Add atmega328p-hal & arduino-uno support

[jonahbron]

Created a new crate for atmega328p, copied the code over and updated the list of GPIO pinouts and updated the specific pins used for USART and TWI.

[Rahix]

Please also port the examples from leonardo and make sure they work. If you need any help, please don't hesitate to ask!

[Rahix]

Just as a heads up: For the leonardo-panic (and thus for the uno-panic example you'll add) to work, you need to use my latest master branch which contains cab8613.

[jonahbron]

Yeeeeeaaaaahhhhhhhhh bbbooiiiiiiiiiiiiiiiiiiii

First try, the blink example works on my Uno. 😄

[jonahbron]

@Rahix The blink, serial, and panic examples have been ported and tested. I don't have any hardware with which to test I2C example however. Are you willing to consider this completed without that example?

[Rahix]

Yeeeeeaaaaahhhhhhhhh bbbooiiiiiiiiiiiiiiiiiiii

First try, the blink example works on my Uno.

Heh, I know that feeling all to well ;) Makes all the hard work worth it!

---

Thank you very much for your port! I have added a few comments, once those are resolved I am happy to merge.

Are you willing to consider this completed without that example?

Please add the i2cdetect example and at least check that it reports an empty bus. I might have access to some ATmega328P based hardware soon, I will test it in detail then.

[jonahbron]

Thanks for the review @Rahix . I'll try to work on those items tonight (Central Standard Time).

[jonahbron]

@Rahix All of your requested changes are complete, and the i2cdetect example has been ported. To confirm, is this the expected serial output?

Write direction test:
-    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:       -- -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Read direction test:
-    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:       -- -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

[Rahix]

Perfect! The i2cdetect detect output also looks like it should. I will try to test it against some actual bus soon, though I don't expect any surprises there.

Thank you very much for your work on this! 😃