Acquisition of temperature data to SD Card

I have managed to hack together from various sites a temperature data logger thats writes to a 2GB SD Card, firstly I had a blown up laptop motherboard and so I desoldered the SD card socket this was not very easy as they are surface mounted and is not designed to be removed. I then soldered 9 header pins to it and used a glue gun and melted glue all around the soldered part to strenghten it, afterwards I found a better way it was to use a MicroSD convertor to a standard SD card adaptor and soldered header pins to it.



or MicroSD adaptor



Library Used:

AF_SDLog library. from http://www.ladyada.net/make/gpsshield/download.html

I also have used the Sparkfun FAT16 library and examples <HERE> for use with there shield <HERE> and changed the '#define CS    8' on line 33 to '#define CS    10' in the examples to work with my build.

Code

/************************************/

/*            SD card temperature Logger         */

/*                             Version 1.e                          */

/*                           Chris Hawkins                      */

/************************************/

#include "AF_SDLog.h"

#include "util.h"

#include <avr/pgmspace.h>

AF_SDLog card;

File f;

#define ledBusyPin 8

#define powerPin 9

#define temperaturePin 0

#define BUFFSIZE 99

#define buttonStartStop 7

int buttonState = 0;         // current state of the button

int runState = false;     // previous state of the button

float lastPressed =0;

char buffer[BUFFSIZE];

uint8_t bufferidx = 0;

uint8_t i;

unsigned int logCount;

// blink out an error code

void error(uint8_t errno) {

while(1) {

for (i=0; i<errno; i++) {

digitalWrite(ledBusyPin, HIGH);

digitalWrite(powerPin, HIGH);

delay(200);

digitalWrite(ledBusyPin, LOW);

digitalWrite(powerPin, LOW);

delay(200);

}

for (; i<10; i++) {

delay(300);

}

}

}

void setup()

{

Serial.begin(9600);

putstring_nl("\r\nData logger");

// configure PINS

pinMode(ledBusyPin, OUTPUT);

pinMode(powerPin, OUTPUT);

pinMode(buttonStartStop, INPUT);

digitalWrite(powerPin, HIGH);

// check SD card - FAT 2GB

if (!card.init_card()) {

putstring_nl("Card init. failed!");

error(1);

}

if (!card.open_partition()) {

putstring_nl("No partition!");

error(2);

}

if (!card.open_filesys()) {

putstring_nl("Can't open filesys");

error(3);

}

if (!card.open_dir("/")) {

putstring_nl("Can't open /");

error(4);

}

// Check for next file in sequence 00 to 99

strcpy(buffer, "TMPLOG00.TXT");

for (buffer[6] = '0'; buffer[6] <= '9'; buffer[6]++) {

for (buffer[7] = '0'; buffer[7] <= '9'; buffer[7]++) {

putstring("\ntrying to open ");

Serial.println(buffer);

f = card.open_file(buffer);

if (!f)

break;

card.close_file(f);

}

if (!f)

break;

}

if(!card.create_file(buffer)) {

putstring("couldnt create ");

Serial.println(buffer);

error(5);

}

f = card.open_file(buffer);

if (!f) {

putstring("error opening ");

Serial.println(buffer);

card.close_file(f);

error(6);

}

putstring("writing to ");

Serial.println(buffer);

putstring_nl("ready!");

delay(250);

// clear buffer

strcpy(buffer,"");

}

void loop(){

// get button state

buttonState = digitalRead(buttonStartStop);

//  if button pressed and 2 seconds passed

if (buttonState ==HIGH && (millis() - lastPressed)>2000) {

lastPressed = millis();

runState = !runState;

}

// if the state has true then log temperature data

if (runState == true) {

// build string to write to card

sprintf(buffer, "%s,%d,%u,%d\n",getDate(),getTime (),logCount++,getTemperature());

//log data to SD Card

logData();

}

}

int getTemperature(){

//getting the voltage reading from the temperature sensor

float temperature = getVoltage(temperaturePin);

//converting from 10 mv per degree wit 500 mV offset

temperature =  (temperature - .5) * 100;

return temperature;

}

unsigned int getTime(){

//replace with RTC code once added

return  (millis() /1000);

}

char* getDate (){

//replace with RTC code once added

return "24/04/2010";

}

float getVoltage(int pin){

return (analogRead(pin) * .004882814); //converting from a 0 to 1024 digital range

// to 0 to 5 volts (each 1 reading equals ~ 5 millivolts

// using TMP36 temperature sensor

}

void logData( )

{

digitalWrite(ledBusyPin, HIGH);// LED on for witting to card

// get string length

bufferidx = strlen(buffer);

// write data to sd card

if(card.write_file(f, (uint8_t *) buffer, bufferidx) != bufferidx) {

putstring_nl("can't write!");

error(5);

}

digitalWrite(ledBusyPin, LOW);// LED off to show finished writting to card

}

/* End code */

Sample of output to SD card



Schematic