Arduino Mini change from 16MHz external to 8MHz internal oscillator

Using Arduino Microcontrollers
1

Hello,
i have an Arduino Mini (ATMega328p) with a broken 16MHz Xtal and i would like to switch to the internal oscillator.
Is the an easy way or do i have to replace broken 16MHz Xtal first?

zmoho

2

(deleted)

3

Connecting a clock signal to XTAL1 may work (use a series resistor). Lady Ada has a version of ArduinoISP that outputs a reasonable clock. I believe Nick Gammon has a burn bootloader tool that outputs a reasonable clock.

4

Best to replace the crystal/resonator, Much more accurate than the internal RC oscillator. especially with the low price of resonators/crystals. this is mainly because the internal RC clock varies with Both temp and supply voltage. Note that the resonator (worst case) is much more accurate and the crystal (best case) is even more accurate... Than the internal RC clock.. IMNSHO...

Doc

5

According to s. 28.8 of the datasheet, it will work if you provide a clock on XTAL1.
Despite warnings of how bad the internal RC oscillators are, I've found them to be quite good. When testing the serial uart code I wrote with some ATtiny85's, I checked the timing with a logic analyzer. The RC oscillator was within 1%.

6

I Hate to tell anyone to use the internal oscillator although all the Tiny85's I've used were that accurate as well, However when asked about replacing a crystal clock with the RC oscillator... because of a ? Broken Crystal... I generally feel that the person asking the question hasn't supplied enough information or hasn't yet learned the true differences between the two... Btw, I'd Never use the RC clock for anything that didn't live in a temp and voltage controlled environment. The RC clock is OK... from 15 to maybe 30C and with a regulated power source... IT ISN'T good however for everything nor should it be considered really stable. However everyone has their own idea of stable, For many if it works at all, It's good... YMMV

Doc

7

It's working again, i used an old 11Mhz crytal for flashing a new bootloader.
It was a nice test to get more experience and i can reuse the Mini for other tests. It was a pain to see the device laying around and do nothing. :wink:

I fully aggree, the external XTAL make sense for real projects.

zmoho

8