Serial Communication issues with python (at Mac) and Energia

[lilyhack 3]

I have an XBee (S2C) connected to my Mac and another XBee connected to a TI microcontroller (TIVA-C129) communicating with each other - Mac as a coordinator and TI as a router.

I can communicate between them, but on the TI side, I can't read the exact data that is coming in the serial port.

On the Mac, I am running below python code that reads the incoming serial data through XBee and writes an acknowledgment.

#!/usr/bin/python
import serial

ser = serial.Serial('/dev/tty.usbserial-A104IC2U', 9600)
ack='A'

while True:
incoming = ser.readline().strip()
if incoming != 'A':
print '%s' % incoming
ser.write('%s\n' % ack)

On the TI side, I have below code

int incomingByte = 0;

void setup()
{
Serial3.begin(9600); //UART3 has XBee connection
pinMode(LED, OUTPUT); 
}

void loop()
{
Serial3.println("Sending command to the XBee");
delay(1000);
Serial3.println("I am R1");
delay(1000);

if (Serial3.available() > 0) {
// read the incoming byte from UART3
incomingByte = Serial3.read();

// say what you got, print at the usb serial console
Serial.print("I received: "); 
Serial.println(incomingByte, DEC);

}

}

When I run this, XBee communication stops after printing "I am R1" in the python console. I am sure Serial3.available() > 0 is working as when I replace it with a blink code like below, it works and XBee communication keeps working on.

if (Serial3.available() > 0) {

digitalWrite(LED, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}

So looks like the problem is in

 

incomingByte = Serial3.read();

 

From python, I am sending a string (%s) with ser.write('%s\n' % ack). Is Serial3.read() the right read mechanism for the ack string? Anything else?

 

FYI: I tested the serial.read() only with TI (no python involved) by writing something in the console and serial.read() can read and print it.