PIC speed problems

[The Master]

I have a theory! I just added some code to the loop (the working part) to change the value of the red LEDs and its started flickering a little. I belive the problem is in the way ive done the PWM.

The PWM counter starts at 255. Everytime TMR0 overflows it decrements that value then compares it with the value of each LED. If they match then it turns the LED on. When it gets to 0 it resets back to 255 and turns off any LEDs whos value is less than 255. I think that by changing the value sometimes the PWM counter "misses" the LEDs value so it never turns on until the PWM counter resets to 255 and comes around to the new value.

When testing DT's code i think he does it the oposite way. Turn the LEDs on and count up then turn them off when the value matches. When testing that code the LEDs seemed to flash brightly rather than turn off for half a second.

Im gonna try and fix that problem but again i wouldnt have thought missing 1 PWM cycle would affect the LEDs that bad

[The Master]

Wow, that was quick. I fixed that little problem and all the flickering seems to have gone away! Ive just been moving those scrollbars as fast as possible and they wont flicker at all now.

Although i have learned quite a lot from this thread and finally been able to link a lot of that stuff in the datasheet (the registers) to something usefull, i get the feeling that i could have solved this in the origional code simply by replacing "=" with "=>" 4 times.

Oh well, its not a problem... just a learning oportunity

[skimask]

Although i have learned quite a lot from this thread and finally been able to link a lot of that stuff in the datasheet (the registers) to something usefull, i get the feeling that i could have solved this in the origional code simply by replacing "=" with "=>" 4 times.

I smell what you're cooking...and if you'll notice, in my code, I go the other direction than you do (i.e. opposite logic) and use a "<" which is practically the opposite of "=>"
Funny how it's sometimes the same...but different...

Show some code...Let the rest of us smell what you cooked (or burned )

[The Master]

Yep, your way looks like the way DT's code did it. You turn everything on then count up and turn each LED off as the counter reaches the PWM value. In my code i turn them all off then count down and turn them on when the counter reaches the PWM value.

I think i probably did it that way because my previous PWM circuits controlled AC lights through a triac. The way you and DT did it would still work and probably be better for AC lights but it needs those other components similar to triacs (cant remember the name) and they are more expensive.

Ive uploaded the file so you can take a look. I know theres lots of bits that seem pointless at the moment. Ive got to addin all the other stuff that i had before.

BTW, that still gets serial data in the main loop. I may still need to buffer it in an interrupt once i have all that extra code back in but for now it works and it doesnt need to buffer all the data that arrives.

Edit: I commented out the bit that resets the serial flag. When i was having trouble i thought maybe that changing PIR1.5 was causing another interrupt or something but it turns out that it works without it. Reading RCREG seems to clear it anyway so is that really needed?

Edit2: Ive uploaded a newer version of the code. I used your buffer idea for sending serial data. Not sure if it works because i dont have the PIC here to test it. All i know is that it compiles properly. I still need to figure out how to set the stored address. That will be a tough one

[T.Jackson]

Your code looks good. You have an appreciation for logic, clarity and organization. I see a good programmer.

Trent Jackson

[The Master]

Thanx, I started with Visual Basic. VB is used for much larger programs than PBP so its more important to write tidy code but i guess its a good habit to keep with any language