Paul Arnold

MCF5301X Config documentation errors - Serious (?)!

Discussion created by Paul Arnold on Nov 23, 2011
Latest reply on Jun 4, 2017 by TomE

Good morning,

 

We have a MCF53014 based design which is about to hit production.

Latest field tests have shown a problem whereby the board will not always boot.

This has been traced to the oscillator not starting on power up.

 

According to the datasheet address lines A17-A21 are used to configure the chip during reset when RSTOUT is active.

It states that none of the other address lines have any effect.

I noticed on the Freescale dev board schematic that they also drive A16 and A22 during this RSTOUT period.

By driving these lines I can make our board boot reliably.

As we are not driving these lines they are left to float and while they boot 99%+ of the time sometimes they fail.

 

From my tests it appears that A16 needs to be driven high during the RSTOUT period, driving it low prevents the oscillator from starting.

I've yet to determine what A22 does.

 

I'm waiting for a response from support but thought I'd ask if anyone else has had this problem and can confirm my findings ?

 

We are using a 20mhz crystal connected to the chip with the required parallel resistor and capacitors to 0V.

 

I do not have access to a Freescale dev board otherwise I would try my findings on that.

 

If the above is correct and A16/A22 need driving to known states during RSTOUT it's not a simple fix for us (Unless we bodge it by using pull-up/down resistors and don't actively drive the lines) :smileysad:

 

Thanks

Dec

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