ib PRINT n tRemote Temperature degrees C 2 2d 2 2d n n fb sbm return dt_exec JEA AAE he AE hee Ae AEE E fe AE BEEE SHE HEI E EIEE I EAE E INE NEIRE IE EAE ESEE S 2 E SHEFE he SHE he 2 PEHEN oe AEE ENSHE print_adt7461_registers Function used by ct_exec to print out the registers inside the Thermal Sensor This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 09 02 05 Return void HAJ EEEE A A CC A CRC CR CR AC AC 7 void print_adt7461_registers ULONG da device address for Thermal Sensor ULONG temp temp 0 da 0 S
5. Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 39 How to Reach Us Home Page www freescale com email support freescale com USA Europe or Locations Not Listed Freescale Semiconductor Technical Information Center CH370 1300 N Alma School Road Chandler Arizona 85224 800 521 6274 480 768 2130 support freescale com Europe Middle East and Africa Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen Germany 44 1296 380 456 English 46 8 52200080 English 49 89 92103 559 German 33 1 69 35 48 48 French support freescale com Japan Freescale Semiconductor Japan Ltd Headquarters ARCO Tower 15F 1 8 1 Shimo Meguro Meguro ku Tokyo 153 0064 Japan 0120 191014 81 2666 8080 support japan freescale com Asia Pacific Freescale Semiconductor Hong Kong Ltd Technical Information Center 2 Dai King Street Tai Po Industrial Estate Tai Po N T Hong Kong 800 2666 8080 support asia freescale com For Literature Requests Only Freescale Semiconductor Literature Distribution Center P O Box 5405 Denver Colorado 80217 800 441 2447 303 675 2140 Fax 303 675 2150 LDCForFreescaleSemiconductor hibbertgroup com Document Number AN2929 Rev 0 11 2005 Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductor products There ar
6. arg_getvalue amp token amp test 16 SUCCESS if flag and value are valid place both into their appropriate arrays optstr j b datastr j test jr oop through the number of valid operations indicated by j and perform necessary operations for i 0 i lt j i switch optstr i Set the External THERM limit case t write datastr i to External THERM Limit register Automatic Thermal Monitoring System on HPC Il Rev 0 28 Freescale Semiconductor Pseudocode ExtTHERM datastr i store user changes in order to refresh later break Set the Local THERM limit case o write datastr i to Local THERM Limit register LocTHERM datastr i store user changes in order to refresh later break Set the External Temperature High Limit High Byte case x write datastr i to External Temp High Limit register break Set the Local Temperature High limit case I write datastr i to Local Temperature High Limit register break Set the conversion rate of the ADT7461 case c write datastr i to Conversion Rate register break Set the THERM Hysteresis value case s write datastr i to THERM Hysteresis register break Set the Consecutive ALERT value case r write datastr i to Consecutive ALERT register break Set the Configuration Register value case g write datastr i to Configuration register break default return
7. 0000 7 4 DINK32 on HPC II Board 4 10 4 1 Environment cia wean cd etn ewn ene ete wee E 10 4 2 Command Line Interface 0 i J CONCIUSION cvs vce kon wun eases dee eee dees wee 15 6 References inci siadica cain Garde aia cad dad wate e 15 7 Revision History 0 00 0 cee eee eee eee 16 A Ideality Factor Determination 17 B Psetidocod crcerireri ur eipeienr iian ie ie 19 ey oe 2 freescale semiconductor Functional Overview Section 4 DINK32 on HPC II Board gives some kernel specific instructions for those operating under DINK32 on a HPC II development board Section 5 Conclusion gives closing remarks Section 6 References provides a list of references Section 7 Revision History gives the revision history for this document Appendix A Ideality Factor Determination details the methodology used to determine the ideality factor of the CPU thermal diode Appendix B Pseudocode contains verbose pseudocode for all of the functions that comprise the ATMS 2 Functional Overview Figure shows a simplified block diagram of the ATMS The ATMS is possible by way of the thermal diode which resides on the processor die A temperature reading can be determined by measuring the change in the base emitter voltage Vpp of the diode when operated at different currents The resulting AV pg measurements can then be digitized and a
8. 0x20 to drop the External Temperature High Limit to 32 C a value below the current temperature reading This immediately triggers the INT 0 interrupt Instructions to test whether the ATMS is properly functioning l 2 10 11 12 13 14 15 16 Reset the board If there is not a valid environment type env c to initialize environment otherwise skip this step Type env Verbose 1 to turn verbose mode on Type ct d to disable the ATMS Verify the ADT7461 was disabled by analyzing the Configuration register which is printed out with the other ADT7461 registers on every ct command Type dev mpic init to initialize system interrupts Verify that the interrupts do not trigger and the fan speed is at 100 power Type ct x 0x10 to change the External Temperature High Limit register to 0x10 This causes the THERM2 flag to go low however no interrupts should be triggered Type ct e to enable the ATMS Verify that the ATMS was enabled and that a thermal threshold had been exceeded The fan should be at 100 power Type ct t 0x10 to change the External THERM Limit register to 0x10 This causes the THERM flag to go low and should trigger the INT 1 interrupt Verify that the fan is still at 100 and that DFS mode has been enabled by analyzing HID1 register output If verbose mode is enabled then the HID1 register value prints to the screen See above instruct
9. 1 to disable the ATMS 4 Reset the board Automatic Thermal Monitoring System on HPC Il Rev 0 10 Freescale Semiconductor DINK32 on HPC Il Board 5 Either apply direct heat or manually modify the ADT7461 registers until a thermal limit is surpassed Use the dt and ct commands to monitor the temperature and status register read from ADT7461 6 Verify that no action is taken even when a thermal limit is surpassed Instructions for using FANPWM environment variable to control fan speed 1 If there is not a valid environment type enc c to initialize environment otherwise skip this step 2 Type env Verbose 1 to turn verbose mode on 3 Type env FANPWM Oxnnnn where nnnn is a valid hex value Type env for help with FANPWM 4 Reset the board 5 Verify that on ADT7461 initialization the FANPWM environment variable was found the fan speed was set to FANPWM and no FAILURE messages appear by reading the verbose boot messages The fan speed should change and any large differences in fan speed should be audible Instructions for using TSHUTDOWN environment variable to shut down system NOTE USE WITH CAUTION A heat gun can melt solder or plastic parts and a processor with no heat sink quickly overheats 1 If there is not a valid environment type enc c to initialize environment otherwise skip this step 2 Type env Verbose 1 to turn verbose mode on 3 Type en
