AVR-Chat

I am using timer 0 for a clock tick.

I am trying to use timer1 for a 2 khz PWM signal generated by the  
internal hardware.

I am trying to use timer2 for a 10 khz PWM signal generated by the  
internal hardware.

I realized the timer tick has nothing to do with the PWM, I just  
copied here because its one of the timers I'm using.


On Nov 30, 2007, at 3:25 PM, Jim Wagner wrote:

> On Fri, 30 Nov 2007 22:42:04 -0000
>  "Rick" <bit.tricks@gmail.com> wrote:
>> --- In AVR-Chat@yahoogroups.com, "Philippe Habib"
>> <phabib@...> wrote:
>>>
>>> Thanks for the reply.  I looked through the data sheet
>> for guidance
>> about
>>> the various counters but I wasn't able to figure out
>> what I need.  Maybe
>>> someone here can help.
>>>
>>> I am using an ATMega 128 clocked at 16 mhz.  What I'm
>> trying to get is a
>>> 10khz PWM from timer 1 and a 2 khz pwm from timer2.  I
>> am using the
>> Bascom
>>> BASIC.
>>>
>>> I expect that what I need to do is to use these like I
>> use timer0 to
>> set up
>>> my 10ms timer tick. For that, I set the prescale to
>> 1024 and by
>> reloading
>>> the timer to 99 each time my timer ISR executes, I get
>> a 10ms tick.
>>>
>>> Since this is a PWM and I don't have an ISR, I'm
>> looking for the way
>> to set
>>> that reload value one time when I configure the PWM.
>>  That's what
>> I've been
>>> unable to find.
>>>
>>> I have experimented with trying to set various timer
>> related things but
>>> haven't gotten it to work.
>>>
>>> Here are my declarations:
>>>
>>> Config Timer0 = Timer , Prescale = 1024
>>> Config Timer1 = Pwm , Pwm = 10 , Compare A Pwm = Clear
>> Up , Prescale = 1
>>> Config Timer2 = Pwm , Pwm = On , Compare Pwm = Clear Up
>> , Prescale = 8
>>>
>>>
>>> I'd appreciate any help from someone who knows the
>> answer on this one.
>>>
>>> Thanks.
>>>
>>
>> Philippe:
>>
> I think there is more than a little confusion here.
>
> When you say "PWM", are you talking abou a PWM signal that
> is generted by internal hardware? Or, are you talking about
> a software PWM.
>
> This quesion arises because you say that you are using the
> timer to generate "10ms tics" and you also talk abou a
> 10KHz PWM.
>
> Normally, the PWM frequency is the repetition frequency of
> the entire PWM waveform. Otherwise, one would talk about
> "PWM clock". Yet, I think of "ticks" as the clock applied
> as the input of a PWM. So, if the PWM is generating
> "ticks", I would think of those as clocks to a software
> PWM.
>
> Further, a 10MHz clock and 1024 prescale will give that
> counter a clock of 9.765... KHz. There is no way that you
> could get a 10KHz PWM out of that setup.
>
> Thus, we need to make sure what it is that you are talking
> about.
>
> Jim Wagner
> Oregon Research Electronics
> Tangent, OR, USA
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