Matrix - Temperature Sensor

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1 Introduction

Temperature Sensor

We utilitze the DS18B20 in this module. The DS18B20 can be powered by its data line instead of an external power source. Each DS18B20 is assigned a unique ID. Its temperature range is -55 degree Celsius to +125 degree Celsius. The thermometer resolution is programmable from 9 to 12 bits. When the measured temperature is between -10 degree Celsius to +85 degree Celsius the accuracy can be at 0.5 degree. It uses the unique 1-wire interface which requires only one port pin for communication. Among all three DS18B20 pins V is power, G is ground and S is data

2 Features

• -55 degree Celsius to +125 degree Celsius
• One wire interface for communication
• Tiny, easy to be used in various situations
• 2.54mm spacing pin

3 How To

3.1 Connection

• Connect to Tiny4412 SDK (1506)

GND: Ground

VCC: 5V

S： GPIO_PIN1

3.2 Code Sample in C Under Linux

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "libfahw.h"
 
void parseCmd(int argc, char **argv, int *pin)
{
    int num = atoi(argv[1]);
    switch(num) {
    case 1:
        *pin = TINY4412_GPIO_PIN1;
        break;
    case 2:
        *pin = TINY4412_GPIO_PIN2;
        break;
    case 3:
        *pin = TINY4412_GPIO_PIN3;
        break;
    case 4:
        *pin = TINY4412_GPIO_PIN4;
        break;
    case 5:
        *pin = TINY4412_GPIO_PIN5;
        break;
    case 6:
        *pin = TINY4412_GPIO_PIN6;
        break;
    case 7:
        *pin = TINY4412_GPIO_PIN7;
        break;
    case 8:
        *pin = TINY4412_GPIO_PIN8;
        break;
    case 9:
        *pin = TINY4412_GPIO_PIN9;
        break;
    case 10:
        *pin = TINY4412_GPIO_PIN10;
        break;
    default:
        printf("Unsupported pin TINY4412_GPIO_PIN%d\n", num);
        num = 1;
        *pin = TINY4412_GPIO_PIN1;
        break;
    }
    printf("Using pin TINY4412_GPIO_PIN%d\n", num);
}
 
int main(int argc, char ** argv)
{
    int devFD = -1;
    int pin = TINY4412_GPIO_PIN1;
    char *temperature = (char *) malloc(32);
    memset(temperature, 0, 32);
 
    if (argc == 2) {
        parseCmd(argc, argv, &pin);
    } else {
        printf("Using default pin TINY4412_GPIO_PIN1\n");
    }
 
    if ((devFD = ds18b20Init(pin)) == -1) {
        printf("Fail to init ds18b20\n");
        return -1;
    }
    if (ds18b20Read(temperature) > 0) {
        printf("Temperature = %s\n", temperature);
    } else {
        printf("Fail to get temperature\n");
    }
    free(temperature);
    ds18b20DeInit(devFD);
    return 0;
}

3.3 Compile and Run

git clone http://github.com/friendlyarm/fa-hardware.git
cd fa-hardware
cd demo
cd matrix-temperature_sensor
make

Copy your compiled bin to your board and you are ready to go.