Run 5V A-Star 328PB Micro at 3.3V

Support A-Star and Orangutan
1

Hi. I have the A-Star 328PB Micro 5V and need to power it with batteries at 3.3V. the 328PB can work at voltages between 1.8V to 5.5V according to the datasheet and my other projects. What changes do i need to make to the A-Star 328PB Micro 5V to make it work at 3.3V ?

I have already programmed it through ISP to use the internal 8MHz clock source and set BOD to 1.8V. However, when i power the board with 3.3V through the ISP header, the blue LED lights up but the code doesn’t run. It does work normally at 5V, as expected. It is a basic blink sketch to test with.

I looked at the schematic and from what i could understand, the ISP header is directly connected to the 328PB and should be able to correctly supply the 3.3V, which is in it’s operating voltage range.

What have i missed or misunderstood? The 3.3V version of the board is out of stock at every local shop and can’t really wait for new stock to come in at this time.

2

Hello.

I moved your post to the A-Star support section to keep the forum organized.

We got one of the 5V 16MHz A-Star 328PB Micro boards working with 3.3V using the following fuse settings:

  • extended = 0xF5
  • high = 0xDE
  • low = 0xC2

Can you try those and let us know how it goes? If you still have trouble, could you tell us more about how you are setting the fuses and programming the A-Star?

- Patrick

3

Hi!

I tested the fuse settings you provided and the board works at 3.3V now!

I was using the Arduino IDE with MiniCore to upload the code and I guess that din’t set the right fuses after all. When I set the fuses with avrdude, the board works.

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