Jaap, this is FilingCab V1.6
PWM frequency was boosted from 490Hz to 20KHz to get rid of hissing noise at low speed
Also the infamous SoftwareSerial library was dropped ]
Serial:
- move pin #11 to RX1 (pin #19)
- move pin #12 to TX1 (pin #18)
PWM:
- move pin #5 to pin #11
- move pin #6 to pin #12
Smoother and quieter control
Happy driving, mind the stair 
FilingCabV16.ino (14 KB)