atmega328pb support

[alxgarza]

Any chance of adding:

• custom clock frequency
• Timer 4 (atmega328pb)

[dbuezas]

I don't own any 328pb boards, so I could add it if you promise to test it :)

Regarding a custom clock frequency, this was asked for already, but it is a bit more work and I don't understand the value of this (particularly b/c it would have no effect in the generated code). If you have a convincing use case I can give it a go soon

[alxgarza]

Glad to test timer 4.

The only value for setting a custom Clock Frequency is to calculate the final timer frequency.

Also, setting the target interrupt frequency would be a nice addition.

[dbuezas]

I'll have to take a look at the datasheet then. I assume it is similar to timer1

[dbuezas]

oh, the 328pb also has a timer3!

[alxgarza]

This is a nice document that shows the differences between ATmega328/P and ATmega328PB
https://www.pololu.com/file/0J1464/Atmel-42559-Differences-between-ATmega328P-and-ATmega328PB_ApplicationNote_AT15007.pdf

[dbuezas]

The doc doesn't have any specifics on the new timers unfortunately.
It does tho talk about a new peripheral: Output Compare Modulator. Which sounds intriguing. I won't add it yet.

In the datasheet there is what looks like an errata. In mode 8, it looks like the timer 3 uses icr1 as top instead of icr3. I'll assume this is a mistake, but let me know if you find it doesn't work as expected:

I didn't find any more differences between timers 3 and 4 and the timer 1 in the 328p.

[dbuezas]

Allright, 328pb added. Let me know if you find any oddities, as it is a direct copy of the 328p but with 2 extra timers adapted from timer1

[dbuezas]

It's deploying and it looks like it may take a couple of minutes for the github action to get a runner.
You can check the state here: https://github.com/dbuezas/arduino-web-timers/actions/runs/5316219388/jobs/9625502793
Once it is deployed, you'll see there is a new chip in the list: atemaga328pb

[alxgarza]

Excellent!

[dbuezas]

@alxgarza, do you have any feedback? I don't have 328pb chips to test this on

[alxgarza]

Not yet. I'm out of the country.

[alxgarza]

As far I can tell, it works properly.