pot controlled pwm -- help

[docwisdom]

what pic do you use ?

sample for 16f876:

TRISA = 255 ' Set PORTA als input
ADCON1 = 0
define OSC 8
DEFINE ADC_BITS 8 ' adc = 8 bits

v1 var byte 'Variable v1 holds pot information

high portc.2
pause 100
High portd.2 'power indicator

main:

adcin 0,v1 'Read resistance of pot
pause 10
Hpwm 1, v1, 10000 'hardware pwm on RC2

goto main


End

thanks for this code, but doesnt this base itself on the ADCIN producing a number from 0-255 to feed to the hpwm? I have made these changes and the LED's just stay on, even with adjustment of the pot. I dont think the variable output from the adcin is properly formatted for the hpwm

does anyone know how this is formatted? I cant find any documentation on it.

[docwisdom]

So I gave up on the pot for now and just set a pwm to go to the driver.

hpwm 1, 127, 5000

I get 50% duty with a regular LED, but it doesnt work properly with the LED driver

[sayzer]

Try the attached PWM filter.
Play with the driver resistor and the load resistor to catch a nice signal out.

If you already have a signal amplifier, the NPN transistor may not be necessary.

[Acetronics2]

Hi, Sayzer

PWM is intended to know what you apply to your load, your design is very very very very far from giving a known output ... it's more an ON/OFF output than anything else.

Alain

[milestag]

I don't really care for the HPWM command. I think it's easier to manually set the registers. This is a conversion from part of my code that may work for you to at least get the PWM working.

This is for an 8MHz oscillator (on a 18F2525, so double check register names):

T2CON = 4 'Timer2 = ON; Prescale = 1:1
PR2 = 200 '(period) this should give you should give you about 10KHz
CCPR1L = 100 '(duty cycle) 100 should be close to 50%, 20 is about 10%, etc

To turn PWM ON:
CCP1CON = 12

To turn PWM OFF:
CCP1CON = 0

[sayzer]

Hi Acetronics,

PWM filter is not something I created through my output port; it is what picbasic pro recommends.
If you check the manual or help files, you will find this filter as a solution to scarry pwm out. Still, it is optional.

If you know something else, pls share it with us so that we can learn. Also, PWM is already an on/off state with different intervals on ON mode, on OFF mode etc. and this is called "modulation".

[Acetronics2]

Hi, sayzer

As you're asking, it's a pleasure ...

Just insert a resistor between your Emitter and ground, and the transistor collector current will simply follow linearly ( w. a little offset due to Vbe ...) the PWM value ...
An U/I converter w/ OpAmp could wipe off this offset, if needed ...

No, no, don't send flowers ....

Alain