Fan tachometer?

[thisiscam]

Is the "fan0 tach" pin in the schematics actually connected to anything?

[Interfredzo]

No. I also have a tach for the hotend. which I would highly recommend: https://ellis3dp.com/Print-Tuning-Guide/articles/useful_macros/hotend_fan_monitoring.html Had one fan failing and luckily I was near by.

You could use one of the IO connectors I guess. I will try it and leave a comment.

[thisiscam]

I'm confused. If it's not connected to anything, how do you plan to use that pin? Are you suggesting soldering a wire onto the STM chip leg?

[Interfredzo]

You can try soldering directly to the STM chip leg. I wouldn't recommend this unless your SMD soldering skills are very good. I would suggest using PB.6 PB.11 or PB.7 wich are on IN.O, IO.1 and , IO.2.. The tach signal connects the pull up to ground so the supply voltage of the van schould be irrelevant. So just connecting the ground and power of the fan to fan.0 or fan.1 and connecting the tachometer pin from the fan to the signal pin of IN.O, IO.1 and , IO.2 should work.

I guess the config should look like this. For Fan1 and signal to BP11 on IO.1

[fan_generic sb_can_fan1]
pin: sb_can_th:PA3
tachometer_pin: sb_can_th:^PB11

I didn't tried it yet and im no electronics engineer ;-) So no 100% guarantee.

[Interfredzo]

OK I tested it with a Sunon 5V MF40100V1-1000U-G99 connected to IO.2: Power to 5V and Singal to PB7 to FAN1 only ground to PA.3

[fan_generic testfan]
pin: sb_can_th:PA3
tachometer_pin: sb_can_th:PB7
max_power: 1
cycle_time: 0.1
shutdown_speed: 0.0
kick_start_time: 0.5
off_below: 0.20

Since PB7 has a 10k pull-up already I didnt change it. Works flawless.

btw:. Jumper design of JP1 and JP2 is a mess. I'm not sure where the copper traces lead but i tried to disconnect fan1 from 24V and it din't realy worked (glad i tried with the dead board) @eliwong please use a 0 ohm resistor for selection or even better a normal jumper with pins if there is going to be an update.