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This demo will show you how to use TPM36 sensor to get the temperature value.

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1. 96board
2. Liner Base Mezzanine Card
3. 4-pin cable
4. TPM36 temperature sensor

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Connect

Connect TMP36 sensor to ADC1 port using 4-pin cable.

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <linux/spi/spidev.h>
#include <linux/types.h>
#include <inttypes.h>

#include "libsoc_spi.h"
#include "libsoc_gpio.h"
#include "libsoc_debug.h"

#define GPIO_CS 18

static uint8_t tx[3],rx[3];

int main()
{
    int adc_value;
    gpio *gpio_cs;
    libsoc_set_debug(0);
    gpio_cs = libsoc_gpio_request(GPIO_CS,LS_SHARED);
    if(gpio_cs == NULL)
    {
	goto fail;
    }
    libsoc_gpio_set_direction(gpio_cs,OUTPUT);
    if(libsoc_gpio_get_direction(gpio_cs) != OUTPUT)
    {
	printf("Failed to set direction to OUTPUT!\n");
	goto fail;	
    }
    spi *spi_dev = libsoc_spi_init(32766,0);   
    
   if(!spi_dev)
   {
	printf("Failed to get spidev device!\n");
   	return EXIT_FAILURE;
   }
   libsoc_spi_set_mode(spi_dev,MODE_0);
   libsoc_spi_get_mode(spi_dev);
   libsoc_spi_set_speed(spi_dev,10000);
   libsoc_spi_get_speed(spi_dev);
   libsoc_spi_set_bits_per_word(spi_dev,BITS_8);
   libsoc_spi_get_bits_per_word(spi_dev);

   tx[0] = 0x01;
   tx[1] = 0x80;
   tx[2] = 0x00;
   while(1)
   {
	libsoc_gpio_set_level(gpio_cs,HIGH);
	usleep(10);
	libsoc_gpio_set_level(gpio_cs,LOW);
     	libsoc_spi_rw(spi_dev,tx,rx,3);
   	libsoc_gpio_set_level(gpio_cs,HIGH);

	adc_value = (rx[1]<<8)&0b1100000000;
	adc_value |= (rx[2]&0xff);

	printf("The current temperature is %2.1f\n",(adc_value*5.0/1023-0.5)*100);
	sleep(1);
   }
   free:
   libsoc_spi_free(spi_dev);
   fail:
   if(gpio_cs)
   {
	libsoc_gpio_free(gpio_cs);
   }
   return EXIT_SUCCESS;
}

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gcc temp.c -o temp -lsoc
sudo ./temp

Change the temperature, the value printed on the terminal also will change.

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