Enable speed/temperature multiplexing on same wire

[devicelocksmith]

Enables speed and temperature multiplexing on the same (usually white) wire. Works with 10k NTC thermistor with customizable Beta value. To retrofit into existing motor with speed sensor, connect NTC between black (negative) and white (speed sensor) wire in the motor. On controller side, bridge SS (speed sensor) to MOTOR_TEMPERATURE pins and one lead of 220ohm resistor. Connect the other end of resistor to 3.3v source on the board (1117 voltage regulator or analog reference pin).

Set R_TEMP_PULLUP to combined resistance of built-in pullup and 220ohm resistor - you could measure the resistance between 3.3v point and white wire when it is not connected to motor.

Set NTC_BETA to Beta value of NTC 10k thermistor in the motor.

Set SP_TEMP_MULTIPLEX to ADC threshold for pull-down (speed sensor hall) signal. Good starting point is 200.