XIAO ESP32S3 Sense
XIAO ESP32S3 with a snap-on expansion board adding an OV3660 camera, a PDM microphone and a microSD slot for vision and voice projects.
XIAO ESP32S3 Sense Pinout
31 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | D0A0GPIO1 | safe | adc · touch · pwm | |
| 2 | 2 | D1A1GPIO2 | safe | adc · touch · pwm | |
| 3 | 3 | D2A2GPIO3 | strapping | adc · touch · pwm | |
| 4 | 4 | D3A3GPIO4 | safe | adc · touch · pwm | |
| 5 | 5 | D4A4SDAGPIO5 | safe | adc · touch · pwm · i2c | |
| 6 | 6 | D5A5SCLGPIO6 | safe | adc · touch · pwm · i2c | |
| 7 | 43 | D6TXGPIO43 | uart | uart · pwm | |
| 8 | - | 5V | power | - | 5V power input/output |
| 9 | - | GND | ground | - | |
| 10 | - | 3V3 | power | - | 3.3V power |
| 11 | 9 | D10A10MOSIGPIO9 | strapping | adc · touch · pwm · spi | |
| 12 | 8 | D9A9MISOGPIO8 | safe | adc · touch · pwm · spi | |
| 13 | 7 | D8A8SCKGPIO7 | safe | adc · touch · pwm · spi | |
| 14 | 44 | D7RXGPIO44 | uart | uart · pwm | |
| 15 | 10 | CAM_XMCLKGPIO10 | strapping | adc · touch · pwm | Camera XMCLK on the expansion board, via the B2B connector |
| 16 | 11 | CAM_Y8GPIO11 | strapping | adc · touch · pwm | Camera Y8 on the expansion board, via the B2B connector |
| 17 | 12 | CAM_Y7GPIO12 | strapping | adc · touch · pwm | Camera Y7 on the expansion board, via the B2B connector |
| 18 | 13 | CAM_PCLKGPIO13 | strapping | adc · touch · pwm | Camera PCLK on the expansion board, via the B2B connector |
| 19 | 14 | CAM_Y6GPIO14 | strapping | adc · touch · pwm | Camera Y6 on the expansion board, via the B2B connector |
| 20 | 15 | CAM_Y2GPIO15 | safe | adc · pwm | Camera Y2 on the expansion board, via the B2B connector |
| 21 | 16 | CAM_Y5GPIO16 | safe | adc · pwm | Camera Y5 on the expansion board, via the B2B connector |
| 22 | 17 | CAM_Y3GPIO17 | safe | adc · pwm | Camera Y3 on the expansion board, via the B2B connector |
| 23 | 18 | CAM_Y4GPIO18 | safe | adc · pwm | Camera Y4 on the expansion board, via the B2B connector |
| 24 | 38 | CAM_VSYNCGPIO38 | safe | pwm | Camera VSYNC on the expansion board, via the B2B connector |
| 25 | 39 | CAM_SIOCGPIO39MTCK | strapping | pwm · i2c | Camera SIOC on the expansion board, via the B2B connector; also the MTCK/MTDO JTAG test pad on the back |
| 26 | 40 | CAM_SIODGPIO40MTDO | strapping | pwm · i2c | Camera SIOD on the expansion board, via the B2B connector; also the MTCK/MTDO JTAG test pad on the back |
| 27 | 47 | CAM_HREFGPIO47 | strapping | pwm | Camera HREF on the expansion board, via the B2B connector |
| 28 | 48 | CAM_Y9GPIO48 | strapping | pwm | Camera Y9 on the expansion board, via the B2B connector |
| 29 | 42 | PDM_CLKGPIO42MTMS | strapping | pwm | PDM microphone clock on the expansion board (cut JP1 to free it); also the MTMS test pad on the back |
| 30 | 41 | PDM_DATAGPIO41MTDI | strapping | pwm | PDM microphone data on the expansion board (cut JP2 to free it); also the MTDI test pad on the back |
| 31 | 21 | SD_CSGPIO21LED_BUILTIN | safe | pwm | User LED on the main board, and the microSD chip select on the expansion board (R12 0R; the R11 option to D2 is not fitted) |
Start with these
5 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
23 pins · 7 things to knowD2GPIO3 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.
D6GPIO43 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).
D10GPIO9D9GPIO8D8GPIO7 Used by the microSD slot on the expansion board (shared SPI bus) onboard hardware
Wired to the microSD slot on the expansion board (shared SPI bus) on this board. The pin is yours if you give that up, but nothing else can share it.
- D10
- D9
- D8
D7GPIO44 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.
