Configuring PIT for 5-9 Mhz

arunagunasekara — Fri, 21 Sep 2012 13:48:38 GMT

I am using k20 Tower kit and want to generate PWM signal using periodic interrupt timer.In the board am using, CPU is 100Mhz, bus clock of 50 Mhz and PIT of 50 Mhz. Maximum of how much frequency can be generated using PIT and is it possible to generate up to 9 Mhz?I configure one portB pin as GPIO. The PIT triggers the DMA when PIT counter becomes 0 and DMA toggles the GPIO output signal. DMA is requested at the rising edge. When using PIT, DMAMUX source can be always enabled? IF I use always enabled, Will it make any problem when i use other DMA channels for External memory transfer.

Re: Configuring PIT for 5-9 Mhz

apanecatl — Tue, 06 Nov 2012 17:04:42 GMT

Hi arunagunasekaran

1) PIT will always run at 1/2 the core speed you can't select a different frequency

2) The max frequency the PIT will run at in your specific case will be 50 MHz (1/2 core speed = 100 MHz/2 = 5 0MHz)

3) Using one any of the always enabled channels will not affect the capability of the DMA to perform either internal or

external memory transfers

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