[Reset] A spurious watchdog reset occurs when ESP32 is powered up or wakes up from Deep-sleep

Affected revisions: v0.0

Description

A spurious watchdog reset occurs when ESP32 is powered up or wakes up from Deep-sleep.

Workarounds

To work around the watchdog reset when waking from Deep-sleep, the CPU can execute a program from RTC fast memory. This program must clear the illegal access flag in the cache MMU as follows:

Set the PRO_CACHE_MMU_IA_CLR bit in DPORT_PRO_CACHE_CTRL1_REG to 1.

Clear this bit.

During initial power-up the spurious watchdog reset cannot be worked around, but ESP32 will boot normally after this reset.

Solution

Fixed in chip revision v1.0.