File content as of revision 4:b962f5a783a1:

#include "main.h"
#include "mbed.h"
#include "USBSerial.h"
#include "Adafruit_SSD1306.h"
#include "MPU6050_6Axis_MotionApps20.h"
#include "SDFileSystem.h"

//Virtual serial port over USB
#ifdef PC_DEBUG
USBSerial pc;
#endif

// Display
#ifdef OLED_DEBUG
SPI spi0(P0_9, NC, P0_10); // mosi, miso, sclk
Adafruit_SSD1306 oled(spi0, P0_11, P0_12, P0_13); // DC, RST, CS
#endif

// MPU
MPU6050 mpu;
InterruptIn dataReady(P0_15);

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

// LED for debug
DigitalOut led(LED1);

// Logging vars
FILE *logFile;

// Timer
Timer totalTime;
Timer captureTime;

// Switch
InterruptIn captureSwitch(P0_16);


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

// MPU control/status vars
bool dmpReady = false;  // set true if DMP init was successful
uint8_t mpuIntStatus;   // holds actual interrupt status byte from MPU
uint8_t devStatus;      // return status after each device operation (0 = success, !0 = error)
uint16_t packetSize;    // expected DMP packet size (default is 42 bytes)
uint16_t fifoCount;     // count of all bytes currently in FIFO
uint8_t fifoBuffer[64]; // FIFO storage buffer

// orientation/motion vars
Quaternion q;           // [w, x, y, z]         quaternion container
VectorInt16 aa;         // [x, y, z]            accel sensor measurements
VectorInt16 aaReal;     // [x, y, z]            gravity-free accel sensor measurements
VectorInt16 aaWorld;    // [x, y, z]            world-frame accel sensor measurements
VectorFloat gravity;    // [x, y, z]            gravity vector
float euler[3];         // [psi, theta, phi]    Euler angle container
float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector

// Forward declarations
void die(int flash_rate_s);
bool log_open();
void log_data(VectorInt16 data, Quaternion q);
void log_close();
void mpu_init();
void get_data();

volatile bool mpuInterrupt = false;
void dataReadyISR() {
    mpuInterrupt = true;
}

//void captureSwitchISR() {
//    // used for debouncing
//    static int prev_time = 0;
//
//    if (totalTime.read_ms() - prev_time < 200)
//        return;
//        
//    State = (State == IDLE) ? CAPTURE : IDLE;
//    prev_time = totalTime.read_ms();
//}

void captureSwitchISR() {
    // used for debouncing
    static int prev_time = 0;
    int curr_time = totalTime.read_ms();
    
    // Only change state after an amount of time
    // Note: abs value is necessary in case of 
    //   overflows
    if (abs(curr_time - prev_time) > 200)
        State = (State == IDLE) ? CAPTURE : IDLE;
        
    prev_time = curr_time;
}

int main(void)
{
    totalTime.start();
    
    State = IDLE;
    captureSwitch.mode(PullUp);
    captureSwitch.rise(captureSwitchISR);   
    
    OLED_PRINTP("Waiting to capture.     ",0,0);
    while (true) {
        if (State == CAPTURE) {
            PC_PRINTLN("Start capture button pressed!");
            OLED_CLEAR();
            OLED_PRINTPR("Starting capture.       ",0,0);
            
            // Start receiving data
            PC_PRINTLN("Opening log file...");
            if (!log_open()) {
                OLED_CLEAR();
                OLED_PRINTP("ERROR: SD (retry)", 0, 50);
                State = IDLE;
                continue;
            }
            
            PC_PRINTLN("Initializing MPU...");
            mpu_init();
            
            PC_PRINTLN("Starting capture...");
            OLED_PRINTPR("Capturing data...       ",0,0);
            captureTime.start();
            while (State == CAPTURE)
                get_data();
            OLED_PRINTPR("Finished capture.",0,0);
            
            log_close();
            captureTime.stop();
            captureTime.reset();
        }
    
        PC_PRINTLN("Idling...");
    }
}

/* 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);
    }
}

/* Returns false on failure, true otherwise */
bool log_open() {
    logFile = fopen(LOG_FILE, "a");
    if (logFile == NULL) {
        PC_PRINTLNF("SD card initialization error: Failed to open %s", LOG_FILE);
        return false;
    }
    fprintf(logFile, "---- BEGIN NEW DATASET ----\n");
    return true;
}

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

void mpu_init() {
    PC_PRINTLN("Initializing MPU");
    mpu.initialize();
    devStatus = mpu.dmpInitialize();
    
    if (devStatus == 0) {
        mpu.setDMPEnabled(true);
        packetSize = mpu.dmpGetFIFOPacketSize();
        
        PC_PRINTLN("DMP Initialized successfully!");
        dmpReady = true;
        dataReady.rise(dataReadyISR);
    } else { // ERROR
        PC_PRINTLNF("Error initializing MPU (code %d)", devStatus);
        die(DMP_ERROR_RATE);
    }
}

/* Requires the log to be open and mpu to be initialized*/
void get_data() {
    static uint32_t n_overflows = 0;
    //while (true) {
        //if (!dmpReady) break;   // do nothing if dmp not ready
        if (!dmpReady) return;
        
        while (!mpuInterrupt && fifoCount < packetSize);
        
        // Reset interrupt
        mpuInterrupt = false;
        mpuIntStatus = mpu.getIntStatus();

        // get current FIFO count
        fifoCount = mpu.getFIFOCount();
    
        // check for overflow (this should never happen unless our code is too inefficient)
        if ((mpuIntStatus & 0x10) || fifoCount == 1024) {
            PC_PRINTLNF("**** FIFO OVERFLOW @ %d ms ****", captureTime.read_ms());
            n_overflows++;
            // reset so we can continue cleanly
            mpu.resetFIFO();
            // otherwise, check for DMP data ready interrupt (this should happen frequently)
        } else if (mpuIntStatus & 0x02) {
            // Wait for a full packet - should be very short wait
            while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();
    
            // read a packet from FIFO
            mpu.getFIFOBytes(fifoBuffer, packetSize);
            fifoCount -= packetSize;
            
            // Get acceleration data
            mpu.dmpGetAccel(&aa, fifoBuffer);
            mpu.dmpGetQuaternion(&q, fifoBuffer);
//            mpu.dmpGetGravity(&gravity, &q);
//            mpu.dmpGetLinearAccel(&aaReal, &aa, &gravity);
//            mpu.dmpGetLinearAccelInWorld(&aaWorld, &aaReal, &q);
            
            PC_PRINTF("%d, ", aaWorld.x); PC_PRINTF("%d, ", aaWorld.y); PC_PRINTLNF("%d", aaWorld.z);
            
//            OLED_SETCURS(0, 10); OLED_PRINTF("%d, ", aaWorld.x); OLED_PRINTF("%d, ", aaWorld.y); OLED_PRINTLNF("%d", aaWorld.z);
            
            fprintf(logFile, "%u,%d,%d,%d,%f,%f,%f,%f,%u\n", captureTime.read_ms(), aa.x, aa.y, aa.z, q.x, q.y, q.z, q.w, n_overflows);
        //}
    }
}

void log_data(VectorInt16 data, Quaternion q) {
    fprintf(logFile, "%d,%d,%d,%d,%f,%f,%f,%f\n", captureTime.read_ms(), data.x, data.y, data.z, q.x, q.y, q.z, q.w);
}