Interfacing nRF52832 with ds18b20

[Arun0498]

Hello guys,

                 I'm trying to interface nrf52832 with ds18b20 temperature sensor and I'm using this code https://github.com/sigurdnev/Nordic-DS18B20 and I'm getting the output value but sometimes I'm getting temperature value as -0.063 and sometimes some random values I'm completely new to nRF so I don't know what I'm doing wrong

[Sigurd]

Hi,

Are you running any BLE roles at the same time? (advertising,scanner,central/peripheral connection)?

[Arun0498]

Hi,

No I'm just using GPIO only

[Sigurd]

How does your main.c file look like? is it 100% the same as the example main.c ?

The example is very basic, and in a normal application, you likely want to trigger the reading in a app_timer callback so that the GPIO reading happens at a higher priority level, so that it's not preempted by other interrupts.

[Arun0498]

Hi,

After your suggestion I added app_timer in the main.c  but I'm getting an error, I have added the images of the main code and the error I got, Can you tell why I'm  doing wrong

[Sigurd]

From the screenshots, it looks like you used the example from github(without modification) when you experienced this issue. In that case, there should not be any interrupts happening, that could cause the GPIO reading/writing timing to fail. You could try to start the HFCLK from the crystal oscillator, and see if that makes any difference. Also check the wiring to the sensor, and make sure they are all properly connected.

  // Start HFCLK from crystal oscillator
  NRF_CLOCK->TASKS_HFCLKSTART = 1;
  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

[Arun0498]

Ok this is what I have tried, and this is my main.c

/**
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#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "app_timer.h"
#include "nrf_drv_clock.h"

#include <stdio.h>

#include "ds18b20.h"

//Datasheet: https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf

static float temp = 0;

static void lfclk_request(void)
{
    ret_code_t err_code = nrf_drv_clock_init();
    APP_ERROR_CHECK(err_code);
    nrf_drv_clock_lfclk_request(NULL);
}

APP_TIMER_DEF(m_repeated_timer_id);//ADDED

/*static void repeated_timer_handler(void * p_context)
{
    nrf_drv_gpiote_out_toggle(LED_1);
}*/

static void timers_init(void)
{
    ret_code_t err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
}

/*static void app_create_timers()
{
    ret_code_t err_code;

    // Create timers
    err_code = app_timer_create(&m_repeated_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                ds18b20_get_temp_method_2);
    APP_ERROR_CHECK(err_code);
    return;
}*/

void main()
{
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
    lfclk_request();
    timers_init();
    ds18b20_setResolution(12);

   //temp = ds18b20_get_temp_method_2();
   //printf("Temperature: %.3f \r\n", temp);

    while(1)
    {   
        NRF_CLOCK->TASKS_HFCLKSTART = 1;
        while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
        nrf_delay_ms(2000);
        timers_init();
        temp =app_timer_start(&m_repeated_timer_id, APP_TIMER_MODE_REPEATED,ds18b20_get_temp_method_2);
        //ret_code_t err_code =app_timer_start(&m_repeated_timer_id, APP_TIMER_MODE_REPEATED,ds18b20_get_temp_method_2); 
        APP_ERROR_CHECK(temp);
        //temp = app_timer_stop(&m_repeated_timer_id, APP_TIMER_MODE_REPEATED,ds18b20_get_temp_method_2);
        APP_ERROR_CHECK(temp);
        //temp = app_timer_start(m_repeated_timer_id,APP_TIMER_TICKS(0),NULL); // timer for 3secs
        //APP_ERROR_CHECK(temp);
        //temp = ds18b20_get_temp_method_2();
        //temp = ds18b20_get_temp();
        printf("Temperature: %.3f \r\n", temp);
       
    }
}


/** @} */