ESP32-C3 Low-Power Mode

ESP32-C3 has an advanced Power Management Unit (PMU), which can flexibly power up different power domains of the chip, to achieve the best balance among chip performance, power consumption, and wakeup latency. ESP32-C3 features four predefined power modes that not only enable developers to fulfill the requirements of various IoT application scenarios but also pass rigorous power consumption certification tests. These power modes have been successfully utilised in numerous IoT projects, including smart lighting. ESP32-C3 offers an array of low-power solutions for these power modes, which can serve as a reference for developers to select and configure based on their specific requirements. The four power modes are as follows:

  • Active mode: The CPU and chip RF are powered on. The chip can receive, transmit, or listen.

  • Modem-sleep mode: The CPU is operational, and the clock speed can be reduced. Wi-Fi base band, Bluetooth LE base band, and RF are disabled, but Wi-Fi and Bluetooth LE connection can remain active.

  • Light-sleep mode: The CPU is paused. Wi-Fi base band, Bluetooth LE base band, and RF are disabled. Any wakeup events (MAC, host, RTC timer, or external interrupts) will wake up the chip. In automatic Light-sleep mode, Wi-Fi or Bluetooth LE can remain connected.

  • Deep-sleep mode: CPU and most peripherals are powered down. Only the RTC memory and RTC peripherals are powered on. Wi-Fi base band, Bluetooth LE base band, and RF module are disabled.

By default, ESP32-C3 will enter Active mode after reset. In Active mode, all parts of ESP32-C3 work properly. When the CPU is not needed to operate continuously, such as when waiting for external activity to wake up, the chip can enter one of the low-power modes. Developers can select various power modes based on specific power consumption, wakeup delay, and available wakeup source requirements. With the exception of the Active mode, the other three modes are low-power modes. Table 12.2 lists the differences between the three low-power modes.

Table 12.2. Differences between the three low-power modes

Wi-Fi connection and Bluetooth LE connectionRemainRemainDisconnectedDisconnected
System clockOnOffOff