PWM generation with PIC16F628

[HankMcSpank]

now I'm no programmer and I might be laying myself bare for everyone to laugh at, but this is how I'd likely approach it...

(disclaimer...there maybe some syntax errors, but you get the methodology blah blah)

begin:

ADCIN 1,pot_sample

if pot_sample = 127 then
fwd_pwm = 0 & rev_pwm = 0
hpwm 1,fwd_pwm,20000
hpwm 2,rev_pwm,20000
goto begin
endif

if pot_sample >127 then
rev_pwm = 0
fwd_pwm =255-pot_sample x 2
hpwm 2,rev_pwm,20000
hpwm 1,fwd_pwm,20000
goto begin
endif


if pot_sample<127 then
fwd_pwm = 0
rev_pwm =127-pot_sample x 2
hpwm 1,fwd_pwm,20000
hpwm 2,rev_pwm,20000
goto begin
endif

pause 20
goto begin

I'm sure to those who really are programmers, then the above is inelegant, but I'm a kludger & therefore go with what I can grasp...not elegancy!

the above assumes 8 bit AtoD which obviously gives 256 levels & therefore a level of 127 becomes your zero point & your duty cycle changes in steps of 2 up to 256 for each direction. But like I say....what do I know?!!!

[mackrackit]

now I'm no programmer and I might be laying myself bare for everyone to laugh at, but this is how I'd likely approach it...

That is my story too... And it does not stop me.

127 exactly might be hard to get with a POT so maybe change the range some.

if (pot_sample >= 122) AND (pot_sample <= 132) then

if pot_sample > 132 then

if pot_sample < 122 then

[Marin]

Thanks for help guys!

This laste if and is important, because of tolerance on POT and so, is better to ahve some more dead time between forward and reverse! Will try this and let you know how it works.

[HankMcSpank]

Thanks for help guys!

This laste if and is important, because of tolerance on POT and so, is better to ahve some more dead time between forward and reverse! Will try this and let you know how it works.

I'd considered a 'dead window' in the middle, but didn't go there as you'd not asked & thought it better to keep it 'pure' so to speak - not sure how/the tolerance of the pot comes into play with respect to you last post - the tolerance refers to how far out the actual resistance is from the specified resistance - you don't really care whether say a 10k pot is 9.8k or 10.2k ...the middle point of your pot will be 127 (unless they've some whacky non linear way of making the pot's carbon track!)...you need the 'dead window' not for tolerance purposes, but to have a better chance of finding/hitting the point on the pot where both sides are at rest.