HP97 The journey begins

[PANAMATIK]

(06-13-2021 07:31 AM)teenix Wrote:  I'm still toying around with the 97 PIK chip but it still manages to offer some confusion while trying to figure out the intricacies of the print head speed control.

I didn't even try to find out/imitate the exact same speed regulation inside the original PIK chip. There could be a hidden PI regulation involved, which is normally used for speed control. I remember that I used the HCTL1100 chip from HP for motor control in the 80s, HP offered sophisticated motor regulation chips.

Therefore my approach is different and very simple. I sample the Feedback VM signal as often as possible asynchronously to the PWM cycle, and build the mean value. Then it is easy to drive the motor faster when the mean value is too low, and slower if the mean value is too high. It gives quite a fair result as you can see in this video Motor Video (16s 5.5MB)

Bernhard