CAM_XMCLKGPIO10CAM_Y8GPIO11CAM_Y7GPIO12CAM_PCLKGPIO13CAM_Y6GPIO14CAM_Y2GPIO15CAM_Y5GPIO16CAM_Y3GPIO17CAM_Y4GPIO18CAM_VSYNCGPIO38CAM_SIOCGPIO39CAM_SIODGPIO40CAM_HREFGPIO47CAM_Y9GPIO48 Used by the camera on the expansion board onboard hardware
Wired to the camera on the expansion board on this board. The pin is yours if you give that up, but nothing else can share it.
- CAM_XMCLKCamera XMCLK on the expansion board, via the B2B connector
- CAM_Y8Camera Y8 on the expansion board, via the B2B connector
- CAM_Y7Camera Y7 on the expansion board, via the B2B connector
- CAM_PCLKCamera PCLK on the expansion board, via the B2B connector
- CAM_Y6Camera Y6 on the expansion board, via the B2B connector
- CAM_Y2Camera Y2 on the expansion board, via the B2B connector
- CAM_Y5Camera Y5 on the expansion board, via the B2B connector
- CAM_Y3Camera Y3 on the expansion board, via the B2B connector
- CAM_Y4Camera Y4 on the expansion board, via the B2B connector
- CAM_VSYNCCamera VSYNC on the expansion board, via the B2B connector
- CAM_SIOCCamera SIOC on the expansion board, via the B2B connector; also the MTCK/MTDO JTAG test pad on the back
- CAM_SIODCamera SIOD on the expansion board, via the B2B connector; also the MTCK/MTDO JTAG test pad on the back
- CAM_HREFCamera HREF on the expansion board, via the B2B connector
- CAM_Y9Camera Y9 on the expansion board, via the B2B connector
PDM_CLKGPIO42PDM_DATAGPIO41 Used by the PDM microphone on the expansion board onboard hardware
Wired to the PDM microphone on the expansion board on this board. The pin is yours if you give that up, but nothing else can share it.
- PDM_CLKPDM microphone clock on the expansion board (cut JP1 to free it); also the MTMS test pad on the back
- PDM_DATAPDM microphone data on the expansion board (cut JP2 to free it); also the MTDI test pad on the back
SD_CSGPIO21 User LED on the main board, and the microSD chip select on the expansion board (R12 0R; the R11 option to D2 is not fitted) onboard hardware
Wired to the user LED and the expansion board's microSD chip select on this board. The pin is yours if you give that up, but nothing else can share it.
Across 31 pins (2.54 mm pitch), the XIAO ESP32S3 Sense exposes 28 GPIO plus 5V, GND and 3V3 for power.
For peripherals, I²C is mapped to SDA on GPIO5 and SCL on GPIO6; the SPI bus (MOSI, MISO, SCK) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.
On the analog side there are 18 ADC-capable pins for sensors and battery monitoring, PWM on every GPIO and 14 capacitive-touch inputs.
If you want zero surprises, D0, D1, D3, D4 and 1 more are free of any such role - the safest first picks. 23 of the exposed pins carry boot-time or system duties on the ESP32-S3 (D2, D6, D10 and 20 more).
Getting started
flash your first firmware in ~2 minutesBoard: XIAO_ESP32S3 USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO PSRAM: OPI PSRAM Partition Scheme: Default with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// blink the onboard user LED
void setup() {
pinMode(21, OUTPUT);
}
void loop() {
digitalWrite(21, HIGH); delay(500);
digitalWrite(21, LOW); delay(500);
}[env:xiao-esp32s3-sense]
platform = espressif32
board = seeed_xiao_esp32s3
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_opi
build_flags = -DBOARD_HAS_PSRAMseeed_xiao_esp32s3 - or type it after board =.esp32:
board: seeed_xiao_esp32s3
variant: esp32s3
framework:
type: esp-idf
psram:
mode: octal
speed: 80MHz
# blink - GPIO21
output:
- platform: gpio
pin: 21
id: led_out
light:
- platform: binary
name: "LED"
output: led_outseeed_xiao_esp32s3 (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).Good to know
board-specific quirks worth 60 seconds
Almost nothing the expansion board adds lands on the 14-pin header. Seeed's wiki documents that the camera "occupies 14 GPIOs of the ESP32-S3" - GPIO10 to GPIO18 plus GPIO38, GPIO39, GPIO40, GPIO47 and GPIO48 - and none of those are broken out, so the header pinout is identical to the plain XIAO ESP32S3. The PDM microphone sits on GPIO42 (clock) and GPIO41 (data), which reach the expansion board over the B2B…
Almost nothing the expansion board adds lands on the 14-pin header. Seeed's wiki documents that the camera "occupies 14 GPIOs of the ESP32-S3" - GPIO10 to GPIO18 plus GPIO38, GPIO39, GPIO40, GPIO47 and GPIO48 - and none of those are broken out, so the header pinout is identical to the plain XIAO ESP32S3. The PDM microphone sits on GPIO42 (clock) and GPIO41 (data), which reach the expansion board over the B2B connector rather than the header.
