topic Clocking problem with MCF52259 Board in ColdFire/68K Microcontrollers and Processors

Clocking problem with MCF52259 Board

rParker — Mon, 22 Aug 2011 22:28:41 GMT

We have developed our own board based on the Tower Demo board. Our board is fitted with a 48MHz crstal as is the demo board but when we run exactly the same application code on our board it seems to be running much slower.

Both CLKMOD pins are tied LOW as default on the TWR demo board and XTAL is tied high (likewise on the demo board). Using the HelloWorld demo serial data is corrupted from our board while the demo works fine.

To make sure its not something to do with the serial line drivers we have put in a never ending loop to flash one of the LEDs at the end of the program. The demo board flashes the LED at a rate of 5Hz while our board flashes the LED at a rate of about 1.67 Hz.

Has anyone got any idea what we are doing wrong?

Thank you in advance

Richard.

Re: Clocking problem with MCF52259 Board

JimDon — Mon, 22 Aug 2011 23:33:56 GMT

Put a scope on CLKOUT and see what you get...

Compare it to the TWR board.

Re: Clocking problem with MCF52259 Board

TomE — Tue, 23 Aug 2011 08:01:55 GMT

5 / 1.67 = 3.

If you think your crystal should be running at 48MHz then it looks like it may be running at 16MHz.

That's been reported here a few times, most recently:

https://community.freescale.com/message/92682#92682

Previous detailed one (just search for "48MHz"):

https://community.freescale.com/message/66903#66903

Tom (A Random Poster)

Re: Clocking problem with MCF52259 Board

rParker — Tue, 23 Aug 2011 17:35:32 GMT

Sorry guys I thought that I had checked the forums before posting but it turns out that I am using a 3rd overtone crystal which would explain the speed problems.

Thanks

Richard

Re: Clocking problem with MCF52259 Board

nnadal2 — Thu, 25 Aug 2011 15:06:53 GMT

I make the same process and took the conclussion we must work with a fundamental frequency crystal. Later Freescale reported similar problems in MCF52259 errata