The overview, with examples running, is on the board page.
The Seeed XIAO ESP32-S3
The ESP32-S3 on a thumbnail: 21 by 17.5 mm, fourteen pads, USB-C, and a yellow LED that lights on LOW.
What it is
The same Xtensa LX7 chip as the ESP32-S3-DevKitC-1,
at 240 MHz, on the XIAO family's outline: seven castellated pads down each
long edge, 0.6 inch apart, so it pushes into a breadboard across the channel.
The USB goes to the chip's own USB port, and that is what Serial and the
serial monitor use.
The pin numbers are the XIAO's
The silkscreen numbers are the XIAO family's, as Arduino's "XIAO_ESP32S3"
board defines them, and sketches for this board use them: D0 to D10 are
defined for you, with A0 to A5 and A8 to A10 on the pads that have the
converter.
| Pad | GPIO | Also |
|---|---|---|
D0 |
1 | A0 |
D1 |
2 | A1 |
D2 |
3 | A2 |
D3 |
4 | A3 |
D4 |
5 | A4, I2C SDA |
D5 |
6 | A5, I2C SCL |
D6 |
43 | UART TX |
D7 |
44 | UART RX |
D8 |
7 | A8, SPI SCK |
D9 |
8 | A9, SPI MISO |
D10 |
9 | A10, SPI MOSI |
At the converter's default 12 dB attenuation its full scale is about 2.9 V here, so a potentiometer across 3.3 V reads 4095 over its top eighth.
The user LED
The yellow LED is on GPIO 21, which no pad reaches, wired from 3.3 V to the
pin, so it lights when the pin is LOW. LED_BUILTIN is 21, and
digitalWrite(LED_BUILTIN, LOW) turns it on.
The BOOT and RESET buttons are buttons, not pads. BOOT grounds GPIO 0.
WiFi
It joins Mokxi's simulated network, with the network name and password as properties of the board. There is no radio, no 802.11 and no real internet: Simulated WiFi says what is faithful and what is not. The one exception is the Real internet switch in the Cloud panel, which sends requests for other names out through Mokxi's gateway.
What is modeled
The DevKitC-1 model's chip, whole: one Xtensa LX7 core, GPIO through the GPIO matrix, UART0 and the USB serial port, the timers, ADC1, LEDC PWM and the RMT. Programs built for this board run on the DevKitC-1 and the other way around; the two carry different program strings so each is offered its own examples.
What is not modeled
The camera connector and microSD slot of the Sense version, the battery charger, the PSRAM, the second core and a real radio. Bluetooth LE is simulated: a phone in the editor's Bluetooth pane, not a real radio.
Starter project
XIAO S3 knob is the board across a breadboard with a potentiometer on A0
dimming an LED on D10, and the count printed.