Bee S3
A compact ESP32-S3 development board designed for general-purpose IoT applications.
Bee S3 Pinout
18 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | VBAT_VOLTAGEPWM | safe | - | |
| 2 | 3 | A3D3T3PWM | strapping | adc · touch | |
| 3 | 4 | A4D4T4PWM | safe | adc · touch | |
| 4 | 5 | SSA5D5T5PWM | safe | adc · touch · spi | |
| 5 | 6 | A6D6T6PWM | safe | adc · touch | |
| 6 | 7 | A7D7T7PWM | safe | adc · touch | |
| 7 | 8 | A8D8T8PWM | safe | adc · touch | |
| 8 | 9 | A9D9T9PWM | strapping | adc · touch | |
| 9 | 10 | A10D10T10PWM | strapping | adc · touch | |
| 10 | 34 | RGB_PWRPWM | safe | - | |
| 11 | 35 | MOSISDOD35PWM | safe | spi | |
| 12 | 36 | SCLD36PWM | safe | i2c | |
| 13 | 37 | SDAD37PWM | safe | i2c | |
| 14 | 38 | MISOSDID38PWM | safe | spi | |
| 15 | 39 | SCKD39PWM | strapping | spi | |
| 16 | 43 | TXD43PWM | uart | uart | |
| 17 | 44 | RXD44PWM | uart | uart | |
| 18 | 48 | RGB_DATA | strapping | - |
Start with these
11 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
7 pins · 6 things to knowA3GPIO3 Bootstrapping pin (controls JTAG signal source) Strapping
Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface.
A9GPIO9A10GPIO10 General-purpose SPI2 (FSPI) IO MUX pins Other
IO MUX pin of the general-purpose SPI2 (FSPI) bus, not of the in-package flash - that sits on GPIO26-32. The datasheet lists it as a priority-2 pin ("can be freely used without restrictions"), so it is only taken if your board wires flash, an SD card or a display to FSPI.
- A9General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- A10General-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
SCKGPIO39 JTAG test clock (MTCK); IO MUX alternates CLK_OUT3 and SUBSPICS1 (chip select on the alternative SUBSPI memory bus, unused on standard modules) JTAG
Default JTAG TCK - keep it free if you debug over JTAG. It is not a flash or PSRAM line on standard modules: those sit on GPIO26-37.
TXGPIO43 UART0 transmit pin (U0TXD), default serial console TX UART
Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).
RXGPIO44 UART0 receive pin (U0RXD), default serial console RX UART
Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.
RGB_DATAGPIO48 Octal SPI differential clock negative leg (SPICLK_N_DIFF), used only by the 1.8 V octal flash/PSRAM variants Other
Only the 1.8 V octal parts (ESP32-S3R8V, ESP32-S3R16V) run the differential memory clock here, and on those the pin works at 1.8 V instead of 3.3 V. On the common 3.3 V modules it is a normal GPIO - several devkits drive their RGB LED from GPIO48.
All 18 pins on the Bee S3 are usable GPIO.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO37 and SCL on GPIO36; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.
Beyond plain digital I/O you get 8 ADC-capable pins for sensors and battery monitoring and 8 capacitive-touch inputs.
7 of the exposed pins carry boot-time or system duties on the ESP32-S3 (A3, A9, A10 and 4 more) - check the guidance above before wiring anything to them. VBAT_VOLTAGE, A4, SS, A6 and 7 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO Partition Scheme: 8M with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}[env:Bee_S3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
# blink - GPIO1
output:
- platform: gpio
pin: 1
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32-s3-devkitc-1 (same ids as PlatformIO).esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32-S3 · vs other ESP32 chips →About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
At $10.00 it's cheaper than most ESP32-S3 boards, which usually run around $29.
Only 18 GPIO are broken out, where most ESP32-S3 boards manage about 23 - worth checking the pinout covers what you need.
Around the module: an addressable RGB LED (GPIO48) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
- 1S LiPo battery connector with onboard battery-voltage monitoring on GPIO1
- No onboard LiPo charger by design, to minimise deep-sleep quiescent current
- Deep-sleep current below 20µA
- Built on the ESP32-S3-MINI-1 module (no PSRAM)
Where to buy
prices are typical street pricesResources
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