Interfacing with RX434

I am using the TX434/RX434 combo. One Arduino board is connected to the TX434 and the other to RX434. I have the TX from board 1 connected to the transmitter and sending out data. And the Data out from the RX434 connected to the RX of board 2. The 434s are on a breadboard. The receiver (RX434) receives and I can see the received signal on the scope. However, as soon as I connect the Data out of RX434 to RX of board 2, the line goes high and remains high. Board 2 is a Duemilanove. And I have the USB disconnected from laptop once programming is done.

Not sure what I am doing wrong. Help! :)

I connected the receiver output to a digital pin on the Arduino, the transmitter to a digital output pin on the other Arduino and switched to using the VirtualWire library. This got the two talking.

Seems like there is a problem related to connecting the receiver output directly to the Rx pin on the Arduino. Anyone else faced this?

Anyone else faced this?

Yes, if you use the serial lines for communication on the arduino then the signals can interfere with the signals from the USB / serial bridge. There is a 1K resistor between the signals so if your external input / output is not able to overcome the voltage levels from the USB bridge then it will not work. In general don't use the serial lines if you can help it. Software serial should be used.

Thanks, Mike. I had seen examples of the serial being used with Xbee etc. So, was wondering where the issue was. Your reasoning makes sense.

So... If I understand Mike's post correctly...

Pins D0 and D1 of the Arduino are best used for serial data comms only with the FTDI cable (or equivalent circuitry on your Arduino board, if you chose that route.)

OTHER serial comms should be done via OTHER pins, using the Software Serial library. (This isn't hard, in case you haven't played with it yet.)


a) There's a "special resistor" mixed up somewhere in D0 / D1 circuits. Is that there when the FTDI cable is unplugged, e.g. if using a ModernDevice RBBB (or other Arduino/clone without the USB circuitry onboard?

... in any case...

b) You may well want the "built in" serial channel (the one we use to program the device, etc), even if only during development work, to get informantion via the IDE's "serial monitor" feature.

Thus it is unwise(?) to be using D0 and D1 for other things which will probably clash.


If you want help with using the Software Serial Library, there's a long tutorial at....