## Example of putting the main processor to sleep then waking it up# via the ULP after a while#fromesp32importULPfrommachineimportmem32importmachinefromesp32_ulpimportsrc_to_binarysource="""\#define RTC_CNTL_LOW_POWER_ST_REG 0x3FF480c0#define RTC_CNTL_RDY_FOR_WAKEUP BIT(19)entry:        MOVE r0, 2000loop:        WAIT 40000  // at 8 MHz this is 5 msec, if we do this 1000 times that's 5 seconds        SUB r0, r0, 1        jump is_rdy_for_wakeup, eq        jump loopis_rdy_for_wakeup:                   // Read RTC_CNTL_RDY_FOR_WAKEUP bit## This test was described in https://github.com/espressif/esp-idf/issues/8341# See reference manual 31.19.## The main issue with this is that it will hang if the main CPU wasn't in deep sleep.#       READ_RTC_FIELD(RTC_CNTL_LOW_POWER_ST_REG, RTC_CNTL_RDY_FOR_WAKEUP)       AND r0, r0, 1       JUMP is_rdy_for_wakeup, eq    // Retry until the bit is set       WAKE                          // Trigger wake up       HALT                          // Stop the ULP program"""## Compile the ULP code#binary=src_to_binary(source)load_addr,entry_addr=0,0ULP_MEM_BASE=0x50000000ULP_DATA_MASK=0xffff# ULP data is only in lower 16 bitsulp=ULP()ulp.load_binary(load_addr,binary)## The ULP starts out asleep (halted), so set a timer to wake it# up the first time.## ulp.set_wakeup_period(0, 50000)  # use timer0, wakeup after 50.000 cyclesmem32[ULP_MEM_BASE+load_addr]=0x1000ulp.run(entry_addr)print("going to sleep")# I think this should enable ULP wakeupmem32[0x3ff48038 ]=0x200<<10machine.deepsleep()## We won't ever reach this, because WAKE is going to cause the main# processor to reset and start over at the beginning.#print("I am awake again")