Probably a dumb question, sure hope so. Can a normal through-hole crystal which works great on a 5V project generally be used for a 3.3V project or is there a special requirement? I bought my crystals on the cheap and I don't have a datasheet.
Thank you for any information.
If you are talking about an atmega328p then the maximum supported clock speed @ 3.3V is 13.33MHz. In practice, you may get away with using a 16MHz crystal. The crystal itself doesn't care whether you run the microcontroller from 5V or 3.3V.
dc42:
If you are talking about an atmega328p then the maximum supported clock speed @ 3.3V is 13.33MHz. In practice, you may get away with using a 16MHz crystal. The crystal itself doesn't care whether you run the microcontroller from 5V or 3.3V.
Thanks. I have some slower crystals - 12Mhz and 8Mhz so I guess I will use those to be safe. Speed is not super important, the sketch has delays in it already. The MPU I want to use is a 328P-AU (TQFP).
8MHz will be easier as you won't have to compile a new bootloader, there are pre-compiled ones for 16 and 8MHz, but not 12 AFAIK
MarkT:
8MHz will be easier as you won't have to compile a new bootloader, there are pre-compiled ones for 16 and 8MHz, but not 12 AFAIK
I am planning on using my AVRISP2 and programming the chip directly without a bootloader. I don't think that will be an issue using this route.
If you don't mind running at 8 MHz use the internal oscillator and then you don't need a crystal at all.
I just got around to building this and when I switched it from the internal oscillator to the 16Mhz crystal it bricked the 328P-AU. I forgot about the details on this message so I desoldered that chip and put another one in and left it on the internal oscillator. I guess I can solder the bricked chip onto one of the other boards and try it with a slower crystal. Bad luck I guess. DOH.