Serial communication needed

NETMF & Gadgeteer
1

Hi guys, I have an easy question: I need to communicate via UART with a 3v3 device, which module do I need to use to communicate with it?
It has only rx, tx and gnd pins (no rts nor cts) and works at 3v3 voltage levels (so a 5v serial isn’t good).
Do I need to use an RS232 module (https://www.ghielectronics.com/catalog/product/355)? Other solutions?

Thanks
Big

2

We need more information on your devices.

Which module do you have?

What is the device you want to talk to?

If both devices are 3.3V then you simply connect TX to RX and RX to TX and then GND to GND and then you have a serial link.

You only need to worry about level shifting if the boards are not the same voltage levels and the one at 3.3V is not 5V tolerant. Converting to RS232 at both would make them level compatible but add additional costs that you may not need. For a one off project is probably acceptable.

3

Thanks for reply!

I need to connect a FEZ Cobra 2 to an ESP8266.
FEZ Cobra 2 works at 3.3v?

4

Yes. It’s based on the G120 SOM.

https://www.ghielectronics.com/downloads/man/G120_and_G120E_Datasheet.pdf

5

So it’s enough to use an extender module and configure pins as Socket U?
Is it correct?

6

Yes, or just connect directly to the expansion header.