Measuring temperature using the sensor in nRF52832

[jinvers]

Hello,

In an application with the nRF52832, Softdevice and SDK 17.1.0 I try to use the temperature sensor according to the peripheral example. I attach the temperature.c file code.

#include <stdint.h>
#include "nrf_temp.h"

// Function to initialize and read temperature from the TEMP peripheral using SDK functions
int32_t nrf_read_temperature(void) {
   int32_t temp;

   nrf_temp_init();

   NRF_TEMP->TASKS_START = 1; /** Start the temperature measurement. */

   /* Busy wait while temperature measurement is not finished, you can skip waiting if you enable interrupt for DATARDY event and read the result in the interrupt. */
   /* A zero has been given as right argument to operator '|'" */
   while (NRF_TEMP->EVENTS_DATARDY == 0)
   {
        // Do nothing.
   }
    NRF_TEMP->EVENTS_DATARDY = 0;

   /**@note Workaround for PAN_028 rev2.0A anomaly 29 - TEMP: Stop task clears the TEMP register. */
   temp = (nrf_temp_read() / 4);

    /**@note Workaround for PAN_028 rev2.0A anomaly 30 - TEMP: Temp module analog front end does not power down when DATARDY event occurs. */
    NRF_TEMP->TASKS_STOP = 1; /** Stop the temperature measurement. */

    return (temp);
    }

However, I have problems executing the nrf_read_temperature() function because the program breaks without an specific reason. Should I use another code? Any suggestion?

Thank you very much in advance.

Regards,

Joel

[Hung Bui]

Hi Joel, 
If you have a look here: https://docs.nordicsemi.com/bundle/sds_s140/page/SDS/s1xx/sd_resource_reqs/hw_block_interrupt_vector.html

You will find that the TEMP peripheral is "restricted" when the softdevice is active. 

You would need to use softdevice provided API to access it. Please use sd_temp_get() function. 
Here is an example code: 

    int temp;
    uint32_t err;
    err=sd_temp_get(&temp);
    APP_ERROR_CHECK(err);
    NRF_LOG_INFO("temp: %d",temp);

You should call it after the softdevice is enabled. 

[jinvers]

Hi,

Thank you. I will check it tomorrow.

Regards,

Joel

[jinvers]

In fact the raw data fluctuates between 104 and 112.

Regards,

Joel

[Hung Bui]

Hi,
If you look at the specification you can find that the unit of TEMP peripheral is 0.25oC. 112 = 28oC which is quite high, but maybe it's just because in Spain it is warmer than in Norway? 

[jinvers]

Hi,
Thank you.
The chip is assembled in a PCB and perhapsis measuring some degrees more than ambient. I suppose it will be necessary some calibration or offset compensation.

Regards,

Joel

[Hung Bui]

Hi Joel, 
You are right. The spec stated that "Linearity compensation can be implemented if required by the application." So yes, calibration maybe needed. But it's lineal offset so it should straight forward. 

[jinvers]

Ok. Thank you very much.

Regards,

Joel