On Mon, 06 Sep 2004 10:43:33 +1200, the renowned Jim Granville
<no.spam@designtools.co.nz> wrote:

>Spehro Pefhany wrote:
>> On Sun, 5 Sep 2004 21:50:40 +0200, the renowned "Meindert Sprang"
>> <mhsprang@NOcustomSPAMware.nl> wrote:
>> 
>> 
>>>"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
>>>news:q4hmj096g7pfq0e1ri9a8g55dfhga4lm71@4ax.com...
>>>
>>>>It would be easier (and cheaper) to use a more modern microcontroller
>>>>with an on-board ADC such as the PIC16F819, which will convert the pot
>>>>rotation into a binary number from 0x000 to 0x3FF, which you can then
>>>>use to calculate the delay time.
>>>
>>>Mmm, it would be much easier and cheaper to use a 555.....
>>>But I guess now it gets off topic...
>>>
>>>Meindert
>> 
>> 
>> Maybe. You can get better initial accuracy and repeatability
>> (including first cycle) and less drift over time/temperature using a
>> microcontroller. The 555/CMOS 555 is ideal for crude timing, short
>> times, or driving a heavy load.  
>
>Since the PIC has a RC oscillator mode, why not simply put the
>variable resistance in there, and change the clock speed ?
>Would do all the OP asked for, and is very like a 555 :)
>-jg

Sounds like it combines the worst features of both. ;-) 

Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Spehro Pefhany wrote:
> On Sun, 5 Sep 2004 21:50:40 +0200, the renowned "Meindert Sprang"
> <mhsprang@NOcustomSPAMware.nl> wrote:
> 
> 
>>"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
>>news:q4hmj096g7pfq0e1ri9a8g55dfhga4lm71@4ax.com...
>>
>>>It would be easier (and cheaper) to use a more modern microcontroller
>>>with an on-board ADC such as the PIC16F819, which will convert the pot
>>>rotation into a binary number from 0x000 to 0x3FF, which you can then
>>>use to calculate the delay time.
>>
>>Mmm, it would be much easier and cheaper to use a 555.....
>>But I guess now it gets off topic...
>>
>>Meindert
> 
> 
> Maybe. You can get better initial accuracy and repeatability
> (including first cycle) and less drift over time/temperature using a
> microcontroller. The 555/CMOS 555 is ideal for crude timing, short
> times, or driving a heavy load.  

Since the PIC has a RC oscillator mode, why not simply put the
variable resistance in there, and change the clock speed ?
Would do all the OP asked for, and is very like a 555 :)
-jg

On Sun, 5 Sep 2004 21:50:40 +0200, the renowned "Meindert Sprang"
<mhsprang@NOcustomSPAMware.nl> wrote:

>"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
>news:q4hmj096g7pfq0e1ri9a8g55dfhga4lm71@4ax.com...
>> It would be easier (and cheaper) to use a more modern microcontroller
>> with an on-board ADC such as the PIC16F819, which will convert the pot
>> rotation into a binary number from 0x000 to 0x3FF, which you can then
>> use to calculate the delay time.
>
>Mmm, it would be much easier and cheaper to use a 555.....
>But I guess now it gets off topic...
>
>Meindert

Maybe. You can get better initial accuracy and repeatability
(including first cycle) and less drift over time/temperature using a
microcontroller. The 555/CMOS 555 is ideal for crude timing, short
times, or driving a heavy load.  

Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

"Jagrolet" <jagrolet@yahoo.com> wrote in message 
news:lsfmj0p1674g1vh45c4ega631uv2ntcrq5@4ax.com...
> Can anyone point me to an example of how the adjust the timing of a
> delay loop +\-  a given time using a potentiometer?
> I am using a PIC16c84 or PIC 16F84 controller.
>
> Example.
>
> Push a button to light an led for 10 seconds after which it turns off.
> (I have figured this out.)
>
> I want to include a potentiometer to adjust this time delay  +\- 5
> seconds.
>
> Any help would be greatly appreciated, as I am new to pics.


You could use another button to cycle through a series of preset delays, 
maybe in 1-second increments? Or do you need "infinite" adjustability? 

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:q4hmj096g7pfq0e1ri9a8g55dfhga4lm71@4ax.com...
> It would be easier (and cheaper) to use a more modern microcontroller
> with an on-board ADC such as the PIC16F819, which will convert the pot
> rotation into a binary number from 0x000 to 0x3FF, which you can then
> use to calculate the delay time.

Mmm, it would be much easier and cheaper to use a 555.....
But I guess now it gets off topic...

Meindert

Jagrolet wrote:
> Can anyone point me to an example of how the adjust the timing of a
> delay loop +\-  a given time using a potentiometer?
> I am using a PIC16c84 or PIC 16F84 controller.
> 
> Example.
> 
> Push a button to light an led for 10 seconds after which it turns off.
> (I have figured this out.)
> 
> I want to include a potentiometer to adjust this time delay  +\- 5
> seconds.
> 
> Any help would be greatly appreciated, as I am new to pics.

Don't know if it can be done on this PIC but the classic way to do 
this was to use a comparator input with the pot connect to it as an RC 
network which charged up the cap from the supply.  How long the cap 
takes to reach the comparator threshold depends on the pot postiton. 
The time gives you a value determined by the pot.

Ian

On Sun, 05 Sep 2004 16:37:21 GMT, the renowned Jagrolet
<jagrolet@yahoo.com> wrote:

>Can anyone point me to an example of how the adjust the timing of a
>delay loop +\-  a given time using a potentiometer?
>I am using a PIC16c84 or PIC 16F84 controller.
>
>Example.
>
>Push a button to light an led for 10 seconds after which it turns off.
>(I have figured this out.)
>
>I want to include a potentiometer to adjust this time delay  +\- 5
>seconds.
>
>Any help would be greatly appreciated, as I am new to pics.

It would be easier (and cheaper) to use a more modern microcontroller
with an on-board ADC such as the PIC16F819, which will convert the pot
rotation into a binary number from 0x000 to 0x3FF, which you can then
use to calculate the delay time. 

Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Can anyone point me to an example of how the adjust the timing of a
delay loop +\-  a given time using a potentiometer?
I am using a PIC16c84 or PIC 16F84 controller.

Example.

Push a button to light an led for 10 seconds after which it turns off.
(I have figured this out.)

I want to include a potentiometer to adjust this time delay  +\- 5
seconds.

Any help would be greatly appreciated, as I am new to pics.