I've got some replays on this one now, and the problem is solved. A 100nF cap in parallell with the motor solved all the problems with power glitches and  filtered away most of the noise.

Mvh
Stein


> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Stein Sem-Jacobsen
> Sent: Friday, April 21, 2000 3:43 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: 5C gets resett when driving load
> 
> 
> I've set up an 16F84 to drive a DC motor. In order to do that 
> I've hooked up an 330ohms resistor to the base of an BC368. Its 
> emitter goes directly to ground and the motor is wired with a 
> protection diode to Vcc - 5V. When attaching a LED instead of the 
> motor, it works fine.
> 
> When I drive the otput to high, it seems like the device gets 
> reset. I've noticed a little voltage swing when it turns on. 
> Further I've noticed that the port doesn't go all the way to Vcc, 
> instead of 5V output, I get 3,5V to the resistor. But there isn't 
> any overload of the port either, it can't get that much through a 
> 330oms resistor. I can't figure out why it doesn't work.
> 
> The only thing I can think of is that the port short circuit the 
> Vcc to Gnd... I've tried several µC and I've wired it both on a 
> PCB and with wires.
> 
> I've put up a schematic here. 
> http://home.sol.no/~ssemjaco/images/problem.gif The voltage 
> regulator is set up to output 3V (other resistors than in the 
> schematic), but it acts all the same on 5V (notice: "LF" PIC)
> 
> Regards
> Stein Sem-Jacobsen
> 
>