I am using the two HPWM channels of a PIC 18F452, one to control a motor and one to control a proportional solenoid. The HPWM motor control is new to the circuit. I have been operating the solenoid from HPWM and it works fine. Having just added the motor to the other channel it seems to affect the solenoid.

The motor speed is to change when a pot is adjusted and the solenoid should only adjust by small amounts in relation to a temperature. However as the pot is adjusted, the solenoid seems to open and shut erratically, and it should remain at a constant position. Both motor and solenoid have suitable flyback diodes installed.

Is there any reason for this? Is it a hardware or software problem. I would be most greatful for any insight into this.

hugh