Pro Mini type?

[MaxZ]

Hi all,

I have acquired a bundle of second hand Arduino stuff (most of which I will probably never use ), and among that is a Pro Mini board labeled "The Simple". Unfortunately, none of the version descriptions on the back are ticked, so I don't know what version it is, 3V3/5V? 8/16/20MHz? At first I did not see an oscillator crystal, but on closer inspection there is a very small component which looks like a crystal. The only inscription I could detect is something like "A 4", but even with multiple magnifiers I cannot be sure of the 4.
Is there any safe way to test what it is, both Voltage and Frequency? The chip is a Mega 328P.

Cheers,
Max.

Edit: I guess I can just hook up RAW to 7-8V, and measure Vcc to check the voltage.....

[Phil_G]

Hi Max, yes, power it from Vraw and measure Vcc. It will be 5v or 3v3 and from that you can guess it will be 16mhz or 8mhz respectively. Someone (Mike?) posted about the 'simple' but I cant find it now, maybe it was the old forum. IIRC it has fewer I/O pins.

[Mike_K]

Hi Phil

I can't remember if it was me or not! I still have a box full of the Pro Mini Simple and most have the voltage and frequency marked on the back, but they do wear off incredibly easily.

But your suggestion of powering it up by Vraw and testing the Vcc would work just as well. And for confirmation, program it as a 16Mhz board with a 1-second blink (0.5 on 0.5 off) and time the flashes, if it's 8MHz the flashes will be at 2 seconds, the 20MHz (if it exists, I've never seen one for sale) will be slightly quicker than 1 second, 0.8seconds. If you measure 10 flashes and average, you'll be able to tell the difference between 8 seconds 20MHz and 10 seconds 16MHz.

The Simple has all the pins, they're just in difficult positions, A4 and A5 (also used for I2C) are set inside the row of pins and A6/A7 are on the end.

Cheers Mike

[MaxZ]

Thanks guys.

Cheers,
Max.