BTT EBB 2209 + 3 Wire Fan

[Sandman50]

I have a BTT EBB 2209. Intention is to use a 3 wire hotend cooling fan with the tachometer feedback to shutdown the hotend if the fan fails.

Just getting it all up and running now. I finished the mechanical and wiring yesterday.

The cooling fan is wired into the PWM output on the EBB. PWM isn't used as this is a 3 wire fan and I don't need to control that fans speed anyway.

Problem: The fan is running all the time.

The fan is reporting RPM, so that is good.

relevant config section:

[heater_fan hotend_fan] # Hot End Fan # Fan PWM # max_power: 1.0 # kick_start_time: 0.5 pin: !EBBCan: PB14 tachometer_pin: ^EBBCan: PB15 tachometer_ppr: 2 heater: extruder heater_temp: 40.0 fan_speed: 1.0

Fan reports ~8700 rpm which is about correct for the fan. (8500 on the spec sheet)

https://media.digikey.com/pdf/Data%20Sheets/Sunon%20PDFs/MF40101VX-1000U-G99.pdf

 

[kubik]

Have you tried not negating the pin? The stock config from BTT has it non-negated

#[heater_fan 4W_FAN0]
#pin: EBBCan: PB14
#tachometer_pin: EBBCan: PB15
#tachometer_ppr: 1

 

[Sandman50]

Have you tried not negating the pin? The stock config from BTT has it non-negated

#[heater_fan 4W_FAN0]
#pin: EBBCan: PB14
#tachometer_pin: EBBCan: PB15
#tachometer_ppr: 1

I tried that.

What I've learned is that 4 wire fans have a little bit of logic in them. It appears that the VCC pin for a 4 wire fan is always on. The PWM signal is what changes (sorta obvious in retrospect) to control fan speed.

What I don't know is if the circuit that puts out the PWM signal can handle the current draw from even a small 30mm fan, so I'll likely wire that fan (used to cool the 2209 driver in the head for the extruder) in parallel with the hot end cooling fan. (both 12 VDC). I'll just use the tacho pin for the protection logic on heating the hotend.

 

[kubik]

3-wire and 4-wire fans are different in that 3-wire ones generally have the tachometer output on the third pin, but 4-wire ones have an additional PWM control wire, as you mention in your second message.

I don't understand the second part of your message. You can check how much current can the pins you are using take by taking a look at the schematic and checking what transistors are/aren't used there