Configure 4 Pins for PWM Output (Analog Voltage) On Maestro

3ddevil · 2 Oct 2019, 21:36

Hi @dc42
If I want to create 4X Analog voltage controllers leaving Fan0 and Heaters 0+1 alone, we have come up with this list, which seems to max out our native controller access:

Fan 1
Fan 2
Heater 2
Servo (Z Bed Probe)

According to the documentation here, it is possible to turn these outputs into controllable PWM outputs using https://duet3d.dozuki.com/Wiki/Gcode#Section_M42_Switch_I_O_pin is that correct?

The heater needs to be disabled and not referenced by a tool "using M307 H# A-1 C-1 D-1 to make the pin available." Is there any such requirement for the fans/servo?

Finally, if buffered correctly (F=10KHz) and routed into a proper RC buffer can we expect to an analog output from 0-3.3V for Servo and 0-Vin for Heater and 0-Fan Voltage Set? Can you confirm this is possible?

are there any more outputs / alternative pins natively supported by the Maestro or is that all we can do with the chip as currently routed?

3ddevil · 3 Oct 2019, 04:03

So this is solved for the Servo output, it worked exactly as expected. Quite amazing!

dc42 · 3 Oct 2019, 08:10

@3ddevil said in Configure 4 Pins for PWM Output (Analog Voltage) On Maestro:

The heater needs to be disabled and not referenced by a tool "using M307 H# A-1 C-1 D-1 to make the pin available." Is there any such requirement for the fans/servo?

Yes, see https://duet3d.dozuki.com/Wiki/Using_servos_and_controlling_unused_IO_pins.

Finally, if buffered correctly (F=10KHz) and routed into a proper RC buffer can we expect to an analog output from 0-3.3V for Servo and 0-Vin for Heater and 0-Fan Voltage Set? Can you confirm this is possible?

If using a heater or fan output, you would need to add a pullup resistor to +3.3V if you want a 0 to 3.3V output.

are there any more outputs / alternative pins natively supported by the Maestro or is that all we can do with the chip as currently routed?

The available pins on the Maestro are listed at https://duet3d.dozuki.com/Wiki/Using_servos_and_controlling_unused_IO_pins. Only the heater, fan, and Z probe control/servo pins are PWM-capable.