I wish to thank fechter, The7, Tiberius and everyone else for working together to finally solve this PUMA mystery.
Like I said in my very first ES post ... "I am a ChE but I didn't know shit about ebikes until I started reading this forum."viewtopic.php?f=2&t=4109
In my ignorance I recently asked fechter ... "So I am ignorant ... is the "analogue" v "digital" thing an issue of hall signal processing to control firing of the fets?"
fechter took the time to educate me and gave me this great answer ...
"If you upgrade the FETs in the old analog controller it will run much cooler.
The analog controller takes the hall signals and uses analog chips to derive the commutation sequence and the PWM. There are some dedicated brushless motor control chips available today that work like this (MC33035). There is no software, everything is done with hardware, making it extremely fast. The controllers [REDACTED] was getting from the manufacturer were made like this. They had other problems apparently.
The digital controller takes the hall signals and feeds them into a microcontroller unit. The throttle, low voltage signal, current signal, everything, goes into the MCU. The MCU uses software to process all the inputs and generate an output that looks like the analog one. All the adjustments, features, and limits can be done in software.
The "advantage" to the digital controller is the MCU is very cheap and very few other components are needed to make a controller. It's also easy to change the features by changing the software. Typical R/C controllers use this approach and seem to be quite reliable. If done properly, it works well. It is the way of the future.
I think if Keywin could find a faster processor and just substitute it for the one in there, it could go much faster ... The existing processor is clocking at 16 mhz but it is rated for up to 20 mhz (or at least the official Microchip version). It might be possible to increase the clock frequency by changing the ceramic resonator (like a crystal). I'm not sure what happens if you overclock it too much. Going from 15 to 20 mhz might give you enough speed to run the Bafang at 72v.
Let me see if I can find a faster crystal. Those are cheap ... "
So you can see that fechter nailed the problem thru experimentation.
He did this by verifying the code theory as originally offered by The7.
I am lucky to know such a great group of intelligent people (endless-sphere) ... from all over the planet.