JY-MCU Pro Mini (made in china)

Some time ago I bought a dirt cheap Arduino Pro Mini clone from dx.com just to see if it worked. I didn’t use it until today, but it works pretty well. It has one major drawback - it uses a non standard FTDI-connector in that it does not use the CTS-pin. It took a little time to figure out how to map this, so above is an image (click to enlarge) of the cable I made and below is the table of the pin mappings:

Adafruit FTDI Friend pin	JY-MCU pin
GND	GND
CTS	-
VCC	VBUS
TX	RX
RX	TX
RTS	DTR

I have a Sparkfun FTDI adapter as well and this one is marked DTR instead of RTS, but it’s otherwise similar. One thing to note - while the board itself is 3.3V there is no problem to use a 5V FTDI programmer with it. The board itself can run on anything from 3.3V to 12V so it’s quite a flexible board. Earlier you could access the website of the makers of this board to access technical documentation, but now it’s gone (or hard to find).

Now - about the ethics of buying china-made Arduino’s. I feel that I can’t post this without discussing it with myself a bit. I really don’t like buying stuff like this from China and the reasons are:

• You don’t get any support if something fails
• Documentation is non-existant
• Nothing is given back to the Arduino project (like Adafruit and Sparkfun does)
• I really should buy locally and not from Asia if possible

Buying this board was just a test, but would I buy more of these? Yes and it really comes down to price and how Open Hardware works. I recently delivered the first part of my first commercial project based on Arduino and electronics. For this project, I’ll need to make something like 50 similar units that respond to a sensor.

The prototypes were based on Arduino Uno’s and if I buy these locally I’ll pay $43 per microcontroller. The Uno’s are rather big so I’ll certainly use something smaller for the production phase. If I do the project based on Arduino Pro Mini’s, I’ll pay $26 per MCU if bought here in Norway. I could also buy them direct from Sparkfun and with shipping, VAT and customs handling they’d be $22 apiece. Not shabby.

However, for such projects I wouldn’t use off-the-shelf solutions. It’s better to make custom boards specifically for the purpose and these would be something like $10 for the PCB and components - not including the soldering. I’ve done this several times now for personal projects, using only through-hole parts and soldering them by hand. In other words - a project like this wouldn’t really be of any benefit to the Arduino project anyway, because it would simply not be the right way to solve such a project.

I really love working with through-hole and DIL parts, but of course SMD is even cheaper than that. Here’s the crux - with the low price, free shipping and how the customs limit in Norway works, I can get the chinese clone-boards for less than $9 apiece. I can’t even buy the SMD parts for that price, let alone solder them. Maybe the answer to this project would be to make a custom board with Arduino Pro Mini header-inserts?

Update: I’m not entirely sure, but I think this may be the website of JY-MCU? It is crazy slow so it’s definitely a chinese website… If you just wait 5-10 minutes, you’ll actually find what I made above at the bottom of this page.