5

I was looking Arduino Mega's schematic and I noticed a resistor between the MCU and its resonator. R3 in this image:

enter image description here

Why is it there and what is its function?

asked Dec 22, 2016 at 17:29
3
  • forum.arduino.cc/… Commented Dec 22, 2016 at 19:45
  • @Gerben - This addresses R1, not R3. Commented Dec 22, 2016 at 19:58
  • Oops. Didn't even see R3. That's indeed a weird location for a resistor. Commented Dec 22, 2016 at 20:08

1 Answer 1

2

That resistor limits the drive through the crystal. If the power applied to the crystal is too high then the slope and phase shift at the resonant frequency will not be optimal and at really high drive levels could cause mechanical damage to the crystal (like that shattered wine glass trick).

See good instruction PDF here, section 2.1.

answered Dec 27, 2016 at 18:30

Your Answer

Draft saved
Draft discarded

Sign up or log in

Sign up using Google
Sign up using Email and Password

Post as a guest

Required, but never shown

Post as a guest

Required, but never shown

By clicking "Post Your Answer", you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.