Re: Linux x uClinux for ColdFires: what is the best for what?

John Bodnar wrote:
> David Brown wrote:
>> It was pwm timer outputs.  On the MCF5213, you can configure the pwm 
>> outputs as 8 8-bit pwm timers, or 4 16-bit pwm timers (it was a while 
>> ago that I worked on that project, so the details are hazy - and of 
>> course, I could have misread the datasheet at the time).  It turned 
>> out that although you could set up 8 pwm timers, only four were 
>> connected to pins.
> 
> Oh, yeah. The PWM module consists of eight 8-bit channels, pairs of 
> which can be concatenated to get up to four 16-bit channels.
> 
> On the smaller MCF5211/2/3 packages, the four 16-bit channels (1, 3, 5, 
> and 7) are the ones multiplexed with the 16-bit timer channels.  They 
> are also bonded to dedicated pins on the bigger packages (81-ball MAPBGA 
> and 100-pin LQFP).
> 
> The four even-numbered channels (0, 2, 4, and 6) are only available 
> muxed with the 32-bit timer channels.  In retrospect, they could've been 
> muxed elsewhere, but we worked on the premise that most people would 
> want a mix of 16- and 32-bit timers and PWMs, and that the 8-bit only 
> channels were unlikely to be used too often.  You must be using the 
> whole batch of timers and, therefore, had no way to use any of the 
> dedicated 8-bit channels...
> 

In this particular application, I wanted 8 pwm signals but was not too 
bothered about the accuracy - 8 8-bit channels would have done nicely. 
I managed it using one of the bigger packages, using the four available 
pwm channels, and 4 general timers - slightly inelegant considering the 
device had ideal internal hardware, but it worked fine in practice.

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