/**
* Called if a SYN packet was received
*
* @throws IOException
*/
protected void onEBusSyncReceived() throws IOException {
if (inputBuffer.position() == 1 && inputBuffer.get(0) == EBusTelegram.SYN) {
if (lockCounter > 0) lockCounter--;
logger.trace("Auto-SYN byte received");
// send a telegram from queue if available
send(false);
} else if (inputBuffer.position() == 2 && inputBuffer.get(0) == EBusTelegram.SYN) {
logger.warn("Collision on eBus detected (SYN DATA SYNC Sequence) ...");
blockNextSend = true;
// send a telegram from queue if available
send(false);
} else if (inputBuffer.position() < 5) {
if (lockCounter > 0) lockCounter--;
logger.trace("Telegram to small, skip!");
// send a telegram from queue if available
send(false);
} else {
if (lockCounter > 0) lockCounter--;
byte[] receivedTelegram = Arrays.copyOf(inputBuffer.array(), inputBuffer.position());
// send a telegram from queue if available, time critical!
send(false);
// After senden we can process the last received telegram
final EBusTelegram telegram = EBusUtils.processEBusData(receivedTelegram);
if (telegram != null) {
// execute event
onEBusTelegramReceived(telegram);
} else {
logger.debug("Received telegram was invalid, skip!");
}
}
// reset receive buffer
inputBuffer.clear();
}
/**
* Add a byte array to send queue.
*
* @param data
* @return
*/
public boolean send(byte[] data) {
if (data == null || data.length == 0) {
logger.debug("Send data is empty, skip");
return false;
}
byte crc = 0;
for (int i = 0; i < data.length - 1; i++) {
byte b = data[i];
crc = EBusUtils.crc8_tab(b, crc);
}
// replace crc with calculated value
data[data.length - 1] = crc;
return outputQueue.add(data);
}
/**
* Internal send function. Send and read to detect byte collisions.
*
* @param secondTry
* @throws IOException
*/
protected void send(boolean secondTry) throws IOException {
// blocked for this send slot because a collision
if (blockNextSend) {
logger.trace("Sender was blocked for this SYN ...");
blockNextSend = false;
return;
}
// currently no data to send
if (outputQueue.isEmpty()) {
logger.trace("Send buffer is empty, nothing to send...");
return;
}
// counter not zero, it's not allowed to send yet
if (lockCounter > 0) {
logger.trace("No access to ebus because the lock counter ...");
return;
}
byte[] dataOutputBuffer = outputQueue.peek();
logger.debug(
"EBusSerialPortEvent.send() data: {}", EBusUtils.toHexDumpString(dataOutputBuffer));
// clear first
inputBuffer.clear();
boolean isMasterAddr = EBusUtils.isMasterAddress(dataOutputBuffer[1]);
// send command
for (int i = 0; i < dataOutputBuffer.length; i++) {
byte b = dataOutputBuffer[i];
outputStream.write(b);
// directly read the current wrote byte from bus
int read = inputStream.read();
if (read != -1) {
byte r = (byte) (read & 0xFF);
inputBuffer.put(r);
// do arbitation on on first byte only
if (i == 0 && b != r) {
// written and read byte not identical, that's
// a collision
logger.warn("eBus collision detected!");
// last send try was a collision
if (lastSendCollisionDetected) {
logger.warn("A second collision occured!");
resetSend();
return;
}
// priority class identical
else if ((byte) (r & 0x0F) == (byte) (b & 0x0F)) {
logger.trace("Priority class match, restart after next SYN ...");
lastSendCollisionDetected = true;
} else {
logger.trace("Priority class doesn't match, blocked for next SYN ...");
blockNextSend = true;
}
// stop after a collision
return;
}
}
}
// sending master data finish
// reset global variables
lastSendCollisionDetected = false;
blockNextSend = false;
// if this telegram a broadcast?
if (dataOutputBuffer[1] == (byte) 0xFE) {
logger.warn("Broadcast send ..............");
// sende master sync
outputStream.write(EBusTelegram.SYN);
inputBuffer.put(EBusTelegram.SYN);
} else {
int read = inputStream.read();
if (read != -1) {
byte ack = (byte) (read & 0xFF);
inputBuffer.put(ack);
if (ack == EBusTelegram.ACK_OK) {
// if the telegram is a slave telegram we will
// get data from slave
if (!isMasterAddr) {
// len of answer
byte nn2 = (byte) (inputStream.read() & 0xFF);
inputBuffer.put(nn2);
byte crc = EBusUtils.crc8_tab(nn2, (byte) 0);
if (nn2 > 16) {
logger.warn("slave data to lang, invalid!");
// resend telegram (max. once)
if (!resend(secondTry)) return;
}
// read slave data, be aware of 0x0A bytes
while (nn2 > 0) {
byte d = (byte) (inputStream.read() & 0xFF);
inputBuffer.put(d);
crc = EBusUtils.crc8_tab(d, crc);
if (d != (byte) 0xA) {
nn2--;
}
}
// read slave crc
byte crc2 = (byte) (inputStream.read() & 0xFF);
inputBuffer.put(crc2);
// check slave crc
if (crc2 != crc) {
logger.warn("Slave CRC wrong, resend!");
// Resend telegram (max. once)
if (!resend(secondTry)) return;
}
// sende master sync
outputStream.write(EBusTelegram.ACK_OK);
inputBuffer.put(EBusTelegram.ACK_OK);
} // isMasterAddr check
// send SYN byte
outputStream.write(EBusTelegram.SYN);
inputBuffer.put(EBusTelegram.SYN);
} else if (ack == EBusTelegram.ACK_FAIL) {
// clear uncompleted telegram
inputBuffer.clear();
// resend telegram (max. once)
if (!resend(secondTry)) return;
} else if (ack == EBusTelegram.SYN) {
logger.warn("No answer from slave, skip ...");
// clear uncompleted telegram or it will result
// in uncomplete but valid telegram!
inputBuffer.clear();
resetSend();
return;
} else {
// Wow, wrong answer, and now?
logger.warn("Received wrong telegram: {}", EBusUtils.toHexDumpString(inputBuffer));
// clear uncompleted telegram
inputBuffer.clear();
// resend telegram (max. once)
if (!resend(secondTry)) return;
}
}
}
// after send process the received telegram
byte[] buffer = Arrays.copyOf(inputBuffer.array(), inputBuffer.position());
final EBusTelegram telegram = EBusUtils.processEBusData(buffer);
if (telegram != null) {
onEBusTelegramReceived(telegram);
} else {
logger.debug("Received telegram was invalid, skip!");
}
// reset send module
resetSend();
}