Clock: Incorrect time in Watchdog::clock (for periods > 1 second).
Closed this issue · 3 comments
I use Cosa Watchdog with large timeout periods (1024ms and above) and it seems my Alarms are not triggered at the right time, e.g for 1024ms watchdog period, a 10 seconds alarm is triggered only every 12 seconds.
Additional delay is even worse when using bigger timeouts.
After investigating, I think the problem is with ::Clock::tick() method implementation:
void tick(uint16_t ms)
{
synchronized {
m_msec += ms;
if (m_msec >= 1000) {
m_msec -= 1000 + m_cal;
m_sec += 1;
dispatch();
}
}
}
As one can see, m_sec will be incorrect if m_msec m_msec >= 2000 ms, however this can happen when the argument ms is > 1000 ms.
That method is called by ISR(WDT_vect):
if (Watchdog::s_clock != NULL)
Watchdog::s_clock->tick(Watchdog::s_ms_per_tick);
where s_ms_per_tick can be 1024ms or above (up to 8 seconds).
Yes, it looks like the code is written with the assumption that the Watchdog period is less than 1 second. Might need to write this a "while (m_msec >= 1000) { m_msec += 1000 + m_cal; m_sec +=1; }" and the dispatch().
Did a quick update to avoid this error. Please see commit a6cbc71. Test briefly with CosaAlarm.ino and USE_WATCHDOG with 2048 ms period.
Hi Mikael, thanks for the quick fix. I'll update and run my program again this week when I find some time.