Slowing Down RGB PWM Routine

[Tissy]

I have an RGB sequence which works fairly well, but very quickly. Is there a way of slowing down the routine. I have tried altering the PWM duty, but this just causes the LEDs to flicker. Also the Pause command produces the same flickering results.

I would like the transition of clours to be a lot slower.

This is part of a bigger routine, but i would like to get this part right.

Any ideas from anyone?

Many thanks,

Steve



TRISB = 0

Red VAR PORTB.1 ' All LEDs
Green VAR PORTB.2 ' Connected between
Blue VAR PORTB.3 ' RC pins and ground

rbgArray var byte[3] ' holds the rgb values in this case the led is rbg
x var byte
y var byte
adcVar var byte
rbg var byte ' which value we are changing in the rbg array
rainbowVal var byte ' the current value to produce rainbow
Delta var byte ' find the size of each section in the 6stage rainbow
Section var byte ' which section it is in

maxValue con 255 'the maximum input value for generating rainbow

delta = maxValue/6

y = 0

main:
for rainbowval = 0 to 255
gosub rbgrainbow
next
for rainbowval= 255 to 0 step - 1
gosub rbgrainbow
next
goto main


rbgrainbow:
for rbg = 0 to 2
section = ((rainbowval + ((rbg * 2)*delta))/ delta) // 6 ' this gives what section it is in

select case section
case 0
rbgarray[rbg] = (rainbowval // delta)*6 'this is how far it has gone in its section
case 1
rbgarray[rbg] = 255
case 2
rbgarray[rbg] = 255
case 3
rbgarray[rbg] = 255 - ((rainbowval //delta)*6)
case 4
rbgarray[rbg] = 0
case 5
rbgarray[rbg] = 0
case 6 'this one is for pics bad math
rbgarray[rbg] = 0
end select
next

gosub ledpwm

return

ledPWM:
For y = 0 to 2
Select Case y
Case 0
pwm red, rbgarray[y], 1
case 1
pwm blue, rbgarray[y], 1
case 2
pwm green, rbgarray[y], 1
end select
next
return

[Ingvar]

Perhaps you could call your "ledPWM" routine more than once. That should keep the LEDs happy and take longer time.

[Tissy]

OK, i think i know what you mean, but being new, how do i do that in the code i have. Would you mind giving me an example using my code?

I'm guessing it will use a loop where i call that routine, say ten times and then jump to the next sequences etc.

Many thanks.

Steve

[egberttheone]

That is not so hard let me help ya;




main:

for rainbowval = 0 to 255

for a = 1 to 100
gosub rbgrainbow
next a
next rainbowval
for rainbowval= 255 to 0 step - 1
for a = 1 to 100
gosub rbgrainbow
next a
next rainbowval

goto main


of course you have to adjust the value's and you have to create the variable "A" (if your gone use high value's create a word size variable)

Edit: you could also let a timer run in the background that keeps sending the pwm signals and change the value's in the mainloop

[Darrel Taylor]

Hi Tissy,

Since the software PWM command only works while that statement is active. It's going to be difficult to get the LED's to work the way you're wanting.

Take a look at this link
Multiple Slow speed Software PWM (http://www.pbpgroup.com/modules/wfsection/article.php?articleid=12)

This will allow you to have all 3 PWM's running in the background at the same time. Then you can just cycle thru the PWM levels as needed without worrying about the timing.


HTH,
   Darrel

[Ingvar]

Exactly what i meant ......

FOR X = 1 to 10
GOSUB ledpwm
NEXT