File content as of revision 1:93723df61425:

#include "main.h"
#include "mbed.h"
#include "rtos.h"
#include "USBSerial.h"
#include "Adafruit_SSD1306.h"
#include "MPU6050_6Axis_MotionApps20.h"
#include "SDFileSystem.h"
#include "output.h"
#include "threads.h"
#include "signals.h"

// SD Card
SDFileSystem sd(P0_21, P0_22, P1_15, P1_19, "sd"); // MOSI, MISO, SCLK, SSEL SPI1

// LED for debug
DigitalOut led(LED1);

// Timer
Timer totalTime;
Timer captureTime;

// Switch
InterruptIn captureSwitch(P0_16);

// Main thread reference
osThreadId mainThreadID;

// State
enum state {IDLE, CAPTURE};
enum state State;

// Forward declarations
void die(int flash_rate_s);
bool log_open();
void log_close();

void captureSwitchISR() {
    // used for debouncing
    static int prev_time = 0;

    if (totalTime.read_ms() - prev_time < 200)
        return;
        
//    State = (State == IDLE) ? CAPTURE : IDLE;
    osSignalSet(mainThreadID, SIG_CAPTURE);
    prev_time = totalTime.read_ms();
}

int main(void)
{
    totalTime.start();
    
    captureSwitch.mode(PullUp);
    captureSwitch.rise(captureSwitchISR);   
    
    mainThreadID = osThreadGetId();

    while (true) {
        Thread::wait(SIG_CAPTURE);
        
        FILE *logfile = log_open();
        Thread get_data_thread(get_data, logfile, osPriority priority=osPriorityHigh, DEFAULT_STACK_SIZE, NULL);
        
        Thread::wait(SIG_CAPTURE);

        get_data.terminate();
    }
}

/* Halts program and flashes LED at specified rate */
void die(int flash_rate_s) {
    while (1) {
        led = 1;
        wait(flash_rate_s/2);
        led = 0;
        wait(flash_rate_s/2);
    }
}

/* Blocks until logfile is successfully opened
 * There are cases where this will hang forever and need to reset (unavoidable) */
FILE *log_open() {
    FILE *logFile = fopen(LOG_FILE, "a");
    while (logFile == NULL) {
        PC_PRINTLN("Error opening SD card!");
        OLED_PRINTP("ERROR: SD (retry?)", 0, 50);
    }
    return logFile;
}

void log_close() {
    if (logFile != NULL)
        fclose(logFile);
}

void log_acceleration(VectorInt16 data) {
    fprintf(logFile, "%d, %d,%d,%d\n", captureTime.read_ms(), data.x, data.y, data.z);
}