MBED Example: How to use DS1620 Temperature Monitor

.from: http://www.frank-zhao.com/thingspeak_mbed_tut1/

#include "mbed.h"

#include "EthernetNetIf.h"

#include "NTPClient.h"

#include "HTTPClient.h"

// networking stuff

EthernetNetIf eth;

NTPClient ntp;

HTTPClient http;

char* ntpServerUrl = "0.ca.pool.ntp.org";

char* thingSpeakUrl = "http://api.thingspeak.com/update";

char* thingSpeakKey = "IS6YCLKIR423VO5H";

char urlBuffer[256];

char timeBuffer[64];

// pin defs

DigitalOut rst(p30);

DigitalOut clk(p29);

DigitalInOut dq(p28);

void DS1620Send(long data, int numOfBits)

{

    dq.output(); // we are sending

   

    for (int i = 0; i < numOfBits; i++)

    {

        clk = 0;

        wait_us(0.05);

        if (data & (1 << i)) // bit is 1

        {

            dq = 1;

        }

        else // bit is 0

        {

            dq = 0;

        }

        wait_us(0.5);

        clk = 1;

        wait_us(0.5);

    }

   

    dq.input(); // go back to being input

   

    clk = 1; // leave high

}

float DS1620ReadTemp()

{

    rst = 1;

    DS1620Send(0xAA, 8); // read temp command

   

    dq.input();

    int results = 0;

   

    // read in 9 bits

    for (int i = 0; i < 9; i++)

    {

        clk = 0;

        wait_us(0.5);

        clk = 1;

        wait_us(0.05);

        if (dq.read() != 0) // bit is 1

        {

            if (i < 8)

            {

                results |= 1 << i;

            }

            else

            {

                results *= -1; // last bit is sign bit

            }

        }

        wait_us(0.4);

    }

   

    clk = 1; // leave high

   

    rst = 0;

   

    return (float)results / 2; // div by 2 since last bit is 0.5

}

void DS1620Setup()

{

    // initial pin states

    rst = 0;

    clk = 1;

    dq.input();

    wait(0.1);

   

    rst = 1;

    DS1620Send(0x0A0C, 16); // config for continuous mode with CPU mode

    rst = 0;

    wait(0.1);

    rst = 1;

    DS1620Send(0xEE, 8); // start continuous conversions

    rst = 0;

    wait(0.1);

}

int main() {

    printf("Start\r\n");

    printf("Setting up Ethernet...\r\n");

    EthernetErr ethErr = eth.setup();

    if(ethErr)

    {

        printf("Error %d in ethernet setup.\r\n", ethErr);

        return -1;

    }

    printf("Ethernet setup OK\r\n");

   

    // get time from ntp

    time_t ctTime;

    Host server(IpAddr(), 123, ntpServerUrl);

    ntp.setTime(server);

   

    // start the sensor

    DS1620Setup();

   

    while(1)

    {

        // update data here

        ctTime = time(NULL);

        float temperature = DS1620ReadTemp();

       

        // format time here

        timeBuffer[0] = 0;

        strftime(timeBuffer, 64, "%Y-%m-%d %H:%M:%S", localtime(&ctTime));

       

        // for debug

        printf("Time: %s, Temperature: %f\r\n", timeBuffer, temperature);

       

        // format url here

        urlBuffer[0] = 0;

        sprintf(urlBuffer, "%s?key=%s&field1=%s&field2=%f", thingSpeakUrl, thingSpeakKey, timeBuffer, temperature);

        printf("Request to %s\r\n", urlBuffer);

       

        HTTPText resp;

        HTTPResult res = http.get(urlBuffer, &resp);

        if (res == HTTP_OK)

        {

            printf("Result :\"%s\"\r\n", resp.gets());

        }

        else

        {

            printf("Error %d\r\n", res);

        }

       

        wait(16); // limited by ThingSpeak's API

    }

   

    return 0;

   

}