Distinguishing Clocks.

Hi

i have a bunch of Arduino Pro minis . Some of them are 8mhz and some are 16Mhz. the crystals are WAY too small for me to read anything on them.

How can i tell at what clock is my Arduino running ?

both the 8mhz and 16mhz compiled codes seem to work on all of them :S

oh it seems with the simple blink program and Delay (10 000).
and counting the timebetween blinks i can tell the frequency.
as 8mhz compiled code on a 16Mhz arduino would blink in 5 seconds.
but i would still be intrested to know if there is a way of reading the clock without looking at the crystal :slight_smile:

They didn’t mark the bottom silkscreen like in the official portrait?
http://arduino.cc/en/Main/ArduinoBoardProMini

Maybe you can read the voltage regulator next to the LED. It will be 5V for 16 MHz and 3.3V for 8 MHz.

If that doesn’t work you could apply 5-12V to the RAW voltage input and check the VCC pin voltage.