Second serial port from the 5 GPIO pins?

Has anyone implemented a second serial port (by software) from two of the GPIO pins? I like the Connect ME package but I really need 2 serial ports for my application. I’ve not already purchased the development kit, so maybe I’ll decide going with the Connect-EM instead.

Any suggestion?

Thank you very much,


We did some RS-485 @ 9600bps communications through GPIO and experienced very bad jitter with it, so it did work sometimes and sometimes not. Though the code wasn’t really good, so perhaps good driver (perhaps running as separate thread), could do the trick.

Two serial ports would be nice, but you can’t get everything in nice tiny package :slight_smile: What about multiplexing the port?

Thank you very much for sharing your experiences.

For this development I’ll go with the Digi Connect-EM. It’s already a good solution.


Im also trying to have two serial ports out of development kit, but i found that Real Port Software cannot assign two virtual port to the same port on Digi ME.

I mean I have assigned COM10 and COM20 to the same device, but COM10 seems to be assigned to Port 1 listed on the Device Config Page and COM20 to Port 2…but there is no Port 2 in the Device config Page! I could only connect to COM10 in the tests i did. COM20 Fails due to this problem with Real Port i guess.

Am i right???

I was expecting Real Port Protocol could handle two programs on two different Virtual COMs sending two (COM10 and 20) signals to its TTL Serial Port. After i could try to find a way to have two serial ports on the module out of a software developing effort.

Why not use the Timer 2 to generate the output instead of a thread? This would avoid the jitter…