Arduino Pro Mini wrong delay and timer

Hi,

I was programming a countdown timer relay which was perfectly working with a Arduino Uno. I was transferring the whole project to an Arduino Pro mini (Pro Mini atmega328 5V 16M from eBay). I then realized that the timer was running slower then normally. It is as far as I can measure with my stopwatch 2 times slower. So meaning when my countdown is programmed for 1 second it takes 2 seconds until the Arduino counts down.

I was then trying to fix it by my self and thereby I realized it is a general problem. Even the simple "blink" sketch runner at half speed. Does anybody has an explanation what is wrong here. Same code on the Uno works perfect and correct in terms of timing.

Would be great if somebody could give me a hind whats wrong

Regards Volker

Sounds like you got a 8 MHz Promini vs a 16 <Hz Promini.
Can you read any markings on resonator? Or perhaps it is not fused correctly and is running on the internal 8 MHz RC circuit.

Thanks a lot for the hind. It seems to be a 3.3V 8mHz controller. With the new settings everything is working fine.

Best regards Volker