[Cryptech Tech] STM32 FMC problem

[Joachim Strömbergson]

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Aloha!

Pavel Shatov wrote:
> On 13.08.2015 10:22, Joachim Strömbergson wrote:
>> This seems possible, since we have SysTick interrupt, but on the
>> other
>>> hand, that issue is said to only affect revision "A" devices,
>>> while I have "3" next to ST logo on my processor. Very strange.
>> 
>> Have you tried to disable SysTick interrupt during FMC read? 
>> Clearing bit 1 in the SysTick control and status register
>> (STK_CTRL) should disable the interrupt. Or disabling all
>> interrupts during read? Just to make sure if the problem is in the
>> STM32 itself or in the STM23/FPGA interface.
> 
> Well, I actually tried disabling SysTick interrupt by calling 
> NVIC_DisableIRQ(SysTick_IRQn), but that didn't work. I think, I'll
> try your suggestion later today.
> 
> How do I completely disable interrupts, btw?

I thought that would be possible to do in the Nested vectored interrupt
controller (NVIC). Looking at the Programming Manual, chapter 4.3 seems
to suggest that you should be able to disable all but the NMI.

But your test shows that you might also need to disable at least the HW
generated interrupts at the source (like SysTick). Try to disable in
SysTick and NVIC. Clearing bit 11 in th system handler control
and state register (SHCSR) should kill off SysTick.

ST seems to prefer to having to do things at more than one place. (See
for example enabling a peripheral and getting a clock to it.)

- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
========================================================================
 Joachim Strömbergson          Secworks AB          joachim at secworks.se
========================================================================
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