main/rtc_wake_stub_example.c (deep_sleep_wake_stub sample)

/* * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Unlicense OR CC0-1.0 */ #include <inttypes.h> #include "esp_sleep.h" #include "esp_cpu.h" #include "esp_rom_sys.h" #include "esp_wake_stub.h" #include "sdkconfig.h" /* * Deep sleep wake stub function is a piece of code that will be loaded into 'RTC Fast Memory'. * The first way is to use the RTC_IRAM_ATTR attribute to place a function into RTC memory, * The second way is to place the function into any source file whose name starts with rtc_wake_stub. * Files names rtc_wake_stub* have their contents automatically put into RTC memory by the linker. * * First, call esp_set_deep_sleep_wake_stub to set the wake stub function as the RTC stub entry, * The wake stub function runs immediately as soon as the chip wakes up - before any normal * initialisation, bootloader, or ESP-IDF code has run. After the wake stub runs, the SoC * can go back to sleep or continue to start ESP-IDF normally. * * Wake stub code must be carefully written, there are some rules for wake stub: * 1) The wake stub code can only access data loaded in RTC memory. * 2) The wake stub code can only call functions implemented in ROM or loaded into RTC Fast Memory. * 3) RTC memory must include any read-only data (.rodata) used by the wake stub. */ // counter value, stored in RTC memory static uint32_t s_count = 0; static const uint32_t s_max_count = 20; // wakeup_cause stored in RTC memory static uint32_t wakeup_cause; // wakeup_time from CPU start to wake stub static uint32_t wakeup_time; // wake up stub function stored in RTC memory void wake_stub_example(void) { // Get wakeup time. wakeup_time = esp_cpu_get_cycle_count() / esp_rom_get_cpu_ticks_per_us(); // Get wakeup cause. wakeup_cause = esp_wake_stub_get_wakeup_cause(); // Increment the counter. s_count++; // Print the counter value and wakeup cause. ESP_RTC_LOGI("wake stub: wakeup count is %d, wakeup cause is %d, wakeup cost %ld us", s_count, wakeup_cause, wakeup_time); if (s_count >= s_max_count) { // Reset s_count s_count = 0; // Set the default wake stub. // There is a default version of this function provided in esp-idf. esp_default_wake_deep_sleep(); // Return from the wake stub function to continue // booting the firmware. return; } // s_count is < s_max_count, go back to deep sleep. // Set wakeup time in stub, if need to check GPIOs or read some sensor periodically in the stub. esp_wake_stub_set_wakeup_time(CONFIG_WAKE_UP_TIME*1000000); // Print status. ESP_RTC_LOGI("wake stub: going to deep sleep"); // Set stub entry, then going to deep sleep again. esp_wake_stub_sleep(&wake_stub_example); }