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11. OVER_ALARM in the FPGA which in turn produces the system interrupt INT 0 The bridge chip is responsible for then asserting an interrupt INT to the CPU These two interrupts provide the automatic capability of the ATMS enabling system interrupts and the ATMS to generate interrupts at key temperature thresholds and perform the action necessary to cool the system all without any user interaction The reads and writes to the thermal sensor are done through an PC bus or similar protocol that is SMBus Note that while two interrupt lines were available in this specific implementation it is possible to implement the ATMS with only one interrupt line In the one interrupt line case software would need to determine what caused the interrupt possibly by reading registers in the FPGA and after the cause was determined would then need to take the appropriate action Automatic Thermal Monitoring System on HPC Il Rev 0 2 Freescale Semiconductor Functional Philosophy NOTE Freescale makes no recommendations about the components used in this design Similar components from other vendors provide similar results The remainder of this application note details the setup used in Freescale s DSD Applications Lab IC Bus SCL FPGA _ Actel ProASICPLUS lt XINTO lt lt XINT1 THERM_ALARM lt lt OVER_ALARM lt Figure 1 Functional Block Diagram of ATMS 3 Functional Philosophy The three main operations cover
12. die junction temperature produced In this implementation a thermal monitor chip ADT7461 was used to read the diode temperature Standard A D can be used whereby exploiting the negative temperature coefficient of the diode can be used to measure Vpp However this method would require a non trivial amount of calibration due to a number of factors For example parasitic series resistance with the remote diode appears as a DC offset This introduces an error factor in the temperature reading seen as a number of C per ohm of parasitic resistance C Q The absolute value of Vgg which varies from device to device also appears as a constant temperature offset For these reasons specialized devices which can automatically compensate for many or all of these factors are typically used Otherwise these errors must be compensated for in software The main function of the Thermal Sensor within the ATMS is to interface with the thermal diode to produce a temperature reading The ADT7461 is a dual channel digital thermometer and under over temperature alarm It provides the extra benefit of two temperature limit flags namely THERM and ALERT THERM2 These flags are asserted when either a THERM limit or a Temperature High Low limit is exceeded both of these limits are user programmable The THERM flag translates to THERM_ALARM in the FPGA Actel ProASICPLUS which in turn asserts the system interrupt INT 1 to the bridge chip Tsi108 ALERT THERM2 translates to
13. C device address to thermal sensor Delay 1000 Delay for 1000 ms Set the Disable7461 global variable that controls whether thermal monitoring is enabled disabled Disable7461 0 if NULL TDISABLE environment variable temp TDISABLE if temp 1 Il temp 0 Disable7461 temp set global variable Disable7461 that will be used and modified by the rest of the ATMS Enable and initialize thermal sensor if Disable7461 0 write to thermal sensor on I2C bus to enable it else Put thermal sensor in Standby mode write to thermal sensor on I2C bus to disable it Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 19 Pseudocode Set local temp high limit based on processor type if 0 stremp CPUName MPC7447A temp 0x34 1 52degC else if 0 stremp CPUName MPC7448 temp 0x2C II 44degC else temp 0x55 power on default write temp to Loc Temp High Lim register in thermal sensor Set external temp high limit based on processor type if 0 stremp CPUName MPC7447A temp 0x34 1 52degC else if 0 stremp CPUName MPC7448 temp 0x2C II 44degC else temp 0x55 power on default write temp to External Temp High Lim register in thermal sensor write desired values to the rest of the thermal sensor registers Set hysteresis value based on processor type if 0 stremp CPUNam
14. Freescale Semiconductor Application Note Document Number AN2929 Rev 0 11 2005 Automatic Thermal Monitoring System on HPC Il by Brandon Ade Digital Systems Division Freescale Semiconductor Inc Austin TX 1 Introduction This application note applies to the MPC7447A and MPC7448 processors embedded on an HPC II platform It describes the implementation of an Automatic Thermal Monitoring System ATMS used to automatically control the processor core temperature When activated the ATMS cools the processor by two methods CPU fan control and CPU frequency throttling known as Dynamic Frequency Switching DFS The benefits of implementing an ATMS system are threefold it reduces power consumption reduces noise and provides a fail safe mechanism that powers off the system in the event of extreme operating temperatures The following section descriptions provide an overview of this document Section 2 Functional Overview provides a top level view of the ATMS and how the on board hardware interfaces and communicates Section 3 Functional Philosophy describes the major functional components of the ATMS Freescale Semiconductor Inc 2005 All rights reserved Contents 1 WOON ONS ot al hee Cc tee ee 1 2 Functional Overview 066c6ca cee ease renee 2 3 Functional Philosophy 2 000 3 3 1 Calibration on Startup 0 000000 4 3 2 System Interrupts 0 0 0 0 20
15. OxFFBFFFFF ExtTHERM and LocTHERM are globals defined in ct_exec whenever the user uses the ct command to change the THERM limits These globals are used to refresh the previous values when Automatic Thermal Monitoring System on HPC Il Rev 0 26 Freescale Semiconductor Pseudocode the limits are automatically changed by the ATMS Set the External THERM limit back to default if ExtTHERM 0 temp ExtTHERM else temp 0x55 write temp to External THERM Limit register in Thermal Sensor Set the Local THERM limit back to default if LocTHERM 0 temp LocTHERM else temp 0x55 write temp to Local THERM Limit register in Thermal Sensor print all register values in Thermal Sensor print_adt7461_registers return case e enable device Read current Configuration register value then AND out the standby bit temp value read from Thermal Sensor Configuration register temp temp amp OxBF clear Standby bit Take ADT7461 out of standby mode write temp to Thermal Sensor Configuration register delay to allow thermal sensor to come out of standby and refresh its registers Delay 2000 Check to see if interrupts have been enabled by reading the MSR register bit 16 MSR is a register that contains a bit that is 0 if interrupts are disabled and 1 if enabled msrCheck msr_read msrCheck msrCheck amp 0x00008000 gt gt 15 pul
