Add new bus bitrates: 666k, 83k

[esaulenka]

Hello!

First of all, thanks fr supporting this project.
It looks like your branch is most 'alive'.

I'ld like to add a new bitrates that sometime may be found in the vehicle units: 83.333k (it can be found in Mercedes body units like radio and climatic) and 666.667k (it's a rare, it used in some very specific bootloaders).

I haven't checked the first one, but 666 works fine with the real hardware.

[Nakakiyo092]

Hello,

It looks like your branch is most 'alive'.

Perhaps Elmue/CANable-2.5-firmware-Slcan-and-Candlelight is the most actively maintained slcan firmware for this hardware.
I’ve been focusing on another hardware platform recently, so this code hasn’t been updated for a while.

I'ld like to add a new bitrates that sometime may be found in the vehicle units: 83.333k (it can be found in Mercedes body units like radio and climatic) and 666.667k (it's a rare, it used in some very specific bootloaders).

I knew that some slcan projects support 83.333k, but I didn't know what it was for.
Thank you for sharing that information.

As for your pull request, I understand that it adds 83.333 k for nominal bit rate via S9[CR] and 666.667 k via SA[CR].
My firmware already supports flexible bit‑timing configuration through the s command,
and I prefer to use that mechanism instead.
For example, s780D0202 would configure the bit rate to 83.333k (see wiki for details).

In my opinion, using the flexible s command is preferable to pre-defining every possible bit rate,
especially those that are rarely used.

Regards.

[Nakakiyo092]

The SA option for 666 kbps is harder to accept.
I have never seen any slcan implementation that natively supports this bitrate.
In addition, there is a repository where SA is used for another purpose: "Set the nominal bit rate to 75k"
I’m not convinced it’s worth introducing, considering the confusion it will cause in the protocol.