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Topic: Help IDing this microcontroller (Read 271 times) previous topic - next topic


Have any of you guys seen or bought any of these boards? It's listed as a "Pro Mini atmega328 5V 16M
Replace ATmega128 Arduino Compatible Nano" but its size is the same as the clone Pro Minis I've bought before.

The fact that it says "Replace ATmega128" confuses me, along with the fact that the microcontroller is about half the size of the 328P on all the other clone Pro Minis I've owned.

So what IS this microcontroller? Does anyone know?

I have several of them, and they program and work like the 328P Pro minis. (Before you ask, I can't see the markings on the chip due to tiny size and my cataracts.)



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.


Don't both those chips, the AU and the MU, have similar dimensions, with the exception of the leg configuration? The chip on the bottom Arduino in my pic is about half the size of the one on top.


Apr 17, 2018, 03:55 am Last Edit: Apr 17, 2018, 04:14 am by avr_fred
Don't both those chips, the AU and the MU, have similar dimensions, with the exception of the leg configuration
No, they don't. The standard TQFP package is 6.95mm square, the VQFN leadless is 3.95mm square, not quite half the size. Beware that some of the black boards have the FTDI connection points reversed, you have to flip your adapter over to flash them.

The nice thing about them is they use a real quartz crystal rather than a ceramic resonator so the clock source is more accurate over time and temperature, if that matters to you. The crystal is that big metal can next to the reset switch. In that ancient HC49/U package thru-lead package, it's bigger than the processor. But, hey, they're cheap.

Edit: what the ad should say is "replace ATmega168", the 128 is a typical Chinese typo.


Yes, 7mm vs. 4mm is what the size difference is, thanks! So this is basically the same chip. Not sure why this batch was so much cheaper than the other board but I'm not complaining. Yes, I've already programmed several of them, I bought 20, and I'm used to having to check the pinout for the FTDI and flip it around for different boards.

I don't need the extra precision of the 20MHz Xtal but it's not so bulky as to be an issue so no worries. I use these inside wooden bases for edge lit acrylic signs so the timing isn't critical to drive 8 or 11 WS2812B's.

Thanks everyone for the info!


I have a black board like this in my drawer. It has an ATmega168P soldered to it.
MightyCore -  ATmega1284, mega644, mega324, mega164, mega32, mega16, mega8535

MiniCore - ATmega8, mega48, mega88, mega168, mega328

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