I'm trying to connect a fan on the heated bed pins (free for now...)
I changed HEATER_1_PIN and TEMP_1_PIN to -1 and FAN_PIN to 12
Now i can start and stop the fan with the M106 M107 commands
But i'm not able to change the speed with M106 Sx (with x a number between 0 and 255)
With a multimeter i saw that the voltage is 0 (M107) or ~10 V (M106) but it doesn't change using M106 Sx
Thanks for the help!
The heater drivers on Sanguinololu are PWM, so even when set at the minimum the heater output will output a pulse that alternates between 0 and 12v. You'd need an oscilliscope or a low pass filter to watch the output vary.