Running atmega 328p on 3.3 v

Other Hardware 3rd Party Boards
3

CrossRoads:
3. What is the best way to program a chip such that it uses 3.3V , with an external clock.

Select ProMini, 3.3 V 8 MHZ for board type, burn bootloader.

@crossroads
I did that, and i found this

  1. the clock got set to 8mhz, i used the blink program to check it (used a 16Mhz crystal, blinking occurred at twice the speed)
  2. the chip still does not work at 3.3V, although it works perfectly at 5V