eImp_SPI_PN532

// Transmit data between  NFC reader and Planner


const PN532_PREAMBLE= 0x00;
const PN532_STARTCODE1= 0x00;
const PN532_STARTCODE2= 0xFF;
const PN532_POSTAMBLE= 0x00;

const PN532_HOSTTOPN532= 0xD4;

const PN532_FIRMWAREVERSION= 0x02;
const PN532_GETGENERALSTATUS= 0x04;
const PN532_SAMCONFIGURATION=  0x14;
const PN532_INLISTPASSIVETARGET= 0x4A;
const PN532_RFCONFIGURATION=       0x32;
const PN532_INDATAEXCHANGE= 0x40;
const PN532_MIFARE_READ= 0x30;
const PN532_MIFARE_WRITE= 0xA0;

const PN532_AUTH_WITH_KEYA= 0x60;
const PN532_AUTH_WITH_KEYB= 0x61;


const PN532_WAKEUP= 0x55;

const  PN532_SPI_STATREAD= 0x02;
const  PN532_SPI_DATAWRITE= 0x01;
const  PN532_SPI_DATAREAD= 0x03;
const  PN532_SPI_READY= 0x01;

const PN532_MIFARE_ISO14443A= 0x0;
const PN532_MAX_RETRIES= 0x05;
local pn532ack = [0x00, 0x00, 0xFF, 0x00, 0xFF, 0x00];
local pn532response_firmwarevers = [0x00, 0xFF, 0x06, 0xFA, 0xD5, 0x03];


local tagId=""

function intToHex(inputByte) //assumes 1 byte value 0-255
{
    local result = "";
    if ((inputByte>255)||(inputByte<0)) return "00";
    local digit= inputByte/16; //high nibble
    if (digit<10) result=digit.tostring();
    else {
        digit=(0x41 + digit-10) //"A"..."F"
        result=digit.tochar();
    }
    digit= inputByte%16;  //low nibble
    if (digit<10) result+=digit.tostring();
    else {
        digit=(0x41 + digit-10) //"A"..."F"
        result+=digit.tochar();
    }
    return result;
}


function begin() {
    hardware.pin1.write(0);//pull CS low
    imp.sleep(1);
    // not exactly sure why but we have to send a dummy command to get synced up
    sendCommandCheckAck([PN532_FIRMWAREVERSION], 1, 100);
    // ignore response!
}

function RFConfiguration(mxRtyPassiveActivation) {
	sendCommandCheckAck([PN532_RFCONFIGURATION, PN532_MAX_RETRIES, 0xFF, 0x01, mxRtyPassiveActivation], 5,100);
    server.show("RFConfiguration")
    // ignore response!
}

function startNFC(){
  begin();
  RFConfiguration(0x14); // default is 0xFF (try forever; ultimately it does time out but after a long while
  local versiondata = getFirmwareVersion();
  if (! versiondata) {
    server.show("Didn't find PN53x board");
  }else {
    // Got ok data, print it out!
    server.show("Found chip PN5");
    server.show(versiondata);

   // nfc.SAMConfig();
  }
}

function getFirmwareVersion() {
    local response;
    local buf=[0,1,2,3,4,5,6,7,8,9,10,11];

    if (! sendCommandCheckAck([PN532_FIRMWAREVERSION], 1,100))
        return 0;
    // read data packet
    readspidata(buf, 12);
    // check some basic stuff
    for (local i=0; i<6; i++) {
        if (buf[i] != pn532response_firmwarevers[i]) return false;
    }

    response = buf[6];
    response = response<<8;
    response += buf[7];
    response = response<<8;
    response += buf[8];
    response = response<<8;
    response += buf[9];

    return response;
}






function sendCommandCheckAck(cmd, cmdlen, timeout) {
    local timer = 0;

    // write the command
    spiwritecommand(cmd, cmdlen);

    // Wait for chip to say its ready!
    while (readspistatus() != PN532_SPI_READY) {
        if (timeout != 0) {
            timer+=10;
            if (timer > timeout){
                server.show("No response READY");
                return false;
            }
        }
        imp.sleep(0.01);
    }

    // read acknowledgement
    if (!spi_readack()) {
        server.show("Wrong ACK");
        return false;
    }

    timer = 0;
    // Wait for chip to say its ready!
    while (readspistatus() != PN532_SPI_READY) {
        if (timeout != 0) {
            timer+=10;
            if (timer > timeout)
                return false;
        }
        imp.sleep(0.01);
    }

    return true; // ack'd command
}


function spi_readack() {
    local ackbuff =[0,1,2,3,4,5];

    readspidata(ackbuff, 6);
    for (local i=0; i<6; i++) {
        if (ackbuff[i] != pn532ack[i]) return false;
    }
    return true;
}

function readspidata(buff, length) {
    hardware.pin1.write(0);//pull CS low
    imp.sleep(0.002);
    spiwrite(PN532_SPI_DATAREAD); //read leading byte DR and discard

    for (local i=0; i<length; i++) {
        imp.sleep(0.001);
        buff[i] = spiwrite(PN532_SPI_STATREAD);
        server.show(buff[i]);
    }
    hardware.pin1.write(1);//pull CS high

}

function readspistatus() {
    hardware.pin1.write(0);//pull CS low
    imp.sleep(0.002);
    spiwrite(PN532_SPI_STATREAD);
    local value= hardware.spi257.read(1);
    hardware.pin1.write(1);//pull CS high
    return value;

}


function spiwritecommand(cmd, cmdlen) {
    local checksum;
    hardware.pin1.write(0);//pull CS low
    imp.sleep(0.002);
    cmdlen++;

    spiwrite(PN532_SPI_DATAWRITE);

    checksum = PN532_PREAMBLE + PN532_PREAMBLE + PN532_STARTCODE2;
    spiwrite(PN532_PREAMBLE);
    spiwrite(PN532_PREAMBLE);
    spiwrite(PN532_STARTCODE2);

    spiwrite(cmdlen);
    local cmdlen_1=256-cmdlen;
    spiwrite(cmdlen_1);

    spiwrite(PN532_HOSTTOPN532);
    checksum += PN532_HOSTTOPN532;

    for (local i=0; i<cmdlen-1; i++) {
        spiwrite(cmd[i]);
        checksum += cmd[i];
    }
    checksum%=256;
    local checksum_1=255-checksum;
    spiwrite(checksum_1);
    spiwrite(PN532_POSTAMBLE);

    hardware.pin1.write(1);//pull CS high

}

function spiwrite(byte){

    local tempString="\\x"+intToHex(byte);
    hardware.spi257.write(tempString);
    local resp=hardware.spi257.read(1);
    foreach(i, val in resp){
            server.show(tempString +"-> (" +resp.len() + ") ");
            server.log(val);
    }

    return resp; //read n bytes


}



function initSPI()
{
    hardware.configure(SPI_257);
    hardware.spi257.configure(LSB_FIRST| CLOCK_IDLE_HIGH  , 4000); // Configure SPI_257 at about 4MHz   | CLOCK_IDLE_LOW
    hardware.pin1.configure(DIGITAL_OUT); //Configure the chip select pin
    hardware.pin1.write(1);//pull CS high
    imp.sleep(0.1);//wait 100 ms
    hardware.pin1.write(0); //pull CS low to start the transmission of temp data
    server.show("init ok");
}




// This is where our program actually starts! Previous stuff was all function and variable declaration.
// This'll configure our impee. It's name is "UartCrossAir", and it has both an input and output to be connected:
imp.configure("remoteNFC", [], []);
initSPI(); // Initialize the SPI, called just once
startNFC();

// The end