16. Shutting down system power off system immediately THERM threshold already exceeded else if any of the THERM bits in statusRead are set Set the fan to 100 temp OxFF write temp to CPU fan control registers to set to 100 set DFS2 bit in HID1 SPR to throttle CPU frequency hid1 hid1_readQ hidtemp hid1 hid1_write hid1 0x00400000 Increase THERM thresholds Set the External THERM limit to shutdownTemp temp shutdownTemp write temp to Thermal Sensor External THERM Limit register Set the Local THERM limit to shutdownTemp temp shutdownTemp write temp to Thermal Sensor Local THERM Limit register switch interrupt INTO polarity to rising edge to be able to catch the next edge that will trigger an interrupt This edge signifies the temperature decreasing configure interrupt vector for the interrupt INTO to make its polarity rising edge Automatic Thermal Monitoring System on HPC Il Rev 0 Pseudocode Freescale Semiconductor 23 Pseudocode THERM2 threshold already exceeded else if any of the High Temperature Limit bits in statusRead are set Set the fan to 100 temp OxFF write temp to CPU fan control registers to set to 100 switch interrupt INTO polarity to rising edge to be able to catch the next edge that will trigger an interrupt This edge signifies the temperature decreasing configure interrupt vector for the inter
17. Specifications Rev 4 9 2005 Freescale Semiconductor Inc DINKRM DINK32 Reference Manual Rev 13 2 8 2005 Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 15 Revision History 7 Revision History Table 5 provides a revision history for this application note Table 5 Document Revision History Revision Date Substantive Change s 0 11 2005 Initial Release Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor Ideality Factor Determination Appendix A Ideality Factor Determination The ADT7461 is trimmed for an ideality factor n of 1 008 Likewise other thermal sensors will assume a certain nevalue If a transistor is being used whose n does not equal 1 008 or the assumed nValue then the Thermal Sensor must be calibrated by finding the correct np For the ADT7461 equation 1 is given to determine the error introduced at a temperature T Use this equation to determine the ideality factor by taking thermal measurements to determine T and AT Testing to determine the ideality factor of the MPC7448 thermal diode was done using a Marlow SE5010 Temperature Controller Four different processors were tested and an average was taken Note that the ideality factor found in testing will potentially differ from those found in hardware specifications This is only meant as a way of determining the ideality factor if one is not avail
18. able not known or if a more precise value is desired since the hardware specifications give a range and not a single value for nz Below are steps to determine the ideality factor of a single device as well as example results obtained in the DSD applications lab for the MPC7448 processor embedded on a HPC II development board NOTE During lab testing the diode always read above the expected value If it is critical that a system never reach above a specific temperature then setting the DC offset to 0 C by way of TOFFSET is recommended This will operate on the safe side since the ATMS errors on the positive side of temperature readings Steps for determining ideality factor 1 Take data points ranging from the minimum processor operating temperature to the maximum In this example the range was from 5 C 105 Compare these ideal values with actual values read from the diode using a Thermal Sensor See Table 6 for an example 2 Take the difference of the actual vs expected temperature readings and call this AT See Table 6 for an example 3 Equation 2 below can then be used to find the ideality factor AT is the difference and T is the expected golden value See Table 7 for an example of these results AT n 1 008 1 008 x 273 15 Kelvin T Eqn 1 Taken from reference 1 nz AT 273 15 Kelvin T x 1 008 1 008 Eqn 2 Derived from equation 1 4 Take averages of n and AT The DC offset wri
19. alization See section 6 6 development of interrupt handlers and when modifying the HID1 register Provided information about PLL bits contained within the HID1 register See section 9 1 1 7 development of interrupt handlers and when modifying the HID1 register Provided information about PLL bits contained within the HID1 register See section 9 1 1 8 all stages of the ATMS development 4 1 Environment The following instructions outline how to use the environment variables within the DINK32 kernel Instructions for using TOFFSET environment variable to set a DC offset on boot up 1 If there is not a valid environment type env c to initialize environment otherwise skip this step 2 Type env Verbose 1 to turn verbose mode on 3 Type env TOFFSET nnn where nnn is a valid whole number Type env for help with TOFFSET Reset the board 5 Verify that on ADT7461 initialization the TOFFSET environment variable was found and no FAILURE messages appear by reading the verbose boot messages 6 Type ct to print out the ADT7461 registers Verify that the correct offset value was written into the Offset register Instructions for using TDISABLE environment variable to disable the ATMS 1 If there is not a valid environment type env c to initialize environment otherwise skip this step 2 Type env Verbose 1 to turn verbose mode on 3 Type env TDISABLE
20. and THERM 2 triggers are Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 7 Functional Philosophy ISR_INT1 0 and ISR_INTOQ respectively Pseudocode for these functions can be found in Appendix B Pseudocode 3a 100 C 100C an se a a TSHUTDOWN System Shut Down 90 C THERM Limit 80 C INT1 Triggered 70 C T Q e 2 60 C o 50 C THERM2 Limit i INTO Triggered 40 C 99g I Fan 100 Fan 50 30 C FANPWM 1 DFS OFF I I THERM2 ma W Q 1 When the THERM2 limit is exceeded the THERM2 signal asserts low INTO is triggered and the fan is set to 100 2 If the temperature continues to increase and exceeds the THERM limit the THERM output asserts low INT1 is triggered and DFS mode is enabled The THERM limits are overwritten with the critical temperature limit 100 C or TSHUTDOWN if defined 3 a If the temperature continues to increase and exceeds the second THERM limit critical temperature limit the THERM output asserts low INT1 is called a second time and the system shuts down b If the temperature does not reach the critical temperature limit then no action is taken 4 As the system cools down and the temperature falls below the THERM2 limit minus hysteresis in this case it is set to zero the THERM2 signal resets goes high INTO is called the fan is set to FANPWM if defined else 50 and DFS mode is disabled The THERM l
21. ature was read from the CPU thermal diode Table 2 Number of Interrupt Calls Versus Hysteresis Values Hysteresis Effect on MPC7447A with External and Local Temperature Thresholds set to 0x34 52 C DC Offset 0 C Hysteresis Value Length of Test min INT Calls Minutes Call Calls Min 0x00 4 236 0 017 59 000 0x01 14 18 0 778 1 286 0x02 20 11 1 818 0 550 0x03 100 47 2 128 0 470 0x04 1020 211 4 834 0 207 0x05 120 1 120 000 0 008 Hysteresis Effect on MPC7448 with External and Local Temperature Thresholds set to 0x2C 44 C DC Offset 4 C Hysteresis Value Length of Test min INT Calls Minutes Call Calls Min 0x00 1 59 0 017 59 000 0x01 17 16 1 063 0 941 0x02 28 15 1 867 0 536 0x03 53 19 2 789 0 358 0x04 92 20 4 600 0 217 0x05 83 8 10 375 0 096 Four environment variables directly affect the ATMS setup TOFFSET FANPWM TDISABLE and TSHUTDOWN TOFFSET allows for individual systems to be calibrated after a specific ideality factor is found for that system This environment variable sets the DC offset of the Thermal Sensor which is then automatically applied on every temperature read If this variable is not set then a default DC offset is assigned depending on processor type If the ideality factor n of a device is defined in the hardware specification then use that value to determine the default DC offset Use Eq
