Bee Motion ESP32-S2 PIR motion sensor offers GPIOs, over a year of battery life

Smart Bee Designs’ Bee Motion is an ESP32-S2 board with a PIR motion sensor, some GPIOs for expansion, and promising over a year of battery life under the right circumstances.

If the name “Bee Motion” rings a bell, it’s because we covered the Bee Motion Mini board last month with an ESP32-C3 processor and a PIR sensor, but no USB port for programming and no expansion ability. It was just designed to be used as a battery-powered wireless PIR motion sensor. The Bee Motion expands the use cases of the solution, although it only features WiFi connectivity, and loses Bluetooth LE.

Bee Motion ESP32-S2 motion sensor

Bee Motion specifications:

  • Wireless module – Espressif ESP32-S2-MINI-1 module with Espressif ESP32-S2FH4 single-core 32-bit LX7 microcontroller @ up to 240 MHz, RISC-V ultra-low-power co-processor, 320 kB SRAM, 128kB ROM, 2.4 GHz WiFi 4 connectivity, 4MB flash, PCB antenna
  • PIR sensor – Passive infrared motion sensor with dome lens, 5-meter range, 120 degrees FOV
  • USB – 1x USB Type-C port for power and programming
  • Expansion – 2x 12-pin headers with up to 17x GPIO, 13x ADC, touch support, I2C, UART, 5V, 3.3V, and GND
  • Misc – Reset and Boot buttons, battery charging status LED
  • Power Supply
    • 5V DC input via USB-C port
    • Support for LiPo batteries with 2-pin JST connector, charge controller
    • 3.3V regulator
  • Power consumption
    • Deep sleep – 45 uA
    • 80 mAH while on WiFi
  • Dimensions – TBD

Battery-powered ESP32-S2 PIR motion sensor board

Bee Motion pinout diagram
Bee Motion pinout diagram

The Bee Motion ships with headers and a JST connector for a LiPo battery that users could solder to the board if needed. Resources can be found on Github with a 3D printed case, JPG schematics and PCB layout, and a simple Arduino Sketch to put the board in deep sleep mode, wake it up upon motion detection, and toggle a GPIO before getting back to deep sleep.

Smart Bee Designs also used a Power Profiler Kit to measure the power consumption with a similar sketch that also connects to WiFi (as I understand it), and assuming a 100-second active time per day, the board would last well over a year (441 days) with a 1,500 mAh battery.

Bee Motion ESP32-S2 battery life

The Bee Motion ESP32-S2 PIR motion board is sold on Tindie for $19.99 + shipping.

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4 Comments
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William Barath
4 months ago

The core is wrong. Don’t know which spec sheet you copied from but the S2 is an Extensa not a RISC-V

William Barath
4 months ago

yeah I was just trying to update my post with the url but it wouldn’t let me…

“Colour me surprised, the S2 has both an Extensa core and a RISC-V core.

https://www.espressif.com/sites/default/files/documentation/esp32-s2_datasheet_en.pdf

William Barath
4 months ago

The “ULP” RISC-V core operates at around 1% the power of the Extensa core. They don’t say what frequency it operates at , but in the power consumption docs they mention an 8MHz internal clock that is disabled when the ULP core is offline, so it makes sense that the RISC-V core is operating at 8MHz or possibly 16MHz. They quote approx “22 µA @1% duty” while monitoring a sensor, up to “190 µA powered on”.

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