Kerry,
     OK! So do I set it up as an output and change the bit to a low or a=20
high as needed using the PORTC command? My thinking for the pull down=20
was to insure that the bit was low until I wanted it to go high. But do=20
I needed? Can the port truly hold it low?
Thanks,
rich!

On 7/19/2014 9:13 AM, Kerry wrote:
> Won't work.  At least, not the way you think it will.
>
> PICs use a read/modify/write sequence to set/clear output bits. The read
> portion is a read of the actual voltage on the I/O pins, NOT what is in
> the latch.  So, if PIN_A0 is set to output a 1 but is set as an input,
> setting PIN_A3 will cause the PIC to read port A (including the 0 on
> PIN_A0) set bit 3 and output that byte, thus setting the PIN_A0 latch to
> 0 and outputting a 0 when you changed the TRIS.
> You would need to do one of the following:
> 1) Not use any other pin on that port as an output.
> 2) Use a byte of memory to hold the port value and only output that byte
> to the port after modifying it.
> 3) Set PIN_A0 before changing the TRIS each time.
>
> And you would not gain anything.  If it is 0.5mA with a 10K pull down,
> it is 0mA without it.
>
> Kerry
>
> On 7/19/2014 5:32 AM, Richard R. Pope wrote:
>> Hello all,
>>        I just had a thought. Oh, what a dangerous thing. Oh well here it
>> is. What if I pull the output pins low with a 10K resistor hooked up to
>> ground and leave them in input mode. When I want to output a high I then
>> change the pin from input mode to output mode. I have already setup the
>> pin to output a high. So I am only changing the TRIS bit for the pin and
>> since the pins are only high for a very short period of time this would
>> minimize the current draw. This would only be 0.5mA of current. Am I
>> thinking clearly on this? What about using a 100K resistor?
>> Thanks,
>> rich!
>>

--=20
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