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luminas
- 2nd September 2008, 03:18
If 3 hardware pwm output needed and we have to choose between a 16F737 ( 3 ccp pwm ) and a 18F2431 ( 6 channel/ 3 pair power control pwm )

Which one is better ? Why ?

BigWumpus
- 2nd September 2008, 22:56
The 18F2431 has a specialiced PWM-modul for motor-control. 3 PWMs can control 6 Output-Pins for high- and low-side.
The PWM can produce normal PWMs or center-justified-PWMs. The frequency of the device can be very high to produce fine PWMs...
The 18F2431 has very fast ADC !

The 18F-devices have a better RAM-organisation.

Darrel Taylor
- 2nd September 2008, 23:06
Which one is better ? Why ?

The POWER CONTROL PWM MODULE can have ... "Up to 14-bit resolution, depending upon the PWM period."

That makes it "better" to me.
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Bruce
- 2nd September 2008, 23:46
What are your requirements for the PWM signal?

Will it be used for motor control or something else?

luminas
- 3rd September 2008, 03:48
Thanks guys :)

I am experimenting with both PICs , both system run well as expected

Beside those hardware specific features, is the CPU utilization lower with power control pwm compared to ccp pwm ?

Is there something like " windows task manager " for PIC to see the CPU load ?


Bruce:
It is a motor control with 20 kHz pwm freq.

Bruce
- 3rd September 2008, 15:01
PWM is hardware based so once it's configured & enabled it doesn't require CPU overhead
to continue. Only when you make changes to duty-cycle or frequency.

For motor control I would definitely prefer the 18F2431 with additional built-in safety
options like fault inputs and dead-band. The 16F737 only has standard CCPx type PWM
outputs. The 2431 would be a lot better choice in my opinion.

luminas
- 4th September 2008, 03:09
Thanks Bruce, I will go with 2431. Have a nice day !