David Smart

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8 years, 9 months ago.

persist data thru watchdog reset using section(".noinit") not working

I want to create a small logging mechanism that persists the data through reset. I'm using the LPC1768 and the online compiler.

Here's my first pass, which still seems to get cleared following a watchdog event. Thought I'd post now before spending much more time on it.

#define RAMLOG_REC_COUNT 40     // How many log entries
#define RAMLOG_REC_SIZE 20      // How big is each entry

char ldat[RAMLOG_REC_COUNT * RAMLOG_REC_SIZE] __attribute__ ((section (".noinit")));
int RAMLog_index __attribute__ ((section (".noinit")));

RAMLog::RAMLog() {
    enable = false;
}

RAMLog::~RAMLog() {
}

void RAMLog::Dump(void) {
    int i = RAMLog_index + 1;
    while (i != RAMLog_index) {
        char * p = ldat + i * RAMLOG_REC_SIZE;
        if (*p)
            printf("%2d: %s\r\n", i, p);
        i = (i + 1) % RAMLOG_REC_COUNT;
    }
}

void RAMLog::Clear(void) {
    memset(ldat, 0, RAMLOG_REC_COUNT * RAMLOG_REC_SIZE);
    RAMLog_index = 0;
    enable = false;
}

void RAMLog::Enable(void) {
    enable = true;
}

void RAMLog::Log(const char * format, int value) {
    if (enable) {
        char * p = ldat + RAMLog_index * RAMLOG_REC_SIZE;
        snprintf(p, RAMLOG_REC_SIZE, format, value);
        RAMLog_index = (RAMLog_index + 1) % RAMLOG_REC_COUNT;
    }
}

in main(), I have serial port debugger methods to dump the log, enable it for logging, and so on. I can prove it captures records and can dump them out, but they do not persist a watchdog induced reset.

I suspect that the ".noinit" is not a valid section name, but there are zero errors/warnings at compile time, so if that section doesn't exist, it silently ignores the failure...

Has anyone a solution?

1 Answer

Sam Grove
8 years, 9 months ago.

Looks like you've missed a section name that needs to be in the linker script. Have a look at this

http://www.keil.com/support/docs/3480.htm

Accepted Answer

hi Sam, I guess your answer relates to using the offline compiler, and I was hoping to use the online version. Is there any noinit section defined that I can simply layer into?

For the LPC1768, with the 2nd non-contiguous 32K memory, it has always been a slight mystery how much of it the Ethernet stack uses. Perhaps the .noinit could be located in this bank - assuming they can gracefully coexist. I'm far less familiar with other variants.

posted by David Smart 26 Jan 2017

No, the linker script would have to be modified to add a noinit section. I'll take a note about adding support for this given we're thinking about ways to make this easier.

posted by Sam Grove 26 Jan 2017

Is any modification to the online compiler's linker script/scatter file likely in the near term. I'm hitting the same problem in that I need somewhere to stash watchdog state for recovery purposes.

posted by Allen Foster 05 Mar 2017