RTC Memory

Espressif reference in SDK

System time will return to zero because of system_restart, but RTC still goes on.

If external hardware resets the chip via EXT_RST or CHIP_EN (such as timed wake-up from Deep-sleep), the RTC timer will be reset. However, RTC Memory may continue.

• Reset by pin EXT_RST
  • RTC memory won’t change
  • RTC timer starts to zero
• Watchdog reset
  • RTC memory won’t change
  • RTC timer won’t change
• system_restart
  • RTC memory won’t change
  • RTC timer won’t change
• Power-on
  • RTC memory contains a random value
  • RTC timer starts from zero
• Reset by pin CHIP_EN
  • RTC memory contains a random value
    • Empirical observation: With brief reset pulses to CHIP_EN, data appeared to remain valid. This may not be immediate - TODO: evaluate This might be the way the five power on/offs method can detect a reset to factor is being requested.
  • RTC timer starts from zero