22. e MPC7447A temp 0x04 else if 0 stremp CPUName MPC7448 temp 0x05 else temp Ox0A write temp to hysteresis register in thermal sensor Set up ADT7461 DC offset based on TOFFSET environment variable The 25degC resolution of the offsets are ignored for simplicity and implementation sake if NULL TOFFSET envalue TOFFSET converted from string to numeric value write envalue to Offset register in thermal sensor else TOFFSET does not exist assign DC offset to default value if 0 stremp CPUName MPC7447A for this implementation the MPC7447A was not calibrated therefore DC offset is just set to 0x00 envalue 0x00 write envalue to Offset register Automatic Thermal Monitoring System on HPC Il Rev 0 20 Freescale Semiconductor Pseudocode else if 0 stremp CPUName MPC7448 write to Offset High Byte register envalue OxFC II AdegC write envalue to Offset register return adt7461_init 7 HR 2g 2 he Ae 2 hee EEEE EENE EREE 2A he EEE 2A he 2 he 2 he 2 26 2 2 oe hehe 2 22k fan_init This function checks for the FANPWM environment variable and if found writes to the TPWML and TPWMH registers that control the CPU fan speed This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 9 22 05 Ret
23. e no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document Freescale Semiconductor reserves the right to make changes without further notice to any products herein Freescale Semiconductor makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation consequential or incidental damages Typical parameters which may be provided in Freescale Semiconductor data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including Typicals must be validated for each customer application by customer technical experts Freescale Semiconductor does not convey any license under its patent rights nor the rights of others Freescale Semiconductor products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur Should Buyer purchase or use
24. ed in this application note are as follows 1 Calibration of the ATMS using environment variables 2 Command line options of the ATMS 3 System interrupts Figure 2 shows the structure of the code that controls the ATMS broken into the three main components of the system The italicized functions are those that pertain specifically to the ATMS The file main c contains the main loop for the kernel In this implementation the kernel is Freescale s Dynamic Interactive Nano Kernel for 32 bit processors DINK32 which is publicly available under license from Freescale During boot up DINK32 initializes the environment which makes calls to the ATMS specific functions adt7461_init and fan_init described in detail in Section 3 1 Calibration on Startup The file gme c contains a number of device operations and command line processing for DINK32 and specifically to the ATMS contains the code to handle the command line options available to interface and calibrate the ATMS These functions are described more thoroughly in Section 4 2 Command Line Interface The file mpic1 c is the interrupt handler for DINK32 It is responsible for initializing the ATMS when system interrupts are enabled as well as for calling the proper interrupt handler for the THERM and ALERT THERM72 flags when they are asserted The ATMS specific functions ISR_INT0Q ISR_INT10 Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 3 Func
25. elect the ADT7461 as the desired device to access on the IC bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms display current register settings can be used to verify changes PRINT n tADT7461 Register Settings PRINT n t e PRINT n tRegister tName tValue PRINT n t t t read each register in the Thermal Sensor and print out name and value Automatic Thermal Monitoring System on HPC Il Rev 0 Pseudocode Freescale Semiconductor 31 Pseudocode TEX II gme_I2C_acc unsigned long 0x02 amp temp B_ACCESS GME_R PRINT n t 0x02 tStatus t t t tOx 2 2X n temp return print_adt7461_registers ic1 mpict c 78 Pa AN AOK 2 he 2 EAE abe he 2A fe INE EDE IE 2 2A 2 2 he 2A Ae 2 hee ABE 2 2A he 2A Ae 2 he 2 Ae 2 2A he IAE he 2 he ole Ae afede oe hehe Ea adt7461_interrupt_init This routine sets up the TICK register settings and fan speed for the ATMS This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 09 07 05 Return void AVA ERAR HEF 2 ee A 2 EEEE EK AE HG Ae 2 62 EA FAC FA IC 2 A 2 i 6 2 C2 IG 2 EREEREER void adt7461_interrup
26. hermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 25 Pseudocode switch b write default values to all valid registers see ADT7461 datasheet pg 14 for power on defaults case a write power on default values to all the registers in Thermal Sensor use function to print out registers in the Thermal Sensor print_adt7461_registers return case d disable device Disable interrupt vectors so they are no longer triggered Disable7461 1 set global disable variable so that all other functions know that the ATMS is disabled mpicIntDisable 0 disable INTO interrupt vector mpicIntDisable 1 disable INT 1 interrupt vector Read current Configuration register value then OR the standby bit temp value read from Thermal Sensor Configuration register Put ADT7461 in standby mode temp temp 0x40 set standby bit write temp to Thermal Sensor Configuration register Set the fan to FANPWM if environment variable is defined otherwise set to 100 fan_init Since no longer monitoring if DFS is enabled then set THERM thresholds to previous values and disable DFS mode Read the HID1 register to obtain status of the DFS2 bit hid1 hid1_readQ hid1 amp 0x00400000 if hid1 Reset DFS2 bit in HID1 SPR to set CPU core freq to max hid1 hid1_readQ hidtemp hid1 clear DFS bit in HID1 and write back to HID1 hid1_write hidl amp
27. imits are also reset to their previous values default 0x55 Figure 3 Operation of the THERM and THERM2 Interrupts Automatic Thermal Monitoring System on HPC Il Rev 0 8 Freescale Semiconductor Functional Philosophy ISR_INTO Called ISR_INT1 Called Yes 1 Figure 4 Interrupt Handler Flowchart Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 9 DINK32 on HPC II Board 4 DINK32 on HPC Il Board When operating under the DINK32 kernel on a HPC II development board the following sections can be used for debug and test purposes At the DINK32 command prompt typing env ct or dt displays a help screen for the environment variables command the configure temperature command or the display temperature command respectively Table 3 outlines the references that were used during development of the ATMS These are specific to the MPC744X line of processors and the HPC II development board but will provide a greater understanding of how the ATMS was developed Table 3 References Used in ATMS Development Reference Used During 1 all stages of the ATMS development 4 development of the interrupt handlers and when modifying the HID1 register Specifically see section 2 2 5 2 5 development of the interrupt handlers Specifically for information on TICK registers that controlled fan speed power off ability and interrupt initi
