TMS570LS0432 _undefined istruction triggered entering into interrupt routine

Hi all,

I am using the TMS570LS0432 evaluation board. I am trying to use the SCI serial comunication peripheral in interrupt mode, but I have a problem when the interrup

routine sciHighLevelInterrupt is triggered.

Entering in this routine a precompiled instruction (FMXR) is executed, causing a jump to the  _undefined instruction into the Interrupt vector routine.

The execution remain there in a infinite loop because the undefine handler is disabled. 

I read in a forum thread that another guy had the same problem but with another processor type (TMS570LS2016).

The Ti support analysis and the relevant suggestion is reported below in red:

The problem ending up in _undefined or _prefetchAbort is,

that you use a library which supports the device floating-point (FPU),

but your code does not enable the FPU.

At the beginning of an interrupt routine a write to the FPU happens,

which causes the _undefined or _prefetchAbort,

if the FPU is disabled The easiest way to fix the issue

is to enable the FPU by calling the

following function at the beginning of _c_int00() in sys_startup..

;-------------------------------------------------------------------------------

; Enable VFP Unit

.def _coreEnableVfp_

.asmfunc

_coreEnableVfp_

mrc p15, #0x00, r0, c1, c0, #0x02

orr r0, r0, #0xF00000

mcr p15, #0x00, r0, c1, c0, #0x02

mov r0, #0x40000000

fmxr fpexc, r0

bx lr

.endasmfunc

 I am using the --Float_Support VFPv3D16 and I tryed to insert the suggested routine into my source code but the problem is still present.

When the CPU executes the fmxr fpexc, r0  instruction , the _undefined is triggered again.

Please could I have any further suggestion to fix my Issue ?

Thanks in advance for your support.

Best regards

Claudio