Pigeon has two watchdogs. The first watchdog is inside SoC and the second is chip STWD100 connected to the GPIOs.
Broadcom SoC watchdog
Broadcom SoC has a built-in hardware watchdog timer. By default Broadcom SoC watchdog is on. You can check the status of the watchdog:
dmesg | grep watchdog chkconfig watchdog
If you want to check watchdog service:
systemctl status watchdog.service
If you have to change the configuration of watchdog, edit /etc/watchdog.conf file.
Pigeon has watchdog chip STWD100 controlled by GPIO, according to the table below.
Table 1. Watchdog GPIO
|Enable watchdog - EN||GPIO5|
|Watchdog input - WDI||GPIO44|
Enable signal is active low. By default enable signal is high (GPIO5 = 1), so the watchdog is not active.
If EN signal is active then the Watchdog input (WDI) has to be toggled within the watchdog timeout period (1 second), otherwise the reset signal is asserted. The watchdog timer is cleared either:
- by toggling WDI input high to low,
- by a pulse on enable pin EN,
- by a transition on watchdog output (reset).
The pulses on WDI input with a duration of at least 1 µs are detected.
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