Re: [avr-gcc-list] AVR and PWM

[Brandon Tolbert]

    thanks for the code snippet it really did give me a good idea of what is
going on. the timers are a bit confusing to me but I think it is starting to
make sense. Thanks again

B

----- Original Message -----
From: "Leon Heller" <address@hidden>
To: <address@hidden>; <address@hidden>
Sent: Saturday, June 08, 2002 2:46 PM
Subject: Re: [avr-gcc-list] AVR and PWM


>
>
>
> >From: "Brandon Tolbert" <address@hidden>
> >To: "AVR List" <address@hidden>
> >Subject: [avr-gcc-list] AVR and PWM
> >Date: Sat, 8 Jun 2002 12:18:55 -0500
> >
> >OK guys can someone point me in the right direction to learn about PWM on
> >my avr 2313? I am looking for a bit of code or web page that will explain
> >how this is done. I am thinking about using it for motor control in my
> >microbot. Thanks for any help!!!
>
> Here's a little test program I wrote when I was using PWM with the 2313:
>
>     .include "2313def.inc"
>
>      .def      temp=r16
>
>      .cseg
>
>      ldi       temp,RAMEND    ;initialise stack pointer
>      out       spl,temp
>      ser       temp           ;Port B outputs
>      out       ddrb,temp
>
> ;clear all registers
>
>         clr     temp
>         out     tccr1a,temp
>         out     tccr1b,temp
>         out     tcnt1h,temp
>         out     tcnt1l,temp
>         out     ocr1ah,temp
>         out     ocr1al,temp
>
>
> ;set up PWM output via PB3 (pin 15)
>
>         ldi     temp,0x81       ;non-inverting PWM, 8-bit
>         out     TCCR1A,temp
>         ldi     temp,0x02       ;CK/8
>         out     tccr1b,temp
>
>
>         clr     temp
> loop:
>         out     ocr1al,temp
>         inc     temp
>         rcall   dly
>         rjmp      loop
>
>
> dly:
>      ser       r17
> dly1:
>      ser       r18
> dly2:
>      dec       r18
>      brne      dly2
>      dec       r17
>      brne      dly1
>      ret
>
> If you drive a small bulb (incandescent) via a power transistor from the
PWM
> output you should see it slowly increase then decrease brightness.
>
> Leon
> --
> Leon Heller, G1HSM Tel: +44 1327 359058 Email:address@hidden
> My web page: http://www.geocities.com/leon_heller
> My low-cost Altera Flex design kit: http://www.leonheller.com
>
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at
http://explorer.msn.com/intl.asp.
>

avr-gcc-list at http://avr1.org