Atmega328p Chip on lower voltage.

Hello i was seeing that the atmega328p chip can run at 3v i but what also I'm seeing is that need to lower down the clock speed not sure if this needs to be done or not my project almost every part on there is running 3v to 3.3v so what I'm asking will the 328p chip work on 3v with the clock speed it got or needs to be lower and if so how do i lower it down to run on a lower voltage?

on 3.3V or 3.0V you need to use 8Mhz instead of 16Mhz

I’m not sure the minimum working voltage, you’d need to look in the spec, but if you want to operate lower than 3V, you may need an even lower clock rate (if it will work at all)

how can i tell it to go to 8Mhz speed i don't need much speed because I'm just sending a button command to a wireless rf signal so it doesn't require much speed?

ATmega328P's operating voltage is 1.8 - 5.5V. Max. frequency is depending on Vcc (see the datasheet for ATmega328P - 29.3 Speed Grades). Clock speed has to be defined for compilation. If it is Arduino or it is using bootloader you have to change bootloader also, made for lower frequency.

josephchrzempiec: how can i tell it to go to 8Mhz speed i don't need much speed because I'm just sending a button command to a wireless rf signal so it doesn't require much speed?

Set the fuses to use the internal oscillator, which runs at 8 MHz.

As for voltages:

MHz  Volts
 4    1.80
 5    1.95
 6    2.10
 7    2.25
 8    2.40
 9    2.55
10    2.70
11    2.88
12    3.06
13    3.24
14    3.42
15    3.60
16    3.78
17    3.96
18    4.14
19    4.32
20    4.50

hello Nick Gammon thank you but how can i set the fuse i never did that before?

If you have an ICSP programmer you can do it easily enough.

My sketch below also lets you change fuses:

http://www.gammon.com.au/forum/?id=11638