I just started the next one I always wanted to do.
An RGB LED color changing using a VR.

PIC is 12F675

Code is already running. I have implemented soft PWM using the method John taught me during the computer table light.

So fay I can control the brightness for all or one color. Mixing is next. My approach is simple. But before that I like to figure out something.

Below is the part I like to know

unsigned int Freq_temp;
unsigned char GPIOimg, Freq;

Freq_temp = ADC_Read(0);
Freq = Freq_temp/10;
PWMduty = Freq;

I am reading the ADC and using it to update the Duty.
I get 64Hz flicker free brightness control.

Q is in here "Freq = Freq_temp/10"
You see the divider "10". If I go to ">100" brightness does not go to max and if low (<4) I get jumping in brightness around some ADC positions . I scoped the output and "10" seems a fine value as I can go from 0 PWM to MAX. How I got it doing trial and programing and checking......

I figures since "Freq" is like 0-255 and the ADC is more. I tried to scale it down thinking that an "int" is like 655535. So I tried divide by 257 to scale it down and brightness was way low.

I am thinking it should be 1023/255 = ~4 . Cause 4 is also working ( I just tried it ).
But wait 4 is also not as good as 10 at high brightness. "10" seems better ( gives smooth brightness change when pot is changed all the way .

So what value is "Freq" ?
Better yet if ADC is 5V max, what is ADC value, is it 1023 or something else ?

{ed}
"20" seems better at low brightness than "10"

Like to figure out the max value in which "Freq" is at max ADC

 

8 bit ADC = 2^8 = 256 discrete levels (0-255)
10 bit ADC = 2^10 = 1024 discrete levels (0-1023)
12 bit ADC = 2^12....
14 bit ADC = 2^14...
etc..

So if you have a 10 bit ADC your readings will be from 0-1023

 

so to scale down to 255, I should use 4 or 5 ?

But I get far better brightness variation if I divide by 30

 

So if use 31...

Freq_temp = ADC_Read(0);
Freq = Freq_temp/31;
PWMduty = Freq;

Does the PWM Duty varies from 0 - 33 ?

 

So if use 31...

Freq_temp = ADC_Read(0);
Freq = Freq_temp/31;
PWMduty = Freq;

Does the PWM Duty varies from 0 - 33 ?

Assuming a 10 bit ADC then yes..
1023/31 = 33

 

I just started the next one I always wanted to do.
An RGB LED color changing using a VR.

PIC is 12F675

Code is already running. I have implemented soft PWM using the method John taught me during the computer table light.

So fay I can control the brightness for all or one color. Mixing is next. My approach is simple. But before that I like to figure out something.

Below is the part I like to know

unsigned int Freq_temp;
unsigned char GPIOimg, Freq;

Freq_temp = ADC_Read(0);
Freq = Freq_temp/10;
PWMduty = Freq;

I am reading the ADC and using it to update the Duty.
I get 64Hz flicker free brightness control.

Q is in here "Freq = Freq_temp/10"
You see the divider "10". If I go to ">100" brightness does not go to max and if low (<4) I get jumping in brightness around some ADC positions . I scoped the output and "10" seems a fine value as I can go from 0 PWM to MAX. How I got it doing trial and programing and checking......

I figures since "Freq" is like 0-255 and the ADC is more. I tried to scale it down thinking that an "int" is like 655535. So I tried divide by 257 to scale it down and brightness was way low.

I am thinking it should be 1023/255 = ~4 . Cause 4 is also working ( I just tried it ).
But wait 4 is also not as good as 10 at high brightness. "10" seems better ( gives smooth brightness change when pot is changed all the way .

So what value is "Freq" ?
Better yet if ADC is 5V max, what is ADC value, is it 1023 or something else ?

{ed}
"20" seems better at low brightness than "10"

Like to figure out the max value in which "Freq" is at max ADC

Do not try to divide an integer and expect a real as answer.

 

So how should I divide the int to vary the duty ?
It is working so far....!

 

So how should I divide the int to vary the duty ?
It is working so far....!

Your PIC has ab A2D capable of either 8 or 10 bits of resolution. You do not state the resolution of your soft PWM.

Unless you disclose your secret numbers no one can answer your query.

 

umm .. That is kinda problem. I trying to figure out my PWM resolution. I not very good at soft PWM yet.
How do I figure out if I am using 8 or 10 bit.

 

What's the maximum value your ADC returns?

If it's 255, it is an 8 bit ADC.
If it's 1023, it is a 10 bit ADC.

 

crap! 12F675 has no ICD. Tried to step thru the code to check that and MikroC said go fish.

I believe I am using 10bit... So how can I found that out with this little bugger ?

 

I cannot see where in the data it says 8 bit ADC for 12F675. It just says 10 bit ADC.

And by the way ADCON0 is set as Right Justified.