28. ing of the dt and ct commands are dt_exec and ct_exec respectively The pseudocode for these functions are in Appendix B Pseudocode Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 11 DINK32 on HPC II Board Table 4 Configure Temperature Command Description Syntax ct ade o therm t therm s hyst x xlim 1 loclim c rate r alert g config Description This command allows the ADT7461 temperature monitor to be fully configured from the command line It can also disable enable the device which in turn disables enables the entire thermal monitoring system Typing only ct displays the current register settings which also display after every ct command NOTE The flags a d and e can only be used separately from all other flags options and must be the first flags in the command line That is ct a CORRECT ct d CORRECT ct e CORRECT ct a d or any other flag WRONG Options Description a Auto configure Thermal Sensor to power on default settings d Disable the Thermal Sensor and put in standby mode e Enable the Thermal Sensor o therm Set the Local THERM Limit ttherm Set the External THERM Limit s hyst Set the THERM Hysteresis value x xlim Set the External Temperature High Limit I loclim Set the Local Temperature High Limit c rate Set the Conversion Rate of
29. ions for how to enable verbose mode Verify that the External and Local THERM thresholds of the ADT7461 have both been changed to TSHUTDOWN if defined else 0x64 100 C if TSHUTDOWN is not defined Type ct x 0x60 to change the External Temperature High Limit register to 0x60 If the current temperature is above 0x60 use whatever value is greater than the current temperature reading Verify that the INT O interrupt was triggered The fan should be set to FANPWM if defined otherwise it should be set to 50 power DFS mode should be disabled THERM limits should be set back to 0x55 85 C Type ct d to disable the ATMS Verify that the ATMS was disabled by analyzing the Configuration register in the ADT7461 and that the fan is at 100 power Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor Conclusion Instructions to verify that the power off fail safe is working 5 NOTE USE WITH CAUTION A heat gun can melt solder or plastic parts and a processor with no heat sink quickly overheats Reset the board Type dev mpic init to enable system interrupts Use a heat gun or some other means to physically heat the processor The heat sink can also be removed however the processor will reach over 100 C very quickly Ensure that the system is set up properly and use caution The dt command can be used to monitor the real time temperature Verify that the board
30. l out bit if msrCheck check_limits if interrupts are enabled then need to check what the current temperature readings are and set the appropriate thresholds Enable interrupt vectors so they are triggered when a threshold is passed Disable7461 0 set global disable variable so that all other functions know that the ATMS is enabled mpicIntEnable 0 enable INTO interrupt vector mpicIntEnable 1 enable INT 1 interrupt vector print all the registers in the Thermal Sensor Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 27 Pseudocode print_adt7461_registers return Process all other commands if flag is other than a d e then try to find a valid hex value that will be written to register if token strtok NULL NULL amp amp b 7 if arg_getvalue amp token amp test 16 SUCCESS if flag and value are valid place both into their appropriate arrays optstr j b datastr j test JH continue searching arg string until no more valid tokens are found while token strtok NULL NULL make sure that argument is a valid flag if b arg_getopts amp token toxlcegaders 0 amp da 0 if flag is other than a d e then try to find a valid hex value that will be written to register if token strtok NULL NULL amp amp b if
31. nge 0 0 127 degC 1 Extended Range 1 0 Reserved Instructions for starting the ATMS with visual output from DINK32 1 After the system has been rebooted the ATMS is by default enabled 2 If there is not a valid environment type env c to initialize environment otherwise skip this step 3 Type env Verbose 1 to turn verbose mode on 4 Type dev mpic init to initialize system interrupts 5 The ATMS is now fully functioning with visual feedback Instructions for starting the ATMS without visual output from DINK32 1 After the system has been rebooted the ATMS is by default enabled 2 Type dev mpic init to initialize system interrupts 3 The ATMS is now fully functioning Instructions for using the Display Temperature dt command 1 The dt command can be used at any time by simply typing dt To manually trigger an interrupt 1 Ensure that the ATMS is enabled and system interrupts are enabled 2 Type dt to display the current temperature reading Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 13 DINK32 on HPC II Board 3 Use the ct command to modify one of the Temperature Limit or THERM Limit registers to a value that is less than the current temperature displayed when using dt This causes the corresponding interrupt to trigger Example dt displays an external temperature of 48 00 C 0x30 type ct x
32. ode else if environment variable not found then set fan to 50 temp OxAA write temp to CPU fan control registers Read the HID1 register to obtain status of the DFS2 bit hid1 hid1_readQ hid1 amp 0x00400000 parse out DFS bit if hid1 If DFS is enabled disable it Reset DFS2 bit in HID1 SPR to set CPU core freq to max hid1 hid1_readQ hidtemp hid1 hid1_write hid1 amp O0xFFBFFFFF clear DFS2 bit ExtTHERM and LocTHERM are globals defined in ct_exec whenever the user uses the ct command to change the THERM limits These globals are used to refresh the previous values when the limits are automatically changed by the ATMS Set the External THERM limit back to previous values if ExtTHERM 0 temp ExtTHERM else temp 0x55 write temp to External THERM Limit register in Thermal Sensor Set the Local THERM limit back to previous values if LocTHERM 0 temp LocTHERM else temp 0x55 write temp to Local THERM Limit register in Thermal Sensor In order to catch the next rising falling edge the polarity of the interrupt vector must be swapped It is simply the inverse of its current state polarity srcVal amp MPIC_MPIC_IVPRO_P gt gt 24 parse polarity bit polarity polarity 0 1 0 swap polarity bit write to register that controls the polarity interrupt vector 0 return ISR_INTOQ Automatic Thermal Monit
33. old but will not be disabled when the temperature drops below this theshold Instead DFS mode is kept on until the temperature drops passed the THERM2 trigger limit Also during the first INT 1 interrupt call see point 2 in Figure 3 the THERM limits inside of the Thermal Sensor are changed to the environment variable TSHUTDOWN if this variable is defined If TSHUTDOWN is not defined then the THERM limits are changed to a default of 0x64 100 C This ensures that if the temperature continues to increase to the critical temperature limit the INT 1 interrupt will still be triggered on a falling edge and a system shut down can occur providing the fail safe functionality of the ATMS Note that this system shut down temperature can be other than 100 C by simply defining the TSHUTDOWN environment variable Note that in the HPC II design example temperatures and THERM limits lower than 0 C were not considered See the ADT7461 data sheet for a more detailed description of how the temperature limit interrupts work and how they could be used in other implementations The interrupt vectors 0 and 1 are initialized in the function adt7461_interrupt_init when the system interrupts are enabled If the ATMS is disabled by way of the ct d command or from the TDISABLE environment variable then the ATMS interrupts will still be initialized but will not be active After initialization the interrupt service routines responsible for handling the THERM
