On 07/01/2015 05:02 AM, Ariel D'Alessandro wrote:
(Sorry, I sent the last mail with an incorrect mail account)
El 01/07/15 a las 08:30, adalessandro escibió:
El 29/06/15 a las 01:47, Guenter Roeck escibió:
On 06/28/2015 11:13 AM, Ariel D'Alessandro wrote:
+/* Timeout values in seconds */
+#define LPC_WDT_DEF_TIMEOUT 1
+
One second ? This is highly unusual. 30 or 60 seconds is more common,
and one second would be very challenging for user space.
Any special reason for using such a tight default ?
Considering that LPC18xx Watchdog has a fixed divide-by-4 clock
pre-scaler and a 24-bit counter and that Watchdog clock runs at a fixed
frequency of 12MHz, timeout range goes from 1 to 5 seconds.
I think you're right, 1 sec is very challenging, so it's 5 secs then.
Ultimately you might want to consider a soft timer as backup to the system
timeout. But that can be done later if/when needed.
I understand your point, but just to be sure, what do mean by soft timer?
A kernel function which pings the watchdog periodically even if the
watchdog is open.
Example: Timeout is set to 30 seconds. Since the HW watchdog times out
earlier than that, it needs to be pinged regularly (eg every 2.5 seconds).
The kernel does that with a timer unless user space does not ping the
watchdog within the configured interval of 30 seconds.
Guenter
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