ATMEGA328P 1.8V 4Mhz

Hello everyone. I was wondering how to program a board wich works with an ATMEGA328p 1.8V at 4MHz, until now I was working on a board with 3.3V 8MHz So I used the Arduino pro mini with 3.3V and 8MHz on Arduino but now I don"t know how to do it with lower voltage and lower frequency. thank you for your time. Have a good day and a good Week end !

Arnaud

Do you have a board which works with 1.8v and 8MHz or you are gonna build it ? Please Elaborate

I was wondering how to program a board wich works with an ATMEGA328p 1.8V at 4MHz

I recently received some boards for LoRA that were m328p chips with 16 mhz ceramic resonator instead of 8MHz.

This thread seems to allow you to run your board at 1MHz,2MHz,4MHZ, and 8MHz. I used a UNO and verified with a scope the clock was working at the different frequencies by setting the fuse for CLKOUT
lead on D8.

Check out Post#2

The way this works is the Uno first boots up initially at 16MHz, so the default bootloader will work properly. And you can do sketch uploads as normal. But then your sketch is compiled at the prescaled clock rate, so when your sketch starts up the first thing is to adjust the clock prescale and then your code should execute at the correct speed. Keep in mind depending on which core you use it may not have the support for some clock speeds.

The 4MHz is no problem, but 1.8V is well below the minimum 2.7V specified in the datasheet for the atmega328P.

In response to reply #2, that technique is useful when wanting to run the code slower without changing the bootloader, but the actual oscillator frequency and operating voltage stay the same. Probably would have problems with lower voltage because the oscillator would be running at an out-of-spec frequency, and you have to be careful of the settings of the brown out detector.

The simplest method is to burn the bootloader using mcuDude’s MiniCore which allows a selection of oscillator frequency. You might get lucky and find a chip that will actually operate at that voltage, but I would not expect high reliability, and if using the internal oscillator the frequency will probably be considerably off spec.

1.8V is well below the minimum 2.7V specified in the datasheet for the atmega328P.

What? Datasheet says 1.8V minimum operating voltage.
Even the "Figure 35-44.ATmega328P: Programming Current vs. V****CC " goes down to 1.8V, and the "Serial Programming" section (28.8) explicitly shows Vcc down to 1.8V. ( DS40002061A, 2018.)

westfw:
What? Datasheet says 1.8V minimum operating voltage.
Even the "Figure 35-44.ATmega328P: Programming Current vs. V****CC " goes down to 1.8V, and the "Serial Programming" section (28.8) explicitly shows Vcc down to 1.8V. ( DS40002061A, 2018.)

I must have been either looking at the wrong data sheet, or at the wrong part in that data sheet, the oscillator speed chart I was looking at dropped off at 2.7V.

Hello everyone, thank you for yours answers ! yes I am building it for now, the board works at 8Mhz 3.3V but I will change the regulator and the oscillator to build a very low power system for Iot purpose !