File content as of revision 0:1b99a0bee9e0:

#include "pixy.h"

pixySPI::pixySPI(PinName mosi, PinName miso, PinName sclk, Serial* ser)
{
    spi=new SPI(mosi,miso,sclk); //the default spi settings will work fine here
    spi->format(8,0);
    spi->frequency(100000);
    sync=0xAA55;
    debug=ser;
}

pixySPI::~pixySPI()
{
    delete spi;
}


short pixySPI::readTwoBytesLSB()
{
    short out;
    char read[2];
    read[0]=spi->write(0x00);
    read[1]=spi->write(0x00);
    out=(((short)read[0]) << 8) | read[1];
    return out;
}


//this doesn't work
void pixySPI::readNBytes(char* buf, int num)
{
    for (int i=0; i<num; i++) {
        char byte=spi->write(0x00);
        debug->printf("%X\n", byte);
        memcpy(buf+i, &byte, 1);
    }
}

Block pixySPI::getBlock(Serial* debug)
{
    Block out;
    uint16_t checksum=0;
    //first we need to detect the start of a block. They all start with 0xAA55
    char frame[2]= {0,0}; //this is a 2 byte running frame of what is being recieved. It's like a first-in-last-out queue
    //debug->printf("looking for valid signature\n");
    while (memcmp((char*)&sync, frame, 2)!=0) {
        frame[0]=frame[1]; //move byte down
        frame[1]=spi->write(0x00); //get next byte.
    }
    spi->write(0x00);
    //ok so we got a valid signature
    //these didn't end up working
    //readNBytes((char*)(&checksum), 2); //get the checksum
    //readNBytes((char*)(&out), sizeof(Block)); //get the rest of the data
    checksum=readTwoBytesLSB();
    out.signature=readTwoBytesLSB();
    out.x=readTwoBytesLSB();
    out.y=readTwoBytesLSB();
    out.width=readTwoBytesLSB();
    out.height=readTwoBytesLSB();
    
    if (checksum!=(out.x+out.y+out.signature+out.width+out.height)) {
        //debug->printf("checksum doesn't add up %d\n", checksum);
        out.signature=20; //used for invalid signatures
    }
    return out;
}

char pixySPI::getRawData()
{
    return spi->write(0x00);
}