Isaac Marino Bavaresco wrote:
> Em 8/2/2011 22:27, Bob Blick escreveu:
>  =20
>> On Tue, 08 Feb 2011 23:47 +0000, "Wortinguk" wrote:
>>    =20
>>> I have a 16F88 project in need of advise.
>>> PWM output on CCP1 on RB0 drives a MOSFET to drive a motor.
>>> RB0/INT interrupt is enabled (on rising edge)
>>> The interrupt service routine does an adc sample of the current flowing
>>> to
>>> see if there is an overcurrent. (1 ohm resistor in ground side of MOSFE=
T)
>>> This currently drives an LED if an overcurrent.
>>>
>>> But cant get my head around a method to tempory collapse the PWM output
>>> voltage if there is an over current condition and allow the PWM period =
to
>>> continue and re-test the current in the next interrupt. Setting RB0 =3D=
 0
>>> wont
>>> do it.
>>>      =20
>> Hi Dave,
>>
>> A few things come to mind. I don't have the 16F88 datasheet in front of
>> me, so any of these could be wrong. But it is worth checking out:
>>
>> 1.Setting TRIS for the pin that PWM is coming out from. I think TRIS is
>> after the PWM circuitry so this might work.
>> 2.Setting TMR2 to some number higher than PR2 and stopping it.
>> 3.Setting CCPR1H to some number.
>> 4.AND-ing the PWM in hardware with the pin you are driving the LED from.
>> 5.Temporarily turning off PWM in CCP1CON.
>> 6.Setting PR2 to 0? Or does that only work on the next cycle?
>>
>> Cheers,
>>
>> Bob
>>    =20
>
>
> In an old project with PIC16F628, just turning off the CCP1CON left the=20
> pin at the last state set by the PWM controller. Sometimes it stopped at
> "1". To turn it off I needed also explicitly clearing the pin.
>
> Isaac
>
> __________________________________________________
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>  =20

I usually pass a 0x00 duty cycle to the PWM module.
Then turn off Timer2 (or whatever timer is associated with PWM).
And then as a final measure, turn off the output pin.

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