Themis USPIIi-1v, Hardware Manual

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Themis Computer
6-5
6. FPGA, Watchdog, Voltage and Temperature Sensors
6.2 Temperature Sensor
The temperature sensor is implemented using registers in the FPGA and the Dallas Semiconductor DS1620
Digital Thermometer and Thermostat. The Dallas DS1620 provides 9-bit temperature readings which indicate
the temperature of the device. The Dallas DS1620 device is located close to the UltraSPARC-II
i to provide an
accurate reading of the temperature around the processor.
Two user defined temperatures are stored in the Dallas DS1620’s NVRAM: temp-warning and temp-critical .
These variables may be configured by through OBP extension variables (refer to the “USPIIi-1v Software
Manual”). The settings of temp-critical and temp-warning are stored in the 8-bit TL and 8-bit TH registers of
the DS1620.
Warning —
!
Do not re-configure the temperature warning settings on the USPII i -1v. Altering these
variables may seriously damage the product. If there are problems with the temperature sensor on the
board, contact Themis Customer Service immediately.
Temperature sensor reaching warning temperature will turn the front ALARM LED to amber. At critical
temperature, the LED will turn RED and the HI TEMP signal will be asserted on VME P2. See Appendix
A.2.2, "Baseboard VME P2," and Appendix A.2.9, "LEDs."