extern "C" {
#endif
+#define ULP_FSM_PREPARE_SLEEP_CYCLES 2 /*!< Cycles spent by FSM preparing ULP for sleep */
+#define ULP_FSM_WAKEUP_SLEEP_CYCLES 2 /*!< Cycles spent by FSM waking up ULP from sleep */
/**
* @defgroup ulp_registers ULP coprocessor registers
*
* @param period_index wakeup period setting number (0 - 4)
* @param period_us wakeup period, us
+ * @note The ULP FSM requires some time to wakeup before being able to run the program.
+ * Then additional time is reserved after wakeup waiting until the 8M clock is stable.
+ * The FSM also requires time to go to sleep after the program execution is halted.
+ * The minimum wakeup period that may be set up for the ULP
+ * is the total time spent on the above internal tasks.
+ * For a default configuration of the ULP running at 150kHz
+ * the minimum wakeup period is about 160us.
* @return
* - ESP_OK on success
* - ESP_ERR_INVALID_ARG if period_index is out of range
}
uint64_t period_us_64 = period_us;
uint64_t period_cycles = (period_us_64 << RTC_CLK_CAL_FRACT) / esp_clk_slowclk_cal_get();
+ uint64_t min_sleep_period_cycles = ULP_FSM_PREPARE_SLEEP_CYCLES
+ + ULP_FSM_WAKEUP_SLEEP_CYCLES
+ + REG_GET_FIELD(RTC_CNTL_TIMER2_REG, RTC_CNTL_ULPCP_TOUCH_START_WAIT);
+ if (period_cycles < min_sleep_period_cycles) {
+ period_cycles = 0;
+ ESP_LOGW(TAG, "Sleep period clipped to minimum of %d cycles", (uint32_t) min_sleep_period_cycles);
+ } else {
+ period_cycles -= min_sleep_period_cycles;
+ }
REG_SET_FIELD(SENS_ULP_CP_SLEEP_CYC0_REG + period_index * sizeof(uint32_t),
SENS_SLEEP_CYCLES_S0, (uint32_t) period_cycles);
return ESP_OK;