Distinguishing Clocks.


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?

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.