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ADC Temperature Sensor Issue- S7G2

Latest Updated:07/09/2016

Question:

I'm seeing an issue with the temperature sensor on the Synergy S7G2 in SSP 1.1.0. Is there an issue?

Answer:

The issue with the S7G2 temperature sensor is that the Sample State Register has not been properly set. You may see an issue such as the following. When converting, in sequence, an analog channel (example: channel 0) and the temperature sensor, the temperature sensor output seems to be directly proportional to the analog channel value.

Explanation of Issue:

Normally the Sample States for any channel has to be set by the user using the sampleStateCountSet() function since the number of sample states is dependent on the input impedance for whatever voltage source the ADC is measuring. But since the Temperature sensor is an internal device with a known impedance, the driver should have set the Sample State Count for the Temperature sensor. This will be fixed for the next major release, currently scheduled for Early 2017.

Current Work Around:

For now, you can resolve the issue by using the sampleStateCountSet() function to change the Sample States Count for the Temperature Sensor.

adc_sample_state_t tempsensor_sample_state = {ADC_SAMPLE_STATE_TEMPERATURE, 0x80};
err = g_adc0.p_api->sampleStateCountSet(g_adc0.p_ctrl, &tempsensor_sample_state);

Make that function call after the scanCfg() function is called.

Synergy S7G2