Linx RXM-900-HP3 Rf Modules

Hello,

I've been having an intermittent problem with the above mentioned RF units which has caused much hair pulling over the last year.

I have the TX unit being controlled by a PIC16LF873 and the receiving side a 16F877.

The application is for the TX unit to send a single command to the receiver a couple of times a minute, when a button is pushed. I typically push this button 500 to 1000 times per day....Seems like a lot ;)

Once or twice a day the receiver stops responding to the TX unit. Cycling the power to the reciever fixes the condition every time. During this time of receiver non-responsiveness the data ouput from the receiver stays idling at 4.90 vdc (no hashing etc of the data line). The only thing which brings it back to life is the power cycling which makes me think I can rule out RF interference for the most part, unless the interference can cause the receiver to lock up and not respond even when the interference is no longer present.

I have a timeout on the receiver serin code which continues to work while the receiver is not responding.

I'm lost for ideas here for the most part. The receiver channel select bits are solid as is the power down pin and I believe the power supply is clean, which is my first mistake.

One thought I've had is that the RX unit has an internal pullup to Vcc - 300 mv. So the 16F877 Input which is reading the data outout is not being pulled all the way to Vcc (typically 5.1 vdc)

I've switched RX units, PICS, software, PCB layout etc between several designs and see the same issue. So I'm missing something over and over again......I'm sure it's staring me in the face.....


Thanks for any suggestions etc.

Steve

I made a linx remote control ac/dc light dimmer with the LR linx. Used int RCV but also continously sent out the received character for hyper-term type viewing. The RF module idle state always had random noise (due to high gain in module) which showed up on PC as random junk, but the serial on transmission was clear. That way I could always watch tx/rx interaction.
The int rcv is easy to set up.

don