Posted on May 17, 2011 at 14:30Thanks for your suggestions!
I moved the static state variables to the SRAM and nothing changed. So I think the FSMC is not the reason. To be sure I checked all FSMC register: They are the same at startup and during the RTC ISR.
Yes it is possible to predict the corruption. With a delay placed after the ''wfi'' command, it seems to work fine. To show how it's basically working, here's some kind of pseudo code:
// Static variable which holds flags
static struct internal internal;
// Sets the wakeup flags
void set_wakup(bool wakeup)
{
if (wakeup)
internal.wakeup_isr = true;
else
internal.iwdg_isr = true;
}
// Checks if a wakeup is required
bool check_wakeup(void)
{
if (internal.iwdg_isr && !internal.wakeup_isr)
return false;
else if (!internal.iwdg_isr && !internal.wakeup_isr)
// Error case
return true;
else
return true;
}
// Changes the power mode
change_power_mode()
{
// Initialize internal data
internal.iwdg_isr = false;
internal.wakeup_isr = false;
...
// Set all register to enter power
...
do {
asm(''wfi'')
// If 10us delay is placed here, everythings seems ok
while(!check_wakeup());
// Set all register to leave power mode
...
}
// RTC alarm ISR
rtc_alarm_isr()
{
if (watchdog_timeout)
set_wakeup(false);
else
set_wakeup(true);
}
Without the delay, on every second interrupt the iwdg_isr variable is not set. But I'm sure it is set. I toggled and measured some IO pins: iwdg_isr is set in the set_wakeup function before it's read by the check wakeup function. Do you see any reason why this delay has an influence on the variable?
Martin
