Serial communication between Arduino and Atmega168

Forum 2005-2010 (read only) Hardware Interfacing
1

I'm trying to use some RF transmitters/receivers, with an Arduino transmitting and an Atmega168 receiving. I tried setting it up and the receiver didn't receive anything, so I tried to simplify it with the Arduino directly communicating via a wired serial connection to the Atmega. Still, there is no serial input. Here is my setup:

Arduino, with the following program:

byte counter;

void setup () {
    Serial.begin (4800);
    counter = 0;
}

void loop () {
    Serial.print (counter);
    counter++;
    delay (10);
}

The code on the Atmega simply reads an incoming byte from the serial and prints it out again. It prints it through a Max2323 IC, which is connected to my computer. I know that the code on the Atmega works, because I can type in the terminal on the computer and the Atmega repeats what I'm typing.

I have the a wire going from the TX pin (digital 1) on the Arduino to the RX pin on the Atmega, but when I power up the Arduino the Atmega doesn't get any input. I've tried reversing it - Atmega printing out, Arduino receiving and printing via serial, but the Arduino didn't have any input either.

Does anyone know what the problem might be? Are there any guides for communicating between an Arduino and Atmega via serial?

Thanks very much!

2

Do you have a common ground between the Arduino and the Atmega168?

3

Ah shoot nope. Do I just put a wire between the GND pin on the Arduino to the ground pins on the Atmega?

4

Ah shoot nope. Do I just put a wire between the GND pin on the Arduino to the ground pins on the Atmega?

Yep.

5

Thanks! I got a wired serial connection between the Arduino and Atmega. I haven't been able to get the wireless working, though :-/

6

What are you using, xbees?

There are many threads on xbee and other wireless issues. Search around a bit and if you then don't find anything, ask the question.

Mowcius

7

Just plain RF modules, like these: Hobby Robotics » Cheap Arduino Wireless Communications. I'm going to try what they say to do here, although I'm not expecting much. He finally solved the problem by getting new RF modules, these are already my second pair so I can't imagine they wouldn't be working.

The voltage to both of them is 4.96 V. If I connect the data pins from the receiver to the transmitter then communication works, but when I remove the connecting wire I don't get any input on the Arduino serial monitor. So I think everything leading up to the RF modules must be working, right?

The receiver/transmitter both have a 17 cm wire antenna, and they're about 10 feet apart. If I hook up an LED to the data pins of the receiver and transmitter, the LED stays solidly on. I'm not sure what that signifies though? Also, the same LED is much brighter when on the transmitter data pin than when on the receiver pin. Again, not sure if that signifies anything but if I had to guess I'd say the receiver is receiving something, but it's not actual data?

I've tried using VirtualWire, as apparently plain Serial.read can have trouble with RF modules. I did everything shown here, but unfortunately still no input from the receiver.

I have now also tried using the "poor man's" software oscillator and I think the receiver is working, and just getting static - there was a constant wave. Still, the Arduino is unable to read anything in.