EHV bit and ERS bit of C55FMC_MCR can not cleared automatically

[liujinhang]

hi,

i want some help to explain a phenomenon i observed in my 5744P program.

in the end of my program i used the emulation eeprom system to save some data. when the program restart in a short time from last end, i found the EHV bit and ERS bit of C55FMC_MCR will be set all the time without clearing automatically by MCU self.

the phenomenon occurs in low probality.

i want to know the possible reason about the EHV bit and ERS bit of C55FMC_MCR can not cleared by MCU self, and how to clear the EHV bit and ERS bit of C55FMC_MCR mannually.

please help me as soon as possible, thanks very much

[lukaszadrapa]

Hi,

I'm not sure I can understand the description.

You wrote: "when the program restart in a short time from last end" - what does it mean? Does it mean that the MCU has been reset or power off/on occurred?

EHV and ERS bits are cleared by reset. After reset, the MCU does not clear or set these bits itself. It's done only by user.

Regards,

Lukas

[liujinhang]

Hi Lukas,

thanks for your response. "when the program restart in a short time from last end" does mean the MCU power on reset occurs. Because last program end by send "go to sleep " command to SBC.   the SBC will sure cut off the Vcore firstly.

with your idea that the MCU will not set the EHV bit, i didnot think so. because i write the code at my program first code line: 

while(C55FMC.MCR.B.EHV){}

and the program really can not go across thin code line.   the only reason is the C55FMC.MCR.B.EHV is seted before my first code line in main function.

i can confirm that my start code didnot operate the flash.

[lukaszadrapa]

That's weird, this should not happen. Could you take a screenshot of all flash registers when the program is hanging in the while loop?

Lukas

[liujinhang]

hi lukas, 

I am very sorry that i forgot to save program which occurs the problem. these days i try to recurrence the problem, but failed. so i can not supply the creenshot for you now.   i will hang up this problem and will come back if i recurrence the problem.

thank you very much for your timely response.