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Topic: UNO compatible USB-to-UART? (Read 473 times) previous topic - next topic


Apr 20, 2019, 12:56 am Last Edit: Apr 20, 2019, 12:57 am by CToast
Hi all,
Sorta new to Arduino.

A project I want to start involves flashing an Arduino UNO.

After it's flashed, the UNO will plug into a third party device. Instructions are then sent to the UNO via RX/TX.

The project lists a "USB to UART" adapter as a requirement. Can anyone suggest one that they know would work with the UNO?

There's a bunch of options and I'm not sure what to look for exactly. Ideally, I don't want to have to solder anything, as I'm very shaky and have a hard time soldering.


I don't understand the need for the USB to UART adapter. Could you provide a link to the instructions you're following?


Apr 20, 2019, 02:28 am Last Edit: Apr 20, 2019, 02:30 am by CToast
Sorry, I wasn't very clear in my original post, re-reading. The reason the adapter is needed is because the UNO will be plugged into another device via the UNO's native USB port.
Communication with a PC needs to be done via UART as a result. The UNO is basically a middle man between the device the UNO is plugged into via USB, and the PC sending instructions to the UNO via UART. Hope that makes sense.

The instructions don't really go into detail on using the adapter, almost all of the instructions are on compiling code and using the libraries (I'm more of a programmer than a hardware guy) -- it just mentions that you'll need a USB-to-UART adapter in the pre-reqs and doesn't mention anything of it again.


Apr 20, 2019, 02:50 am Last Edit: Apr 20, 2019, 02:51 am by pert
The only way that would make sense is if the communication with the device needed to be done at a higher baud rate than possible using software serial. I'm lacking the information to know whether that is the case.

Anyway, I'll just answer your question. This is the one I use:
Some people don't like the cheap "FT232" modules because they use counterfeit FT232 chips, but they work great for me.

The CH340 modules are a good alternative, but you need to do some searching to find the ones that are in the most useful form and they are a bit more expensive. The most common and cheap CH340 modules have a very stupid form and you'll probably regret buying one of those (I know I do). DrAzzy sometimes recommends one that looks nice, but I couldn't find it. I did find these, which look decent:

My advice is to make sure the one you buy has the standardized "FTDI header" pinout:
  • DTR or RTS
  • RX
  • TX
  • VCC
  • CTS
  • GND

That will allow you to plug the adapter right in to an Arduino Pro Mini, or many other boards that use this standard pinout. If you get an adapter with a non-standard pinout, you would need to use a mess of jumper wires to adapt it to the standard pinout, and some don't even break out all the signals you need for full functionality! I realize none of that is needed for your Uno, but this USB to TTL UART adapter is a very useful tool, so it's worth getting a good one.

Don't buy one of those with the USB A connector. That would be super annoying!

You'll note that my recommendation has male pins, while one of the CH340 ones I linked to has female pins. In the case of the Pro Mini, they come without an FTDI header soldered, so you could choose whether you want male or female. I have standardized on the adapter having male pins because that's the way my preferred adapters are. I notice the LilyPad and Arduino Ethernet (retired) use male FTDI headers. So I'm not sure which is the best choice there, but I would pick one and try to stick with that convention on all my devices.


Ultimately, the UNO will plug into the game console, where it will be seen as a controller. Then I can simulate inputs from the computer. Hope that makes sense.

Thanks for the links. I was actually looking at the FT232 modules earlier, but was scared away that they advertise they don't use genuine chips. I plan to mostly be in Linux this summer, so I don't think that should be much of an issue anyway, though.

Thanks for all of the links, I'll do a little more digging, but I think I'm leaning towards something similar to your first link -- I have one bookmarked earlier from Amazon. Just wanted to make sure there wasn't any other things I should be on the look out for, and you answered that as well. Thank you! :)


A couple years ago, FTDI released a Windows driver that "bricked" the counterfeit FT232 chips (actually you could fairly easily get them working again). There was a lot of negativity about this so FTDI quickly released a new driver version that didn't brick the counterfeits. So the issue only ever affected Windows users and is no longer a problem even for Windows users. The whole adapter module is sold cheaper than you can buy the genuine FT232 chip by itself. $0.74 USD w/ free shipping is pretty darn cheap. I've been using mine for years so I certainly got my money's worth out of it!


Thanks for the links. I was actually looking at the FT232 modules earlier, but was scared away that they advertise they don't use genuine chips. I plan to mostly be in Linux this summer, so I don't think that should be much of an issue anyway, though.
If using Linux (Mint), none of the USB-serial chips will be a problem; they just work.

On principle - the "cowboy" behaviour described above - I simply would not use any FT-232, real or counterfeit.  It simply is not necessary when there are three excellent alternatives, usually just as cheap.


That CH340 module looks pretty nice. One of the links I posted was actually to one of those. It's quite compact. Those long FTDI modules always seem to exert a disturbing amount of torque on my boards with the USB cable hanging off them. The micro USB jack may be a positive feature to some who don't have a mini USB cable on hand but I have also had problems with breaking the micro USB off boards. I'd also prefer to see an easier method of switching from 5 V to 3.3 V than the solder jumper.

I definitely am for using CH340 over FT232. I've used CH340 a lot with no problems. I just always have a hard time finding good CH340 modules on eBay so I default to my trusty counterfeit FT232. When I bought mine, the CH340 didn't even exist. I think they were a bit more than $0.74 back then too!

There's definitely something to be said for not supporting counterfeiting by avoiding purchasing known counterfeit goods, even when they are of excellent quality. I bought mine pre-FTDI Gate so I didn't know for sure they were counterfeit, but of course I wasn't incredibly shocked when I found that my cheap eBay electronics weren't quite as advertised.

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