Silicon die temperature value interpretation

[Sébastien Despont]

Dear Nordic Developer Zone,

I am able to ask a Silicon temperature measurement, but not to correctly interpret the answer.

After last measurement, I have got 0x29C. In your documentation, you specify that the value has 0.25°C precision. Therefore : 0x29C = 668 --> Temperature : 668 / 4 = 167, so 16.7°C???

Seems low. Can you help me to understand how to interpret this result?

I am using nRF51822 with SoftDevice

Best regards

[Håkon Alseth]

Hi Sébastien,

It seems that your temperature is very off, as it indicates 167 degrees. Mine indicates 39 degrees (around 16 degrees offset) Are you using the "temperature_example" in the SDK and seeing these numbers?

There are some anomalies on this peripheral, which is covered in the PAN-028 document: www.nordicsemi.com/.../76230321

The temperature sensor should give out a 10 bit 2’s compliment value but if you use the temperature_example in the SDK the output will be 32 bit 2’s compliment value. To find the actual deg C temperature value you should divide the TEMP output value with 4, as done in the temperature_example in the SDK.

The error read on the TEMP peripheral should be pure offset error. You can calibrate the temperature value in software, i.e. if you know the temperature in your room, just add or subtract from the measured value to get the correct value.

Best regards Håkon