I’ve found out that fixing the RPIO.PWM code for the new PiZero (and a B2 and B3) shouldn’t be that hard. From ‘joan’ on the RPi forum and Chris who wrote the RPIO.PWM code, I’ve found out that the right way to access DMA for PWM is via a ‘mailbox’ instead of building a page map, and even better, Chris pointed me at the ServoBlaster code changes it made to swap from the pagemap to the mailbox method. RPIO.PWM is derived from ServoBlaster, and so the upgrade to ServoBlaster is almost a direct fit for the required update to RPIO.PWM.
So once more, I now have the key I can start with. But for now, it’s back to testing the merge of the new LEDDAR code into Phoebe’s HoG code.