a newb question----i have some atmega644pa-au chips-datasheet states: Speed Grades̶ 0 - 4MHz @ 1.8 - 5.5V̶ 0 - 10MHz @ 2.7 - 5.5V̶ 0 - 20MHz @ 4.5 - 5.5Vdoes that mean that there are only the 3 speeds for external or is it possible to use a 16MHz???
I use 3.3v with 16mhz resonator on a 328p.
So to use 16mhz crystal you need Vcc to be higher than 2.7v I use 3.3v with 16mhz resonator on a 328p.Chuck.
Have you ever had a problem over clocking it like that?
Is there a reason you use the resonator instead of a crystal?
I use thesehttp://www.dipmicro.com/store/XC7-16000less than a quarter each,and two of these, less than 7 cents each,http://www.dipmicro.com/store/C1K22-50No problems. Stock up, you'll use them in all your projects.
nope.Here is the DigiKey partnumber 490-1198-1-ND 16mhz resonator. I connect a 1M resistor in parallel. I have not had any problems.chuck.
Hard to manufacture a small 16Mhz xtal that are cheap...I prefer the stability of a crystal over a resonator.
why the resistor in parallel?
The feedback resistor increases the probability that the resonator starts oscillating.
The Uno R3 has this resistor. But what is the probability that it will fail to start oscillating without the 1M resistor?By the same token overclocking a little increases the probability of the processor failing. But apparently not by much.