UART Expansion Card

I have developed a USB to UART expansion card that I have made a fully functioning prototype, this prototype uses the CH340C, along with switchable voltage and logic levels. (3V3 and 5V) This means that I will be starting sales relatively soon, I am estimating to sell these for around 25-30USD plus tax and shipping. Could people reply to this thread to say that they are interested so that I can start fabrication of my first batch. One question for everyone, would they prefer having pins or sockets on the external pins? I prefer sockets due to shorting and debris.


Is this just the PCB or will it have an enclosure? I’d be happy with sockets.

This will be a fully assembled module, I’m hoping to also have a lid but it may be too hard. It does slightly extend from the chassis to prevent using SMD headers and stay with through-hole headers due to stability issues. I will post an image of it inside a enclosure, except I do not have the needed screws at the moment wbich I have ordered as well as the jumpers for the voltage selector.


Assembly has started on 25 units, should for sale within 2 or so weeks, people who contribute to me on patreon will get a discount and early purchasing access, patreon link is in my GitHub, GitHub username is jyancat. Will be for sale for 20USD plus tax and shipping.

absolutely. Let me know when you are done. wotipka at gmail dot com

Now going to be 12-15USD plus tax and shipping. I’m waiting for all my patreons who wish to buy one at a discount get them and then I will begin public sale.


Would you mind sharing what kind of connectors those are on the left side? They might fit my current project pretty well.

They are just jumpers that fit into a standard 2.54mm header.

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The UART Expansion Card is for sale! UART Expansion Card by i2c Labs If you want to use PayPal contact me directly and I am able to manually do it.


I am not familiar with UART - Universal asynchronous receiver-transmitter - Wikipedia. Which purposes or use cases do people use it for?

The used maker market site looks nice!

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@Josh_Cook So cool!


Sorry for not getting back to you earlier, UART is used with heaps of different microcontrollers, for example smaller Arduinos have a UART interface to use instead of having a UART to USB bridge chip. Lots of other devices have debug pins which are also UART. Quite universal standard.

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Just received my UART Expansion Card from Josh and it is fantastic!

I was impressed at the packaging and professional feel it arrived in, and it is working great! I just was trying to figure out how to get a second UART set up for monitoring, and this worked great right out of the box.

Thanks for the explanation! Arduino: Arduino - Wikipedia? What is the “debug pins”?? Sorry, I am quite a beginner in this area.

This looks like a good card to have and I’m happy to see people making use of the open platform. My Arduino Uno gets power and serial communication through USB. It looks like even the smaller Nano has USB as well. Are there smaller or lower power controllers (maybe for IoT) that don’t have a USB interface?