ESP32 SRAM in RTC

[slaughterjim]

Hello,
I am trying to set pointers into SRAM in the RTC to preserve "counts" through a deep sleep/wakeup via EXT1 cycle.
I get an exception and core dump. When I back out the code I do not get the exception and core dump.
Obviously I am access memory that is protected or being used?
Here are my defines for the pointers into SRAM:
//RTC SRAM Memory - Preserved during a sleep/wakeup cycle
#define DOC_SRAM_ADDRESS_0010 0x400C0010
#define DOC_SRAM_ADDRESS_0020 0x400C0020
I this legal?
How do I preserve variables through the deep sleep/wakeup cycle?
Thanks.
JWS