Seeeduino: 16MHz is too much for 3.3V

Community User Voice
#1

Hi, I bought a Seeeduino v2.2, and I really like the improvements compared to an Arduino. However, I have a small concern: according to the ATmega328 datasheet, the minimum voltage for 16MHz operation is about 3.8V, and it’s no wonder that other 3.3V Arduino boards run at 8MHz. I have tried it at 3.3V and it seems to run fine, but users might want to look into lowering the frequency when running at 3.3V (by using the CKDIV8 fuse and the CLKPR register to get 8MHz or less).

Other small issues I’ve noticed:

  • the AVR usually resets when you switch from 3.3V to 5V (but not the other way)
  • it also resets when you flip the switch for auto/manual reset
  • in manual reset mode, I haven’t been able to upload a sketch. Is there a procedure to do this?

I also have a suggestion for future versions: put the pin 13 LED behind a voltage follower op amp, so the load won’t interfere with anything. Maybe the other half of the existing LM358 can be used for that?

#2

Hello,
Thanks for your post here.
yes, run 16MHz@3.3v is a bit out of datasheet described, but 16MHz@3.3v really works well.
Please plug off the power before you change the 3.3v/5v work power.
“in manual reset mode, I haven’t been able to upload a sketch. Is there a procedure to do this?”
Yes, the manual reset means: it will not reset while you plug USB/upload the sketch.

“I also have a suggestion for future versions: put the pin 13 LED behind a voltage follower op amp, so the load won’t interfere with anything. Maybe the other half of the existing LM358 can be used for that?”
yes, thanks for your good suggestion, we will add this feature in the next version…

all the best
Albert

#3

can you add the 4th mounting hole as on the uno?