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Where has the FPU gone???

Question asked by Mark Butcher on Jul 25, 2017
Latest reply on Aug 9, 2017 by Hui_Ma

Hi All

 

Can anyone explain this?

- I have the FRDM-K66F board with the K66FN2M on it and a simple program that operates as normal.
- Then I have a new HW with a K66FX1M on it and am expecting the same code to run on it.

 

The new HW however hard faults when the FPU initialisation takes place (before any clock initialisation).

When I look at the default FPU system registers (after reset and before doing anything else) on the FRDM-K66F I see this

 

 

When I look at the registers on the new HW they are all at 0x00000000 and any code access to the registers is met with the hard fault.

So the question is, what can cause the FPU not to operate (normally) ???? I am expecting it to be to do with a HW connection (maybe a missing power pin?) since the prototype is hand built but there must be a logical explanation to aid in tracking down whatever it is.

Power supply is otherwise 3.3V exactly.

 

Regards

 

Mark

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