Add 1M and 4M data bit rate, change clk to 160MHz

[Sl-Alex]

This PR changes the following:
- Changes system clock from 170 to 160MHz, making it possible to easily calculate high bit rates
- Fixes low bit rates (prescaler must be smaller than 512)
- Implements additional bit rates, such as 1M and 4M
- Implements transceiver delay (very useful, especially for isolated transceivers with the high loopback delay)
- Adds missing confirmation messages in SLCAN protocol

Important
There is a bug in cangaroo SW, that sets the data bit rate to 2M regardless of the user's choice. I already tested the fix, will clean up the code and prepare a PR.

[Elmue]

Hello

It is great that you improved the code.
But Normaldotcom is a dead project.
Nobody is caring about the obvious issues there.
Can you please upload a new binary with your modifications?
Most people who own a CANable (e.g. from MKS Makerbase) will not be able to compile this on their own.
So I would say a bugfix or a new feature is quite useless if there is no compiled binary.

I just posted a new issue on Normaldotcom but I'am sure nobody will ever care, although this can be fixed in 5 minutes.
It would be great if there would be a follow-up project for the dead normaldotocom

[Sl-Alex]

Hi @Elmue,
It's been a while since I implemented this fix, so I would need to retest it (I still have an adapter) and then I'll upload the binary. This might take a while, but at least now I know it will be useful for someone else 😉

[normaldotcom]

Hey guys! Fortunately I'm still alive over here, but I haven't been able to give this project much love in a long time. I don't have any hardware set up to test at the moment and don't like to merge PRs without hardware testing. Since I don't have time to test this, @Sl-Alex if you get around to testing, please post in here and I will merge in your change. Thanks!

[Elmue]

@normaldotcom

Hey guys! Fortunately I'm still alive over here,

That is good news because this project seems to be dead.
Can you do me a favor?

I wrote a completely new Slcan and Candlelight firmware 2.5 which is 100% backward compatible with yours, but adds many new useful features.

Can you add a link in your project description that leads people to the new version ?

I also offer a new Firmware Updater that people without programming skills can use to update their CANable with one click.

I wrote a very detailed description here:
https://netcult.ch/elmue/CANable%20Firmware%20Update