Aha!

The for loop doen't have any increment of the loop variable!

Yes, that was a bit unusual. Even if it is by-the-book when it
comes to C standards, I'd also use some other construct, such
as a (more normal) while loop.

Jan-Erik.



Allen Mulvey wrote 2014-07-20 19:16:
> Richard,
>
> I think you are getting there but there are a few details you missed.
>
> I've never seen a for loop used like this but it looks like it should wor=
k.
> I would reset count and use a while loop to wait for the incrementing.
>
> What you missed is that resetting count is only part of the reset. This i=
s
> the 10ths of a second. Meanwhile you don't know where the clock is and wi=
ll
> probably miss part of the first cycle. To get accurate timing you need to
> stop the clock with the enable bit, reset the clock high and low register=
s,
> and reset count. Then use the Clock Enable Bit to accurately restart the
> clock, wait for count to increment, etc.
>
> Putting some of this inside the ISR can be more efficient and even more
> accurate as you may eliminate various call and return functions.
>
> Allen
>
>> -----Original Message-----
>> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of
>> Richard R. Pope
>> Sent: Sunday, July 20, 2014 5:23 AM
>> To: Microcontroller discussion list - Public.
>> Subject: Re: [Pic] Making a special timer!
>>
>> Jan=3DErik,
>>       I think I finally understand. I did this.
>>           Reset display;
>>           Turn the Gate on;
>>             call delay(numberseconds);  //This will be for one second
>>           Turn the Gate off;
>>
>>           call delay(numberseconds); again  /This will be for 15 seconds=
..
>>           do forever
>>
>>           delay(numberseconds)
>>           {
>>               for(count =3D 0; count <=3D numberseconds*10;);
>>               return;
>>           }
>>
>>           interruptcode goes here.
>>
>>           void Interrupt()
>>           {
>>               if (TMR1IF_bit)
>>                   {
>>                        TMR1IF_bit =3D 0;
>>                        TMR1H =3D 0x0B;
>>                        TMR1L =3D 0xDC;
>>                         count++; //This increments the count variable
>> which was declared as global.
>>                   }
>>            }
>>
>> It compiles. Now I have to test it and see what the output is. If this
> works I'll
>> then add the pot and the ADC so that the display time can be varied. I'm
> getting
>> there.
>> Thanks,
>> rich!
>> P.S. Allen this also uses your suggestion.
>> Thanks,
>> rich!
>>
>> On 7/19/2014 4:39 PM, Jan-Erik Soderholm wrote:
>>>    > Jan-Erik,
>>>    > The interrupt happens every 100mS. So for a one second delay I nee=
d
>>>    > to execute ten interrupts.
>>>
>>> No, that is done automaticly. You doesn't have to
>>> do anything, the 10 interrupts will happen each
>>> 1 second by the hardware.
>>>
>>>    > But I just don't understand how to do this.
>>>
>>> You don't have to do anything. Just let your interrupts
>>>
>>
>> --
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>
>
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