34. oring System on HPC Il Rev 0 34 Freescale Semiconductor POE A 2 2 he Ae AEE 62 2A he A Ae E E B ENEE 2 2 he AEE 2 hee AE 2 2 he 2A 2K oie ISR_INT1 THERM interrupt handler This interrupt handler is part of the thermal monitoring system that attempts to cool the processor using a combination of CPU throttling and CPU fan control This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 08 18 05 Return void AVENE R Ik HF e 6 2 2 HG A 2 HG C2 ake abeak C2 HR 2 C2 FR A IE 2H 2 CE 2 void ISR_INT1 ULONG vector int hid1 HID1 read value int hidtemp temp used to write to HID1 ULONG da device address of thermal sensor ULONG locTemp extTemp ADT7461 loc and ext thermal values ULONG shutdownTemp critical overheat temperature ULONG temp shutdownTemp 0 locTemp 0 extTemp 0 hid1 0 hidtemp 0 da 0 temp 0 Select the ADT7461 as the desired device to access on the 1 C bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms locTemp value read from Thermal Sensor Local Temp register extTemp value read from Thermal Sensor External Temp register set critical temperature limit if TSHUTDOWN env variable is defined sh
35. powers off at either TSHUTDOWN if it is defined or 100 C if TSHUTDOWN is not defined Conclusion The presence of a substrate thermal diode simplifies the implementation of the ATMS If a thermal diode is not present on the processor die it is possible to buy an external transistor or diode to place near the processor This diode can then be interfaced with in similar means to the substrate diode to obtain a temperature reading Freescale s latest PowerPC processors avoid this extra effort and hardware by providing an on chip thermal diode that is ready to easily interface with By providing a third party thermal sensor and software to control the ATMS it becomes simple to implement a full thermal solution into a system 6 References Analog Devices ADT7461 1 C Temperature Monitor with Series Resistance Cancellation Specification Rev 0 2003 Actel ProASICPLUS Flash Family FPGAs Datasheet Rev 3 5 04 2004 Tundra Tsil0S Host Bridge for PowerPC User Manual http www tundra com Freescale Semiconductor Inc MPC7450UM MPC7450 RISC Microprocessor Family Reference Manual Rev 5 1 2005 Freescale Semiconductor Inc HPCIIUG HPC IJ A High Performance Low Profile Server System Rev 1 1 7 2005 Freescale Semiconductor Inc MPC7448EC MPC7448 RISC Microprocessor Hardware Specifications Rev 0 9 2005 Freescale Semiconductor Inc MPC7447AEC MPC7447A RISC Microprocessor Hardware
36. r address of interrupt vector 0 int polarity polarity of interrupt vector 0 ULONG da device address of thermal sensor ULONG temp hid1 0 hidtemp 0 srcVal 0 srcAddr 0 polarity 0 da 0 temp 0 Select the ADT7461 as the desired device to access on the 1 C bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms Find current polarity of vector 0 to determine rising or falling edge trigger This code is DINK32 specific For other systems just determine the current polarity of the interrupt srcAddr mpicVecTable vector srcAddr srcVal sysMpicRegRead srcAddr read vector register polarity srcVal amp MPIC_MPIC_IVPRO_P gt gt 24 parse polarity bit if falling edge is detected if 0 polarity Turn the fan full on to try and cool processor Set the fan to 100 temp OxFF write temp to CPU fan control registers to set to 100 else else rising edge set the fan to FANPWM if it is defined otherwise set to default 50 if NULL FANPWM convert FANPWM to ULONG and massage in order to write to PWM registers temp FANPWM with necessary conversions write temp to registers that control CPU fan speed Automatic Thermal Monitoring System on HPC II Rev 0 Pseudocode Freescale Semiconductor 33 Pseudoc
37. r given in the hardware specification be used to determine the default DC offset Ext Temp 12 0x00 0x00 0 25 decimal precision is not used in this Offset Low implementation Byte Ext Temp High 13 0x00 0x00 Unchanged Limit Low Byte Ext Temp Low 14 0x00 0x00 Unchanged Limit Low Byte External 19 0x55 0x55 85 C Unchanged THERM Limit Local THERM 20 0x55 0x55 85 C Unchanged Limit THERM 21 Ox0A if CPU MPC7447A These values were derived from DSD applications lab Hysteresis 0x04 4 testing Table 2 gives the results of this testing The if CPU MPC7448 desired value is one that reduces power consumption 0x05 5 overall noise and still properly controls the temperature Consecutive 22 0x01 0x00 Since the critical overheat temperature is set to 100 C ALERT by default it is desirable to have this interrupt trigger immediately since it is unlikely to occur twice before the CPU reaches its maximum temperature rating 1 from the CPU thermal diode Local temperature limits refer to the internal temperature monitor of the ADT7461 external limits refer to temperatures read Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor Functional Philosophy Note the ATMS monitors both local and external limits Therefore if the ambient temperature around the ADT7461 reaches any of the temperature thresholds the corresponding interrupts will be triggered as if the temper
38. rupt INTO to make its polarity rising edge no temperature thresholds have been exceeded else set the fan to FANPWM if it is defined otherwise set to 50 if NULL FANPWM convert FANPWM to ULONG and massage in order to write to PWM registers pwmvalue FANPWM with necessary conversions write pwmvalue to registers that control CPU fan speed else if environment variable not found then set fan to 50 pwmvalue 0OxAA write pwmvalue to registers that control CPU fan speed switch INTO polarity to falling edge in case it had been changed elsewhere but a disable of the ATMS prevented the interrupt from switching the polarity back when threshold was crossed configure interrupt vector for the interrupt INTO to make its polarity falling edge return check_limits Automatic Thermal Monitoring System on HPC Il Rev 0 24 Freescale Semiconductor Pseudocode TOE AEE A AEN Ae EIN RE IEE NE AEN he 2 EDE IE SN I 2 2 he EME 2 INe INE ABE 2 2A he 2A Ae 2 AEDE RE SHEE AE IRE fe 2 he 2 Ae 2 Ae oe hehe 2A 2k ct_exec Auxilliary function for the ct command called by par_gme This function handles all of the possible ct commands and performs the proper function depending on user s command line arguments It also handles enabling and disabling the ATMS and ensuring that the proper thermal thresholds are set up This app note contains pseudocode instead of the full
