I have a C167CR-LM micocontroller board. Output P2.8 is connectec to a small servo motor by means of a NPN transistor. The problem is that the microcontroller resets when the servo motor is connected (sometimes) The servo motor doesn't keep his position stable. The Powersypply voltage is OK there are no dips. Also the resetcircuit doesn't generate a reset. But when the motor is connected the microcontroller keeps resetting. Can it be that the motor can reset the microcontroller by means of the output pin?
Watchdog reset?
Any pin that is driven out-of-spec may probably reset - or hang - the processor.
Or may you have any interrupt line unconnected, resulting in spurious interrupts?
My the way - does your processor have any register where it tells the reason for the reset?
Many thanks for the quick answers. I don't know about that register, I must figure it out. But anyway as I understand it can be that the microcontroller resets when the servo motor has voltage peaks or to much current on the output pin that resets the microcontroller? Cause of reset on output pin: - voltage peak? (activation watchdog?) - overcurrent? (activation watchdog?)
My powersupply is 5V 3000mA and the servo motor only takes 700mA during rotation. Reset time without motor = 3 seconds Reset time with motor = 5 seconds to 15 minutes (always keeps resetting, stops after 5 sec or 15 min) Disconnecting the servo motor will stop the resetting immediately.