Those nice magnetic connectors (four pins) were waiting to be used in some small project of mine, until now.

I needed a way to peek in on a UART serial stream, but did not want to add a UI to the project or always have a laptop along for the ride. So I made what is not all that different from those old DEC VT-200 terminal consoles of old (nevermind if you are not nostalgic for those beasts).

With an RP-2040 to listen to the UART and send the text to one of those nice little Monochrome 0.96" 128x64 OLED Graphic Display.

I first used this snap on terminal concept as part of a project that was logging data to an SD card, but really any project that might need to log serial data can also have a snap on terminal added. Wire the UART to a mag connector, in my case I put 5v Power and Ground on either side while the TX and RX pins are in the middle, but there's not really a standard (until now ;) and the RX is optional as it is not used (yet). [Gnd, TX, RX, 5v] 

The code for any project just needs to send serial data out via UART serial.

import busio
uart1 = busio.UART(board.GP8, board.GP9, baudrate=115200)
# then Write out your messages ...
uart1.write(bytes("Hello Terminal\n", "ascii"))

The code for the terminal console monitor gadget (to listen and display) is Circuitpython. Easy with a just a bit work to get the all the previous lines of text to linefeed-up like terminals do (at least it DOES NOT using up endless green-&-white stripe fan-fold paper).

Other than the wiring for the display, all you need to do is get your power and serial from the mag-connector and remember to connect the TX coming from your serial sending project to the RX on the tiny terminal.  

Once you have this tiny terminal working on a project, adding a little code and mag connector to any new project is easy.  Sending Serial Data out on a UART TX pin and providing a little power and ground is all that is needed to light up a very useful, retro and tiny terminal.