39. t_init ULONG tisrinit value to write to TISR register The TISR register contains the bits that control the settings of the interrupt vectors and how they are handled tisrinit 0 If Disable7461 global is not set then check for limits and initialize thermal system Disable7461 O enabled 1 disabled if Disable7461 check_limits if ATMS is enabled then check temperature thresholds Set up TISR register at address 0x40 in the TICK register set to allow for THERM flag to trigger INT 1 and ALERT THERM2 flag to trigger INT O tisrinit 0x24 write tisrinit to TISR interrupt settings register return adt7461_interrupt_init Automatic Thermal Monitoring System on HPC Il Rev 0 32 Freescale Semiconductor POR CR ICE ICICI IRCA IC I A aR aa ak ok ak ISR_INTO ALERT THERM2 interrupt handler This interrupt handler is part of the ATMS that attempts to cool the processor using a combination of CPU throttling and CPU fan control This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 08 18 05 Return void AVAL E a a aea a aea ak aea ake CS SG A SCS SS A ak OR kak a void ISR_INTO ULONG vector int hid1 HID1 read value int hidtemp temp used to write to HID1 ULONG srcVal used when reading polarity of INT 0 ULONG srcAdd
40. the Thermal Sensor r alert Set the Consecutive ALERT count of the Thermal Sensor g config Modify Configuration Register bits in the Thermal Sensor therm THERM limit value given in hex from 0x00 0xFF Default 0x55 85degC hyst THERM Hysteresis value given in hex from 0x00 OxFF Default Ox0A 10degC xlim External Temperature High Limit value given in hex from 0x00 OxFF Default 0x55 85degC loclim Local Temperature High Limit value given in hex from 0x00 OxFF Default 0x55 85degC Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor DINK32 on HPC II Board Table 4 Configure Temperature Command Description continued Options Description rate Conversion rate value given in hex Default 0x08 16c s c s stands for conversions per second 0x00 gt 0 0625 c s 0x06 gt 4 0c s 0x01 gt 0 125 c s 0x07 gt 8 0 c s 0x02 gt 0 25 c s 0x08 gt 16 0 c s 0x03 gt 0 5 c s 0x09 gt 32 0 c s 0x04 gt 1 0 c s OxOA gt 64 0 c s 0x05 gt 2 0 c s alert Determines how many out of limit measurements must occur before an ALERT is generated 0x00 gt 1 0x03 gt 3 0x01 gt 2 0x07 gt 4 config 8 bit hex value from 0x00 0xFF Default 0x00 See ADT7461 data sheet for an in depth description of these bits Bit Name Function 7 MASK1 O ALERT Enabled 1 ALERT Masked 6 RUN STOP 0 Run 1 Standby 5 ALERT THERM2 O ALERT 1 THERM2 4 3 Reserved 2 Temp Ra
41. tional Philosophy and adt7461_interrupt_init provide the automatic interrupt functionality and are described in more detail in Section 3 2 System Interrupts Calibration with Command Line Options Environment Variables Interrupts Figure 2 Function Hierarchy of ATMS Software 3 1 Calibration on Startup On system boot up the ATMS is calibrated by writing to the Thermal Sensor registers The function adt7461_init handles making the initial writes on the PC bus to calibrate the Thermal Sensor Table 1 gives the register values for this specific implementation of the ATMS Again these values are user and system specific and with different preferences or devices will change accordingly See ADT7461 1 C Temperature Monitor with Series Resistance Cancellation Specification for further details about these registers Table 1 Initial Register Writes to Thermal Sensor ADT7461 on Boot Up Register Write Address Power On Written Value at Boot Up Reaso Name Hex Default Hex Configuration 09 0x00 if Disable7461 0 Disable7461 is a global variable that is assigned based OxAO on the current ATMS status It is 0 if the ATMS is if Disable7461 1 enabled and 1 if the ATMS is disabled OxEO Conversion OA 0x08 0x07 8 c s At 8 Conversions Second the ADT7461 does its own Rate internal averaging At gt 8c s no averaging is done Local Temp 0B 0x55 if CPU MPC7447A Same as CPU core tempera
42. tten to the Thermal Sensor will be AT It could be beneficial to take averages across certain temperature ranges depending on the temperature range being optimized for See Table 8 for examples of this averaging Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 17 Ideality Factor Determination Table 6 Raw Data Example of Expected Temperature vs Actual Temperature Thermo Couple Reading Diode Reading using Marlow Set C T C Thermal Sensor C AT C actual T T actual 5 5 00 10 50 5 50 15 15 00 19 75 4 75 25 25 00 29 50 4 50 35 35 00 39 00 4 00 45 45 00 48 75 3 75 55 55 00 58 50 3 50 65 65 00 68 25 3 25 75 75 00 78 25 3 25 85 85 00 88 00 3 00 95 95 00 97 75 2 75 105 105 00 107 50 2 50 Table 7 Ideality Factor Based on T and AT using Eq 2 T C AT C Ideality Factor n 5 00 5 50 1 0279 15 00 4 75 1 0246 25 00 4 50 1 0232 35 00 4 00 1 0211 45 00 3 75 1 0199 55 00 3 50 1 0188 65 00 3 25 1 0177 75 00 3 25 1 0174 85 00 3 00 1 0164 95 00 2 75 1 0155 105 00 2 50 1 0147 Table 8 Example of Ideality Factor and DC Offset Averages for MPC7448 Overall 5 25 C range 35 65 C range 75 105 C range AT avg 3 70 4 92 3 63 2 88 npavg 1 0197 1 0253 1 0194 1 0160 Automatic Thermal Monitoring System on HPC Il Rev 0 18 Freescale Semiconductor
43. ture limit High Limit 0x34 52 C if CPU MPC7448 0x2C 44 C Automatic Thermal Monitoring System on HPC II Rev 0 4 Freescale Semiconductor Functional Philosophy Table 1 Initial Register Writes to Thermal Sensor ADT7461 on Boot Up continued Register Write Address Power On Written Value at Boot Up Basson Name Hex Default Hex Local Temp oc 0x00 0x00 0 C Unchanged Low Limit Ext Temp High oD 0x55 if CPU MPC7447A During applications lab testing with a MPC7447A Limit High Byte 0x34 52 C 52 C 0x34 was the peak temperature the CPU if CPU MPC7448 reached when powered on without strenuous code Ox2C 44 C execution For the MPC7448 this value was 44 C 0x2C Note These thermal limits are system and processor specific Ext Temp Low 0E 0x00 0x00 Unchanged Limit High Byte Ext Temp 11 0x00 if CPU MPC7447A TOFFSET is an environment variable that is checked Offset High AND TOFFSET NULL on bootup If TOFFSET is defined then its value is used Byte 0x00 as the DC offset value applied to the Thermal Sensor if CPU MPC7448 AND If TOFFSET is not defined then a default value is TOFFSET NULL written based on CPU type The MPC7447A was not OxFC 4 C tested for this in the DSD applications lab so this if TOFFSET NULL specific implementation uses the ADT7461 default of TOFFSET zero However it is recommended that the worst case ideality facto
44. uation in Appendix A Ideality Factor Determination to directly find this DC offset given nz However if an n value is not known or a more specific ny value is required Appendix A outlines a methodology to determine the ng and DC offset for a specific device Testing done on a MPC7448 processor in the DSD applications lab found an overall average temperature reading of 4 32 above expected corresponding to a value of 4 C as the default DC offset for this implementation This value of 4 C is applied as a default when TOFFSET is not defined for a MPC7448 Automatic Thermal Monitoring System on HPC Il Rev 0 6 Freescale Semiconductor Functional Philosophy FANPWM if defined is used as the fan speed when the ATMS is enabled and no thermal thresholds have been exceeded If FANPWM is not defined then a default value of 50 is used for the fan speed when the ATMS is idle and no thresholds have been reached FANPWM also provides the user the ability to control the CPU fan speed regardless of the ATMS status Whether the ATMS is enabled or disabled FANPWM can be defined to set the fan speed on boot up Note that when the ATMS is enabled the fan speed is set to 100 when the first thermal threshold is reached THERM2 TDISABLE disables enables the ATMS If this environment variable is set to 1 then the ATMS is disabled When disabled the Thermal Sensor is put in standby mode and no longer makes temperature conversions S
