SoM Temperature Sensor¶

The MitySOM-5CSX features a digital thermal sensor (U14) that is placed on the bottom side of the module below the Cyclone V SoC near the rear edge of the module. This sensor measures an overall module temperature and not that of any single component.

Updated Temperature Sensor, LM73CIMK-1¶

Starting at the end of 2014, the temperature sensor was updated to a better part. The LM73CIMK-1 temperature sensor on
"dash 2" assemblies (part numbers ending in -2 or newer, such as 80-000642RC-2) is attached to the I2C0 bus at address 1001100 (0x4C).

The LM73 temperature sensor is defined in the Dev Kit Device Tree and can be read through the file system following the example below.

root@mitysom-5csx:~# cat /sys/class/hwmon/hwmon0/temp1_input
35250

The temperature result in returned in millidegrees C.

80-000642Rx-1 Temperature Sensor, TC74A5¶

The revision 1 modules include a TC74A5 temperature sensor. This device is attached to the I2C0 bus at address 1001101 (0x4D).
As of late 2014, the temperature sensor was replaced on new assembly versions of the MitySOM-5CSx.

Example SW Code¶

As a part of our MitySOM-5CSX Development Kit the filesystem on the SD card includes a "tc74" application that can be run to read the temperature sensor. Note that the binary is located under the /usr/bin/ directory of the file system. Below is an example command to run the application:

root@mitysom-5csx:~# tc74 -b 0 temp
Temperature = 49°C

The .cpp and .h files that makeup this sample application are attached to the page as well for your reference (tc74_source.zip).

Building sample code¶

If you want to rebuild the sample application from the source code provided perform the following command from your environment that is configured for the MitySOM-5CSX:

arm-linux-gnueabihf-g++ -DTC74_APP -o tc74 i2cdevice.cpp tc74.cpp