GR740-UM-DS, Nov 2017, Version 1.7
353
www.cobham.com/gaisler
GR740
29
Temperature sensor controller
29.1
Overview
This peripheral provides an interface to the on-chip temperature sensor. It allows software to control
the temperature sensor, saves maximum and minimum temperature values and allows generation of
alarms.
Note: The temperature sensor can only be used in devices with revision 1 of the package. All devices
with silicon revision 1 also has package revision 1. See section 42 for further information.
29.2
Operation
The temperature sensor provides digital measurement of junction temperature. The sensor is con-
trolled by software via the register interface described in this documentation.
The sensor has the following design specifications:
The sensor shall be intialised using the following steps:
1. Initialize the control register values DIV, DCORRECT and CLKEN
2. Set control register field SRSTN to ’1’
3. Set control register field PDN to ’1’
The status register DATA value will not be updated with the current temperature reading approxi-
mately every 12th sensor clock cycle (sensor clock frequency is determined by the system clock fre-
quency and the control register DIV field).
When the status register field UPD is set to ’1’ then the result of the latest temperature measurement is
available in the DATA field. The value in the DATA field represents the current junction temperature
in degrees Celsius. Software can clear the UPD field in order to be able to detect when a new mea-
surement value is detected.
The status register also keeps track of the minimum and maximum DATA values that have been read
from the sensor.
A threshold (THRES) can be optionally defined and a alarm can be enabled via the control register
ALEN field. When ALEN is enabled then DATA will be compared with THRES every time a new
value is read from the sensor. If DATA >= THRES then the ALACT field of the status register will be
set to ’1’. The controller will generate an interrupt every time ALACT transitions from ’0’ to ’1’.
Software must clear the ALACT field for future threshold violations to generate interrupts.
Table 446.
Temperature sensor specifications
APB address offset
Value
Unit
Temperature measurement range
*
°
C
Sensitivity of temperature measurement
*
°
C
Maximum error in temperature after calibration across temperature range
*
°
C
Start-up time after PDN field in control register is set to ’1’
*
ms
Start-up time after SRSTN in control register is set to ’1’
*
Sensor clock cycles