Guide

1/12/2018 mbed Starter Kit Experiment Guide - learn.sparkfun.com
https://learn.sparkfun.com/tutorials/mbed-starter-kit-experiment-guide/all 47/65
// Temperature logging demo - record temperatures to SD card and print them to
// the console every 10 seconds
#include "mbed.h"
#include "SDFileSystem.h"
// Analog input (pin 15)
AnalogIn ain(p15);
// USB serial (tx, rx)
Serial pc(USBTX, USBRX);
// SD card (SPI pins)
SDFileSystem sd(p5, p6, p7, p8, "sd");
// Timer for our timestamps
Timer timer;
int main() {
FILE *file;
float voltage_in;
float degrees_c;
int i;
int c;
// Start our timer
timer.start();
// Open file for writing
file = fopen("/sd/temp_data.txt", "w");
if ( file == NULL ) {
error("ERROR: Could not open file for writing!\n\r");
return -1;
}
// Tell the user we need to wait while we collect some data
pc.printf("\nCollecting data (Do not remove SD Card!) ...\n\r");
// Collect temperatures with timestamps every second
for(i = 0; i < 10; i++) {
voltage_in = ain * 3.3;
degrees_c = (voltage_in - 0.5) * 100.0;
fprintf(file, "%2.2fs: %3.1f deg C\n\r", timer.read(), degrees_c);
wait(1);
}
// Close file and re-open it for reading
fclose(file);
file = fopen("/sd/temp_data.txt", "r");
if ( file == NULL ) {
error("ERROR: Could not open file for reading!\n\r");
return -1;
}
// Print results to console
pc.printf("Temperature data:\n\r");
while(1) {
c = fgetc(file);
if ( c == EOF ) {
break;
}
pc.putc(c);
}
// Close the file and finish
fclose(file);
pc.printf("Done! Safe to remove SD card\n\r");
return 0;
}
Run
Windows
Compile the program and copy the downloaded file to the mbed.
Click the Windows Start button and search for “device manager.”