Non-pwm cooling fan control

[piranha32]

Hi,

I would like to use for part cooling a mains powered air pump. It needs a phase angle controller to control the air flow, so I can't use the PWM signal from Duet board directly. I can convert it to a DC-ish voltage, however it would be much easier if the board could talk to the pump controller via some kind of serial protocol.
I'm using Duet2 WiFi board. Is there a way to tell the firmware to send the fan speed information in a digital format (via UART, SPI, I2C, or any other digital bus)?

[o_lampe]

@piranha32
It's probably easier to use a small interface-PCB (eg. with ATTiny chip or RP2040) It would measure the duty cycle from Duet2-PWM and translate it to UART signals or other protocol.

[piranha32]

@o_lampe That's one of possibilities, however my goal is not to have the information in a digital format, but to control the pump. It is easier to just integrate the PWM signal and use micro's built-in ADC, and should be precise enough. Having this information in digital format would make make implementation simpler, and I hoped there was a configuration option which enables it.

[dc42]

@piranha32 the standard RepRapFirmware for Duet 2 does not provide that facility. RRF for Duet 3 allows for CAN-FD connected devices to control fans; although CAN may be a rather expensive option for controlling a single fan.

Do you already have a phase angle controller with a digital interface, or are you planning to build one?

[piranha32]

@dc42 Thanks for response. I have a Duet2 board, so CAN is not an option. I'm planning to build the pump controller, and I'm looking around what interfacing options are available.

[T3P3Tony]

@piranha32 said in Non-pwm cooling fan control:

I'm planning to build the pump controller

if thats the case then it would be the least effort to build one that accepted PWM signal duty cycle to indicate requested speed.