RE: Internal temperature measurement with Zephyr

Peter_S — Fri, 20 Jan 2023 13:56:32 GMT

Hi, Jørgen here is code that uses sensor_sample_fetch_chan():

#include <zephyr/zephyr.h>
#include <zephyr/device.h>
#include <zephyr/drivers/sensor.h>
#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(Info, LOG_LEVEL_INF);

static const struct device *temp_dev = DEVICE_DT_GET_ANY(nordic_nrf_temp);

/*** Time measure functions ***/
void Duration_Timer_Init()
{
	NRF_TIMER4->TASKS_START = 1;
	NRF_TIMER4->PRESCALER = 1;
}

void Duration_Timer_Start()
{
	NRF_TIMER4->TASKS_CLEAR = 1;
	NRF_TIMER4->TASKS_CAPTURE[0] = 1;
}

void Duration_Timer_Stop()
{
	NRF_TIMER4->TASKS_CAPTURE[1] = 1;
	uint32_t start = NRF_TIMER4->CC[0];
	uint32_t stop = NRF_TIMER4->CC[1];
	LOG_INF("Function duration [us]: %d", (stop - start) >> 3);	
}

/*** Performs a temperature measurement of the MCU and returns its value in degrees C ***/
static int16_t Temperature_Sensor_Get_Data()
{
	struct sensor_value temp_value;
	int err;

	Duration_Timer_Start();
    err = sensor_sample_fetch_chan(temp_dev, SENSOR_CHAN_DIE_TEMP);
	Duration_Timer_Stop();

    if(err) 
        LOG_ERR("sensor_sample_fetch failed with error: %d", err);

    err = sensor_channel_get(temp_dev, SENSOR_CHAN_DIE_TEMP, &temp_value);
    if(err) 
        LOG_ERR("sensor_channel_get failed with error: %d", err);

    return temp_value.val1;
}

/*** Main ***/
void main(void)
{
	Duration_Timer_Init();

	while(1)
	{
		k_msleep(1000);
		LOG_INF("MCU temperature [C]: %d", Temperature_Sensor_Get_Data());
	}
}

and here is the log:

[00:00:02.001,159] <inf> Info: Function duration [us]: 480
[00:00:02.001,190] <inf> Info: MCU temperature [C]: 23
[00:00:03.001,739] <inf> Info: Function duration [us]: 481
[00:00:03.001,770] <inf> Info: MCU temperature [C]: 23
[00:00:04.002,319] <inf> Info: Function duration [us]: 480
[00:00:04.002,319] <inf> Info: MCU temperature [C]: 23

prj.conf:

CONFIG_USE_SEGGER_RTT=y
CONFIG_LOG=y
CONFIG_LOG_BACKEND_SHOW_COLOR=y

# Enable multithreading
CONFIG_MULTITHREADING=y

# TIMER 4
CONFIG_NRFX_TIMER4=y

# Sensor
CONFIG_SENSOR=y

# Enable internal oscillator
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

# Enable MPU
CONFIG_ARM_MPU=y

# Enable hardware stack protection
CONFIG_HW_STACK_PROTECTION=y

# Configure GPIO as pin RESET
CONFIG_GPIO_AS_PINRESET=y

I don't know why, but it seems that the addition of the CONFIG_BT=y in the prj.conf reduces the duration of this function from 480 us to 38 us. The mpsl_temperature_get() also takes 38 us. The problem seems to be solved, thank you for your help.

RE: Internal temperature measurement with Zephyr

Jørgen Holmefjord — Thu, 19 Jan 2023 17:08:42 GMT

Hi,

If you are planning to add BLE functionality to the project, can you check if mpsl_temperature_get() gives faster run time?

400us sound very long for getting a temperature reading. Can you post the sample you used for testing this?

Best regards,
Jørgen