You may supply the motor and the pic from same supply ( if motor need
+5V ) but you must take care about connections. Physically you need to
conect the motor closer to the power supply and  after that the
pic chip. Also a great value capacitor (470-1000uF) must be connected near
motor on supply wires. It's better if a driver/isolator chip is included
between pic and fet transistors.

BUT AGAIN: Why chopped pyrometer ?

Vasile


On Wed, 7 Feb 2001, Graham North wrote:

> Hi, if you read my last post you will know that I am
> controlling a motor in a pyrometer.
>
> Well I have achieved a PWM output, but am having a few
> problems.
>
> I think the motor is 'sending' (right word?!) some noise
> to the PIC, I have it running from a seperate supply, but
> have had to tie the two grounds together because the FET
> needs the source to be zero volts.  I have a diode connected
> accross the motor, and decoupling caps everywhere! What
> else can I do?
>
> I have also written a piece of code that increases the
> duty cycle with a switch press connected to PORTA,0 but
> this does not work. I think it is switch bounce causing
> this. Is there a way to debounce a switch in S/W? Or is
> my code rubbish?
>
> Main
>         call    InitPorts
>         call    InitPWM
>
> Loop
>         btfsc   PORTA,0         ; If switch is not pressed
>         goto    Loop            ; don't worry
>
>         movlw   B'00000001'
>         addwf   CCPR1L
>
>         goto Loop
>
> This code does not take into account the CP1CON,5 and
> CCP1CON,4 bits. Is there a way to increase the duty cycle
> in this way, including these bits?
>
> Well thats enough questions now, I hope someone can give
> me some answers.
>
> Thanks for your help,
>
> Graham North
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