The microSD slot shares the board's SPI bus (D8 SCK, D9 MISO, D10 MOSI = GPIO7/8/9) and Seeed's own examples open it with SD.begin(21), i.e. chip select on GPIO21 (the pin that also drives the user LED). Seeed's pin table lists GPIO3, but the expansion board's schematic wires chip select to GPIO21 through R12 (0 ohm); the GPIO3 option (R11) is not fitted. Any other SPI device you add needs its own chip-select pin.
To find out which sensor is fitted, Seeed's camera sketch reads it back at runtime with esp_camera_sensor_get() and compares s->id.PID against OV3660_PID. In the ESP32 camera driver's sensor.h those constants are OV3660_PID = 0x3660 and OV2640_PID = 0x26.
Seeed's Round Display has its own microSD slot on the same bus: use chip select 21 for the Sense slot and D2 for the display's slot. The jumper Seeed calls J3 (JP3 on the expansion board's schematic) does not disconnect the slot: it switches the 3.3 V feed to the slot's pull-up resistors R4-R6. Seeed's camera tutorial adds a caveat: the Sense's pull-up resistors R4-R6 and the display's own pull-ups can stop the card from reading when both slots are fitted - cutting J3 is its fix.
Downloads
Free for non-commercial use, credit espboards.dev · License
Board illustration
The bare XIAO ESP32S3 Sense board drawn to scale at 21 × 17.8 mm, with no pin labels on it. Made for slide decks, wiring diagrams and project write-ups where a photo is too busy. Take the scalable SVG for print or editing, the high-resolution PNG to drop straight in, or the transparent PNG when you need it with no background behind it.
Pinout diagram
Every pin on both sides of the board with its functions, drawn by ESPboards from the ESP32-S3 Series Datasheet v2.2 - the same sheet shown at the top of this page. The PNG is a high-resolution image for screens, the SVG is vector so it stays sharp at any size, and the PDF is laid out to print on A4 or Letter.
Yours to use, share and adapt for non-commercial work, as long as you credit espboards.dev - the full terms and ready-made credit lines are here.
Specifications
ESP32-S3 · 21 × 17.8 mm · vs other ESP32 chips →Dimensions
About this board
At 21 × 17.8 mm it's among the smallest boards in the whole ESP32 family.
At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
Expect to pay about $13.90 - less than the ~$29 most ESP32-S3 boards go for.
28 GPIO are broken out - more than most ESP32-S3 boards, so the pin budget is rarely the constraint.
Onboard you'll find 8MB (OPI) PSRAM, an OV3660 camera (2048x1536), a microSD slot, a microphone (PDM), battery charging via Solder pads, status LEDs (User, Charge) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
The XIAO ESP32S3 Sense is the XIAO ESP32S3 plus a snap-on expansion board that adds a camera, a digital microphone and a microSD slot. The same ESP32-S3R8 with 8 MB PSRAM and 8 MB flash sits underneath, so the 21 x 17.8 mm footprint is unchanged and the board only grows in height - Seeed lists it as 21 x 17.8 x 15 mm with the expansion board fitted. Wireless is unchanged too: a U.FL connector takes the rod antenna that ships in the box, and Seeed's wiki tells you to "take out the antenna inside the package and install it on the connector" for a better Wi-Fi and Bluetooth signal.
Current units ship an OV3660 (3 MP, 2048 x 1536). Seeed's wiki states that the OV2640 (2 MP, 1600 x 1200) used by early boards "has been discontinued, and the subsequent XIAO ESP32-S3 Sense uses the OV3660 camera model", and that the wiki's camera example code still applies to both. The microSD slot takes cards up to 32 GB, formatted FAT32.
Power comes from USB-C at 5 V or a 3.7 V lithium cell on the solder pads, and the expansion board is not free: Seeed rates the Sense at 110 mA Wi-Fi active and 3 mA in deep sleep, against 100 mA and 14 µA for the bare XIAO ESP32S3. Programming runs over the S3's native USB, and arduino-esp32 lists the board as XIAO_ESP32S3 - there is no separate Sense entry - with Tools → PSRAM → "OPI PSRAM" required before the camera works. Seeed also sells a pre-soldered variant.
- Dual-core Xtensa LX7 at up to 240 MHz
- Detachable expansion board carrying a camera, a digital microphone and a microSD slot
- Camera on the detachable expansion board is an OV3660 (3 MP, 2048x1536); early units shipped an OV2640 (2 MP, 1600x1200) before it was discontinued
- Onboard microSD slot for cards up to 32 GB, formatted FAT32
- Supports WiFi 4 (802.11 b/g/n), Bluetooth 5.0 LE and Bluetooth Mesh
- Ultra-small size (21 x 17.8 x 15 mm with the expansion board fitted)
Where to buy
prices are typical street pricesResources
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