Yes, just initialize the pin as an output, then set it high or low as=20
needed.  The PIC will hold the at the proper voltage.

Kerry


On 7/19/2014 8:45 AM, Richard R. Pope wrote:
> Kerry,
>       OK! So do I set it up as an output and change the bit to a low or a
> high as needed using the PORTC command? My thinking for the pull down
> was to insure that the bit was low until I wanted it to go high. But do
> 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 the=
n
>>> 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 an=
d
>>> 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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