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Cytron Maker Feather AIoT S3
A Feather-format ESP32-S3 board by Cytron, designed for AIoT applications with various peripheral support.
58.4 × 22.9 mm
ESP32-S3
MCU
240MHz
clock
8MB
flash
512KB
SRAM
20· 12 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
21 pins · 2.54 mm pitch| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | BOOT | strapping | - | |
| 2 | 2 | LED_BUILTINPWM | safe | - | |
| 3 | 3 | BUTTONPWM | strapping | - | |
| 4 | 4 | A4T4PWM | safe | adc · touch | |
| 5 | 5 | A3T5PWM | safe | adc · touch | |
| 6 | 6 | A2T6PWM | safe | adc · touch | |
| 7 | 7 | SSA5T7PWM | safe | adc · touch · spi | |
| 8 | 8 | MOSIA7T8PWM | safe | adc · touch · spi | |
| 9 | 9 | A1T9PWM | strapping | adc · touch | |
| 10 | 10 | A0T10PWM | strapping | adc · touch | |
| 11 | 11 | VP_ENPWM | strapping | - | |
| 12 | 12 | BUZZERPWM | strapping | - | |
| 13 | 13 | VINVBATTVOLTAGE_MONITORA12PWM | power | adc | |
| 14 | 14 | A11T14PWM | strapping | adc · touch | |
| 15 | 15 | TXA10PWM | uart | adc · uart | |
| 16 | 16 | RXA9PWM | uart | adc · uart | |
| 17 | 17 | SCKA6PWM | safe | adc · spi | |
| 18 | 18 | MISOA8PWM | safe | adc · spi | |
| 19 | 41 | SCLPWM | strapping | i2c | |
| 20 | 42 | SDAPWM | strapping | i2c | |
| 21 | 46 | RGB_BUILTIN | strapping | - |
Start with these
10 pins with no boot or system involvementLED_BUILTINPWMA4T4A3T5A2T6SSA5MOSIA7TXA10RXA9SCKA6MISOA8
Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| BOOT | GPIO0 | Must be pulled high (default) or low (to enter UART download mode) at reset. Using it for other functions can interfere with boot mode configuration. | Strapping |
| BUTTON | GPIO3 | Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface. | Strapping |
| SCL | MTDI (GPIO41) | Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available. | Other |
| SDA | MTMS (GPIO42) | Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB). | Other |
| RGB_BUILTIN | GPIO46 | Must be at a defined level during reset (with GPIO0) to select normal or download boot and UART/USB print mode. This pin is input-only (no output drive), so it should be left for its intended strapping function. | Strapping |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| A1 | FSPIHD | Connected to external flash (data/hold signal) on most modules. Not recommended for use as GPIO, since it must remain dedicated to flash communication. | Flash |
| A0 | FSPICS0 | Used to select the external flash chip. It is required for flash access and cannot be repurposed without losing flash connectivity | Flash |
| VP_EN | FSPID | Used as a data line for flash (and in-package PSRAM). It should not be used as GPIO when the flash/PSRAM is in use. | Flash |
| BUZZER | FSPICLK | Drives the flash (and PSRAM) clock. This critical signal must be reserved for memory and not used as general GPIO. | Flash |
| A11 | FSPIWP | Connected to external flash (data/write-protect signal). Not recommended as GPIO because it’s reserved for flash operations. | Flash |
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes Across 21 pins (2.54 mm pitch), the Cytron Maker Feather AIoT S3 exposes 20 GPIO plus VIN for power. Peripheral wiring is straightforward: I²C is mapped to SDA…
Across 21 pins (2.54 mm pitch), the Cytron Maker Feather AIoT S3 exposes 20 GPIO plus VIN for power.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO42 and SCL on GPIO41; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO15 and GPIO16 cover serial logging and flashing.
Beyond plain digital I/O you get 12 ADC-capable pins for sensors and battery monitoring and 8 capacitive-touch inputs.
5 of the exposed pins carry boot-time or system duties on the ESP32-S3 (BOOT, BUTTON, SCL and 2 more) - check the guidance above before wiring anything to them. LED_BUILTIN, A4, A3, A2 and 6 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Native USB - shows up as a port right away, no driver needed. Not detected? Hold BOOT while plugging in.
2
Match & flash
Set the Tools options shown, then click Upload.
3
Verify it runs
The onboard LED on GPIO2 blinks - swap the pin if your board's LED differs.
Set these in Tools · leave everything else at default
Arduino IDE 2.x — Tools Copy
Board: "ESP32S3 Dev Module"▸
USB CDC On Boot: "Enabled"▸
Flash Size: "8MB (64Mb)"▸
Flash Mode: "DIO"▸
PSRAM: "OPI PSRAM"▸
Partition Scheme: "8M with spiffs (3MB APP / 1.5MB SPIFFS)" (default)▸
Upload Speed: "921600"▸
▸ every other Tools option — leave at default
Board: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO PSRAM: OPI PSRAM Partition Scheme: 8M with spiffs (3MB APP / 1.5MB SPIFFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S3 Dev Module
// blink the onboard LED
void setup() {
pinMode(2, OUTPUT);
}
void loop() {
digitalWrite(2, HIGH); delay(500);
digitalWrite(2, LOW); delay(500);
}board to selectesp32-s3-devkitc-1⧉ copy
[env:cytron_maker_feather_aiot_s3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_opi
build_flags = -DBOARD_HAS_PSRAMFind it: PlatformIO Home ▸ Boards, search
esp32-s3-devkitc-1 — or type it after board =.board to selectesp32-s3-devkitc-1⧉ copy
esp32:
board: esp32-s3-devkitc-1
variant: cytron_maker_feather_aiot_s3
framework:
type: esp-idf
psram:
mode: octal
speed: 80MHz
# blink - GPIO2
output:
- platform: gpio
pin: 2
id: led_out
light:
- platform: binary
name: "LED"
output: led_outFind it: search ESPHome's board list for
esp32-s3-devkitc-1 (same ids as PlatformIO).esptool doesn't pick board settings — a prebuilt .bin already has them baked in. This is just the raw flash command.
esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Build details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32-S3 · 58.4 × 22.9 mmCompute
MCU
ESP32-S3
Clock
240 MHz
SRAM · Flash
512 KB · 8MB · 8MB (OPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
5.0 LE
Antenna
PCB
I/O
GPIO · ADC
20 · 12
UART · I²C · SPI
3 · 2 · 4
PWM
8 channels
Power
USB
USB-C
Serial
Native (CDC)
Boot address
0x0
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · QIO
Sketch · Data
1.25 MB · 320 KB
58.4 × 22.9 mm · pin pitch 2.54 mm
The Cytron Maker Feather AIoT S3 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with QIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.
About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
At $19.95 it's cheaper than most ESP32-S3 boards, which usually run around $30.
Around the module: 8MB (OPI) PSRAM, a STEMMA QT connector, an addressable RGB LED (GPIO46), a buzzer, battery charging via JST-PH 2.0, status LEDs (Power, VPeripheral, Charge, User) and Reset/Boot/User buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
- 11 GPIO status indicator LEDs
- Switchable VPeripheral power rail for 2 of the 3 Maker Ports
- Onboard battery voltage monitor on GPIO13
- Piezo buzzer with mute switch
Where to buy
prices are typical street pricesCytron Maker Feather AIoT S3
$19.95per unit, typical
Resources
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