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Adafruit QT Py ESP32-S3 No PSRAM
A tiny development board featuring the ESP32-S3, offering USB-C connectivity and designed for space-constrained applications.
21.7 × 17.8 mm
ESP32-S3
MCU
240MHz
clock
8MB
flash
512KB
SRAM
16· 8 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
16 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 5 | TXA6T5PWM | uart | adc · touch · uart | |
| 2 | 6 | SCLA5T6PWM | safe | adc · touch · i2c | |
| 3 | 7 | SDAA4T7PWM | safe | adc · touch · i2c | |
| 4 | 8 | A3T8PWM | safe | adc · touch | |
| 5 | 9 | A2T9PWM | strapping | adc · touch | |
| 6 | 16 | RXA7PWM | uart | adc · uart | |
| 7 | 17 | A1PWM | safe | adc | |
| 8 | 18 | A0PWM | safe | adc | |
| 9 | 35 | MOSIPWM | strapping | spi | |
| 10 | 36 | SCKPWM | strapping | spi | |
| 11 | 37 | MISOPWM | strapping | spi | |
| 12 | 38 | NEOPIXEL_POWERPWM | strapping | - | |
| 13 | 39 | PIN_NEOPIXELPWM | strapping | - | |
| 14 | 40 | SCL1PWM | strapping | - | |
| 15 | 41 | SDA1PWM | strapping | - | |
| 16 | 42 | SSPWM | strapping | spi |
Start with these
7 pins with no boot or system involvementTXA6SCLA5SDAA4A3T8RXA7A1PWMA0PWM
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 |
|---|---|---|---|
| PIN_NEOPIXEL | MTCK (GPIO39) | Default JTAG debugging TCK pin. If JTAG is needed, this pin must be free; it may also be used internally for PSRAM chip select on certain modules, so avoid repurposing it. | Other |
| SCL1 | MTDO (GPIO40) | Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality. | Other |
| SDA1 | MTDI (GPIO41) | Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available. | Other |
| SS | 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 |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| A2 | 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 |
| MOSI | FSPID / PSRAM_D0 | In modules with octal PSRAM, this pin is connected to the PSRAM data line. It is reserved for memory interface and not free for general GPIO when flash/PSRAM is present. | Flash |
| SCK | FSPICLK / PSRAM_CLK | In modules with octal PSRAM, this pin drives the PSRAM clock. It must be dedicated to the memory interface, not used as a regular GPIO when that interface is in use. | Flash |
| MISO | FSPIQ / PSRAM_DQS | In modules with octal PSRAM, this pin is connected to the PSRAM’s DQS signal. It cannot be repurposed without disrupting the PSRAM/flash communication. | Flash |
| NEOPIXEL_POWER | FSPIWP | On flash-equipped chips, this pin is tied to the flash’s WP# (or D3) line. It should be avoided for other use, as it’s needed 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 The Adafruit QT Py ESP32-S3 No PSRAM pinout brings out 16 GPIO pins at a 2.54 mm pitch - every one of them usable in your project. For peripherals, I²C is…
The Adafruit QT Py ESP32-S3 No PSRAM pinout brings out 16 GPIO pins at a 2.54 mm pitch - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO7 and SCL on GPIO6; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO5 and GPIO16 cover serial logging and flashing.
On the analog side there are 8 ADC-capable pins for sensors and battery monitoring and 5 capacitive-touch inputs.
If you want zero surprises, TX, SCL, SDA, A3 and 3 more are free of any such role - the safest first picks. 4 of the exposed pins carry boot-time or system duties on the ESP32-S3 (PIN_NEOPIXEL, SCL1, SDA1 and 1 more).
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 GPIO6 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"▸
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 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(6, OUTPUT);
}
void loop() {
digitalWrite(6, HIGH); delay(500);
digitalWrite(6, LOW); delay(500);
}board to selectesp32-s3-devkitc-1⧉ copy
[env:adafruit_qtpy_esp32s3_nopsram]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600Find 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: adafruit_qtpy_esp32s3_nopsram
framework:
type: esp-idf
# blink - GPIO6
output:
- platform: gpio
pin: 6
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 · 21.7 × 17.8 mmCompute
MCU
ESP32-S3
Clock
240 MHz
SRAM · Flash
512 KB · 8MB
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
5.0 LE
Antenna
PCB
I/O
GPIO · ADC
16 · 8
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
21.7 × 17.8 mm · pin pitch 2.54 mm
The Adafruit QT Py ESP32-S3 No PSRAM 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
At 21.7 × 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 $12.50 - less than the ~$30 most ESP32-S3 boards go for.
The small footprint costs pins: 16 GPIO are broken out, versus 22 or so on a full-size board.
Onboard you'll find a STEMMA QT connector, an addressable RGB LED (GPIO39) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
Where to buy
prices are typical street pricesAdafruit QT Py ESP32-S3 No PSRAM
$12.50per unit, typical
Resources
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