µTasker Forum

µTasker Forum => NXP^TM M522XX, KINETIS and i.MX RT => Topic started by: neil on February 08, 2009, 06:47:26 PM

Title: crystal value and PLL
Post by: neil on February 08, 2009, 06:47:26 PM

Hi mark,
  I am designing for the 80MHz 52259 processor,and see on the schematic it uses a 48MHz crystal. Does utasker assume that its a 48MHz crystal attached so it can work out the PLL values?

Neil

Title: Re: crystal value and PLL
Post by: mark on February 08, 2009, 07:23:31 PM

Neil

The crystal value is a parameter and this is flexible. Any crystal value can be used and the corresponding PLL parameters configured to give the desired PLL output value.

However you should use a 48MHz if you want to use USB from it. USB needs an exact 48MHz reference. Alternatively you can driver a separate 48MHz clock, with crystal derived accuracy and stability, on to the NQ1 port input.

I would however stick with the 48MHz crystal for simplicity.

regards

Mark