To make 443MHz RF module work with ADuC832

scchu

There are two ADuC832 and connected with its UART (0V and 5V voltage for high and low) and use hardwire to communicate at 9600 baud in·good condition. I got a pair of 443MHz RF module (#27980 and #27981) to supersede hardwire connection as shown in the diagram. But the communication failed.·I would like to know what is the voltage level of the data pin of both #27980 and #27981? Is a MAX232 required to convert the voltage level for the RF module?··

Mike Green

I assume you're trying to communicate in only one direction (which is all you can do with a single receiver and a single transmitter).

You don't need a MAX232. The RF modules have logic level inputs and outputs (0-5V).

Did you notice the comments in the documentation about using a sync pulse at the start of a transmission?

Is your data inverted (idle at logic 0) or non-inverted (idle at logic 1)? Either can be made to work, but it helps to know which.

You can't just substitute this kind of RF link for a wired link and expect any kind of reliability. You need some kind of error checking
and you may need some kind of initial "sync" character with every burst of information. If you want the wireless link to do all the work
to provide a reliable and transparent serial channel, you should use ZigBee (like xBee) or Bluetooth. You can preconfigure these using a PC
so you can have a "drop-in" bidirectional serial channel.

Post Edited (Mike Green) : 6/15/2007 2:55:05 PM GMT

scchu

Thank you for your comment. You are correct this is single direction communication.

Now the communication is fine and the problem was the wrong connection of TX instead of RX at transmit unit and RX instead of TX at receive unit. After swap the TX and RX wire, everything is OK.

·