ColdFire/68K Microcontrollers and ProcessorsのトピックRe: MCF51JM , XTAL Oscillator not running

MCF51JM , XTAL Oscillator not running

Bloodhound — Thu, 11 Jun 2009 14:56:19 GMT

Hi All,

I'd been working with a prototype PCB using a MCF51JM, everything was progressing fine, then it just seemed to stop working, BDM cannot connect.

This is what I've found.

There is no oscillation on the XTAL/EXTAL pins (It's has an 8MHz crystal).

Reset line is pulsing every 40uS.

So far I've swapped in a new CPU, swapped 5V regs (it has a reset line) and the crystal, but this thing refuses to work now. Before it just quit it had been working ok and I was exectuing code on the MCU, so I know my circuit design is ok to at least make the thing functional.

So what might stop this CPU from running?

Thanks,

Ross

Re: MCF51JM , XTAL Oscillator not running

Wanderer — Tue, 13 Mar 2012 05:09:27 GMT

I have a similar issue, but the reset line has a sawtooth from 2.6V to 3.3V. What did you find was the issue with your board?

Thanks, gj

Re: MCF51JM , XTAL Oscillator not running

TomE — Tue, 13 Mar 2012 10:39:12 GMT

Search this forum for "KCF51JM", "crystal", "oscillator" and"MCGSC_OSCINIT".

This might be a starting point:

https://community.freescale.com/message/102052#102052

Tom