45. urn void HAY APD Po A CH A CC A CR void fan_init ULONG pwmvalue value for CPU fan register in DINK32 the CPU fan is controlled by a PWM register Writing to this register different values will change the fan speed if NULL FANPWM convert FANPWM to ULONG and massage in order to write to PWM registers pwmvalue FANPWM with necessary conversions write pwmvalue to registers that control CPU fan speed else if environment variable not found then set fan to 100 pwmvalue OxFF write pwmvalue to registers that control CPU fan speed return fan_init Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 21 Pseudocode gme c 78 PR A 2 2 he AAEE 6 2 2A he A he 2A ED aE 2 2A 2 2 he EME 2 26 2 BEGE 2A he A Ae 2 aee aE Shea IRERE he 2 he 2 Ae afe 2 oe hehe 2 22k check_limits This function checks to see if any thresholds have already been exceeded during an enable of the thermal system Without this function if a threshold was already exceeded then the thermal system would not recognize subsequent rising falling edges properly This function is needed to set the correct thermal system settings no matter what temperature range the thermal system is enabled in This app note contains pseudocode instead of the full version DINK32 with the full code is publicly available under license from FSL x Author Brandon Ade
46. utdownTemp TSHUTDOWN else shutdownTemp 100degC Critical system threshold exceeded Shut down system if temperature gt shutdownTemp if locTemp gt shutdownTemp II extTemp gt shutdownTemp PRINT n tCritical overheat temperature detected PRINT n tShutting down system power off system immediately else THERM threshold exceeded enable DFS Automatic Thermal Monitoring System on HPC Il Rev 0 Pseudocode Freescale Semiconductor 35 Pseudocode set DFS2 bit in HID1 SPR to throttle CPU hid1 hid1_readQ hidtemp hid1 hid1_write hid1 0x00400000 set DFS2 bit Increase THERM thresholds in Thermal Sensor Set the External THERM limit to shutdownTemp temp shutdownTemp critical temperature limit write temp to External THERM Limit register in Thermal Sensor Set the Local THERM limit to shutdownTemp temp shutdownTemp critical temperature limit write temp to Local THERM Limit register in Thermal Sensor return ISR_INT1 Automatic Thermal Monitoring System on HPC Il Rev 0 36 Freescale Semiconductor Pseudocode THIS PAGE INTENTIONALLY LEFT BLANK Automatic Thermal Monitoring System on HPC Il Rev 0 Freescale Semiconductor 37 Pseudocode THIS PAGE INTENTIONALLY LEFT BLANK Automatic Thermal Monitoring System on HPC Il Rev 0 38 Freescale Semiconductor Pseudocode THIS PAGE INTENTIONALLY LEFT BLANK
47. v TSHUTDOWNE nnn where nnn is a valid decimal value between 0 and 255 Type env for help with TSHUTDOWN 4 Reset the board 5 Type dev mpic init to initialize system interrupts 6 Use a heat gun or some other means to physically heat the processor The heat sink can also be removed however the processor will reach over 100 C very quickly Ensure that the system is set up properly and use caution The dt command can be used to monitor the real time temperature 7 Verify that the board powers off when TSHUTDOWN is reached 4 2 Command Line Interface The DINK32 implementation provides two command line options that allow the user to interface with the ATMS These commands are display temperature dt and configure temperature ct The dt command simply reads the local and external temperature values from the thermal sensor and prints these readings in Celsius and hexadecimal The ct command is the heart of the ATMS and provides robust user capabilities This command is used for the majority of operations when working with the ATMS Table 4 gives a description of the syntax and flags used with the ct command Note If the a d or e flags are used they should be used separately from all other flags Otherwise any number of flags in any order can be used with the ct command Keep in mind that the dt and ct commands are ADT7461 and DINK32 specific The functions that handle the process
48. version DINK32 with the full code is publicly available under license from FSL Author Brandon Ade Date 09 08 05 Return void NJ APD ie a a HR A CC A CR CA CCR CA AC AC AC void ct_exec char args char b holds read bytes from command line arguments ULONG da test device address and valid argument test char token tokens for strtokQ char optstr 20 array containing valid flags ULONG datastr 20 array containing valid hex values from command line int i j LCVs ULONG temp used as temp to write static values to Thermal Sensor int hid1 HID register value int hidtemp temp when modifying HID1 register ULONG msrCheck holds bits read from MSR register msrCheck 0 hidtemp 0 hid1 0 temp 0 i 0 j 0 da 0 test 0 Select the ADT7461 as the desired device to access on the 2C bus by setting the correct device address da thermal sensor device address gme_SetDevAddr da set PC device address to thermal sensor Delay 1000 Delay for 1000 ms tokenize argument string in order to process each flag option one at a time and to check for invalid entries if token strtok args NULL make sure that argument is a valid flag if b arg_getopts amp token toxlcgaders 0 amp da 0 since a d e are to be used separately check for them first and perform direct operations and return Automatic T
49. ystem interrupts can also be enabled as these will be ignored by the ATMS when it is disabled When the ATMS is disabled the CPU fan speed reverts back to the FANPWM environment variable If this environment variable is not defined the fan is set to 100 TSHUTDOWN sets the critical temperature shutdown limit of the ATMS on boot up This environment variable is part of the fail safe feature of the ATMS It guarantees that at a predefined temperature the system will shut down If TSHUTDOWN is not defined then a default value of 100 C is used as the critical temperature limit The function adt7461_init calibrates the ATMS and the function fan_init initializes the fan speed settings using FANPWM Appendix B Pseudocode contains commented pseudocode for both of these functions 3 2 System Interrupts Interrupts provide the automatic capability of the ATMS As mentioned in Section 2 Functional Overview threshold flags sent from the Thermal Sensor are translated to system interrupts namely INT O and INT 1 The operation of these interrupts and the thermal thresholds that trigger them are shown in Figure 3 Following Figure 3 is a description of what occurs at each edge trigger Figure 4 is a flowchart showing how the interrupts operate The parenthesized numbers in the flowchart correspond to the numbered trigger points in Figure 3 During the design process it was decided that DFS mode will be enabled at the first THERM thresh

Automatic Thermal Monitoring System on HPC II

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