ESP32-C3 Power Management

Power management algorithm included in ESP-IDF can adjust the advanced peripheral bus (APB) frequency, CPU frequency, and put the chip into Light-sleep mode to run an application at smallest possible power consumption, given the requirements of application components. Additionally, the chip automatically enters Light-sleep mode when idle, reducing the power consumption during application runs. The ESP32-C3's various low-power modes are discussed in detail in Section 12.2. Enabling power management features comes at the cost of increased interrupt latency. Extra latency depends on several factors, such as the CPU frequency, single/dual core mode, whether frequency switch is required.

Applications can acquire/release locks to control the power management algorithm. When an application acquires a lock, the operation of power management algorithm is restricted. When the lock is released, such restrictions are removed. Power management locks have acquire/release counters. If the lock has been acquired a number of times, it needs to be released the same number of times to remove associated restrictions.

ESP32-C3 supports three types of locks described in Table 12.1.

Table 12.1. Power management locks

Power management lockDescription
SP_PM_CPU_FREQ_MAXRequests CPU frequency to be at the maximum value set with esp_pm_configure(). For ESP32-C3, this value can be set to 80 MHz, 160 MHz, or 240 MHz.
ESP_PM_APB_FREQ_MAXRequests the APB frequency to be at the maximum supported value. For ESP32-C3, this is 80 MHz.
ESP_PM_NO_LIGHT_SLEEPDisable automatic switching to Light-sleep mode

Applications can acquire or release power management locks in a way that can accommodate scenarios where power management is not required. For example, driver for a peripheral clocked from APB can request the APB frequency to be set to 80 MHz while the peripheral is used; RTOS can request the CPU to run at the highest configured frequency while there are tasks ready to run; A peripheral driver may need interrupts to be enabled, which means it will have to request disabling Light-sleep mode.

Since requesting higher APB or CPU frequencies or disabling Light-sleep mode causes higher current consumption, please keep the usage of power management locks by components to a minimum.