File content as of revision 2:fc86438b206f:

#include "pixy.h"

pixySPI::pixySPI(PinName mosi, PinName miso, PinName sclk, int nBlocks, Serial* ser)
{
    spi=new SPI(mosi,miso,sclk); //the default spi settings will work fine here
    spi->format(8,0); //8bits mode 0
    spi->frequency(100000); //set the frequency in Hz
    sync=0xAA55; //start word of a frame coming from the pixy
    debug=ser; //debug connection
    blocks=new Block[nBlocks]; //allocate space for the blocks
    numBlocks=nBlocks;
}

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


short pixySPI::readTwoBytesLSB()
{
    short out;
    char read[2]= {0,0};
    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);
    }
}

void pixySPI::capture()
{
    memset(blocks, 0, numBlocks*sizeof(Block));
    for (int i=0; i<numBlocks; ++i) {
        Block* out=&blocks[i];
        out->signature=INVALID_BLOCK;
        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) || checksum==0) {
            //debug->printf("checksum doesn't add up %d\n", checksum);
            out->signature=INVALID_BLOCK; //used for invalid signatures
        }
        //debug->printf("found block\n");
    }
    return;
}

Block* pixySPI::getBlocks()
{
    return blocks;
}

int pixySPI::getNumBlocks()
{
    return numBlocks;
}

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