Hi Steve,
Welcome into the community. Please checkout these links:
Minimal Cortex-R5 example on BBAI-64 - General Discussion - BeagleBoard
BBAI-64 Cortex-R5 gpio toggle experiment - General Discussion - BeagleBoard
CCS Project For C66x/C71x Preloaded Firmware - General Discussion - BeagleBoard
I haven’t worked with DSP cores but, from what Stoerfried posted, it sounds like the IPC is identical to the R5F.
If you get something going for the DSP or even something new going on with the R5F please post back so we can all gain knowledge from your experimentation.