Uart loopback test

TyreBiter

I am trying to connect two javelin processors together using the Uart class. I thought that I might be able to test and develop a communication interface on one javelin by connecting the transmit to the receive pins with the appropriate resistors and signal diodes.

It appears not to work.

Am I expecting too much of the uart virtual peripheral system? Or is there possibly another problem?

Peter Verkaik

To test a serial protocol, just connect the tx pin, via a 1k resistor, to the rx pin.

static final int rxpin = CPU.pin1;

static final int txpin = CPU.pin0;



static Uart txUart = new Uart(Uart.dirTransmit,txpin,Uart.dontInvert,Uart.speed1200,Uart.stop1);

static Uart rxUart = new Uart(Uart.dirReceive,rxpin,Uart.dontInvert,Uart.speed1200,Uart.stop1);


static void main() {
int count = 25; char rxchar = 0; char txchar = 0;
· while (true) {
··· if (rxUart.byteAvailable()) {
······rxchar = rxUart.receiveByte();·//receive
····· System.out.print(rxchar); //should be 'A' to 'Z' repeatedly
··· }
··· CPU.delay(10500); //wait 1 second
··· count = (count+1) % 26;
··· txchar = (char)(count+ 0x41); //send 'A' to 'Z' repeatedly
··· txUart.sendByte(txchar);
· }
}

regards peter