ESP32 is a development board by Espressif that is designed to operate low-power IoT devices. Therefore, it is constructed in a manner that it consumes very less power. ESP32 boards have four to five low-power management modules and five power consumption modes. This write-up will compare two of its power modes.
ESP32 Power Modes
ESP32 modules have five different power modes, ranging from active mode to hibernation. Each mode gets activated depending on the usage of the ESP32 board. These modes are labeled as follows.
- Active Mode
- Light Sleep Mode
- Modem Sleep Mode
- Deep Sleep Mode
- Hibernation Mode
Active Mode of ESP32
In the active mode of ESP32, maximum power is consumed because the whole development board is ON. This is the routine mode of operation of ESP32. The ESP32 development board consists of the following units.
- Peripherals
- Bluetooth
- Wi-Fi
- Radio
- ULP Processor
- Core and Memory
- RTC and its Peripherals
All the above-mentioned blocks are ON during the active mode of ESP32. The power consumption of ESP32 in active mode is about 160 mA to 260 mA and the maximum power-consuming units are Wi-Fi and Bluetooth.
Deep Sleep Mode of ESP32
The second mode which is to be compared with active mode is deep sleep mode. In the deep sleep mode, the least power is consumed among other modes in which ESP32 is ON. In this mode, only Real-Time Communication (RTC) and its peripherals are working along with the Ultra-Low Power ULP Coprocessor. All other units on the ESP32 board are inactive.
In this mode, the battery of ESP32 lasts longer due to power consumption of 0.15mA to only 10uA. It is the power saver of ESP32. The working of ESP32 in this state is done with ULP. The ULP reads data from input and output pins and performs the functions according to them. However, if an interrupt signal is generated, it wakes the CPU. The memory is not stored in this mode. It is erased as soon as the task is finished.
To wake up the ESP32 from this mode, wake-up calls, timers, interrupts, touch sensors, and external wake-up timers can be used.
Comparison Table Between Active Mode and Deep Sleep Mode
| Power Mode | Active Mode | Deep Sleep Mode |
|---|---|---|
| Power Consumption | 160-260mA | 0.15mA-10uA |
| Active Units | Ultra-Low Power Coprocessor RTC and RTC Peripherals, Wi-Fi, Bluetooth, Radio, ESP32 Core and Memory Peripherals. |
Ultra-Low Power Coprocessor and RTC and RTC Peripherals |
| Inactive Units | None | Peripherals, Wi-Fi, Bluetooth, Radio, ESP32 Core, and Memory |
If you want to acquire more knowledge about other power modes of ESP32, read the following article:
Conclusion
The ESP32 is a very efficient power saver because it does not unnecessarily need to keep all its units ON, if not required. If Wi-Fi and Bluetooth are not required to work and ESP32 is not transmitting or receiving data over the cloud, then they can be turned OFF and power can be saved. Similar conditions apply to other units as well. So, deep sleep mode is very useful to save power.
