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Topic: Pro-Mini Pin configuration (physical placement) (Read 1 time) previous topic - next topic


I've just recently completed a pro-mini based motorized draw bar for my small cnc mill.  As part of that design and to make things a bit easier to build, I designed and had manufactured some printed circuit boards for mounting relays, motor drivers and a solenoid but were pro-mini controlled.  I received the boards and built my first prototypes which worked fine.  However, when I re-ordered some pro-mini's to make units for some buddies, the pin configuration was totally different.  The boards I received were from China (flea-bay) and I even re-ordered more which appeared to be the same as my originals but the pin-out for the programming port was different. 
I know this is open based design but is there a standard pin structure (physical placement) used by any one manuracturer?  If I only order from a higher dollar US supplier, will I be assured that it will not change in the future? 
I guess what I need is a bit of guidance on how to design a board and select a mcu that will not change at what seems to be random builds
Please be aware that this is hobby based and I'm not using it for any commercial/industrial application.
Many thanks for any guidance or experience.


Yes, I'd also suggest putting the '328P directly into your design. Don't need much - 328P, crystal, two 22pF caps, four 0.1uF caps, 10K resistor.  I do it all the time, you can see the '328P and parts at the bottom of this card and at the left of the 2nd card. Add a resistor/LED for power on, add another for activity detector ("L"), add ICSP and FTDI header for easy bootloading and serial downloads.

This one includes an on-board FTDI module:

This one  uses an off-board FTDI module for programming:

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


That's definitely an issue with the chinese clone sellers, the product photo doesn't always match the item you receive. If you contact the seller about the issue there's a good chance they'll give you a full refund and let you keep the Pro Minis. If you begin by sending them a standard message instead of opening an "Item not as described" case then they will be more likely to work with you because just opening a case already harms their seller rating even if you don't leave negative feedback so they want to avoid that.

If you want to stick with using the Pro Mini module in your design, I'd buy one from each of the aliexpress sellers with the lower prices and then as soon as you get a good one buy more from that same seller, same listing. The shipping is so slow sometimes that it's possible the product could have changed in the meantime but I think this is less likely, especially with a high volume seller that specializes in this type of product. At less than $2/ea it's not too big of a disaster if you get the wrong ones. It might be worth just stocking up to make sure you have as many as you're going to need.

The programming pins should always follow the standard FTDI breakout pinout order so there's only two possible variations. I have 6 different brands of clone pro minis in my collection and it's 50/50. The other difference is the location of the A4-7 pins. I have 4 different variations of that pinout. I don't have any variations in locations of the other pins. If you buy from Sparkfun, etc. the layout is unlikely to change.

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