BMW CAN databases #1
Description
https://github.com/killinen/BrakeModule#someone-might-think
As you mentioned another way would be to command DSC to the braking. If you have BMW's Dynamic Cruise Control (DCC - S540), then you could control the cruise speed setpoint rather easily via +/- buttons messages. That's what I do. Note, my BMW E82 1-series didn't have a dynamic cruise originally and I needed to code it in. After the coding DSC takes over cruise speed control and requests torque from DME and of course does the braking.
For the normal Cruise option (S540), the speed control was in the DME.
As to ACC option (S541) - I don't know what controls what. Perhaps this is the clue.
Who knows - maybe these CAN databases could be similar to E39 and useful:
https://github.com/HeinrichG-V12/E65_ReverseEngineering
And mine: https://github.com/dzid26/opendbc-BMW-E8x-E9x
Of course, I know hacking the DSC module itself should be the more generic approach (if anyone will dare to reproduce).