Interfacing 433MHz RF Module with PIC16F688

Thread Starter

Leonard Lim

Joined Oct 8, 2019
I am trying to interface the RF module which comes with Transmitter (FS1000A) and Receiver (MX-RM-5V) in pairs and interfacing with 2 sets of the circuit consists of 2 PIC16F688. After sourcing the internet, it seems like it can be interfaced either digital I/O or UART but I'm not sure about this. Is this possible to connect both of RF module in the following manner:

Transmitter side: Transmitter (FS1000A) - PIC1 (TX) [Not sure about the RX of PIC pin should be floating, grounded, shorted with TX or connect to Vcc (5V) since the transmitter only have 1 data pin]

Receiver side: Receiver (MX-RM-5V) - PIC (RX) [Not sure about the TX of PIC pin should be floating, grounded, shorted with RX or connect to Vcc (5V) since the transmitter have 2 similar data pin]

Sourced Baud rate - 9600

Please give some advice if anything is wrong in my statement and suggest some guidance. Thanks in advance.


Joined May 12, 2020
Yes! Roman Black's page gives really accurate info on this topic. As he said, and contrary to many other opinions, a standard UART signal works well up to 1200 bauds (on most reasonable setups). 9600 doesn't. Rx on transmitter side, grounded or pulled-up. Tx on receiver, left floating.


Joined Jun 5, 2013
I have successfully used these modules with a PIC UART. But, in the end I used software UART because I could be more robust at rejecting spurious signals.

One trick I used was to require a solid mark signal for 10 bit times before trusting the transmitter. When the transmitter is off, the receiver reads high quite randomly, but, it appears that after seeing a strong signal from the transmitter, the receiver reduces its sensitivity. Then, during the space periods, no spurious signals are seen.

I am running at 1000 bps. It still has frequent errors and needs a robust protocol to avoid data errors.