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.
Adafruit QT Py ESP32-S3 No PSRAM 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 | safe | spi | |
| 10 | 36 | SCKPWM | safe | spi | |
| 11 | 37 | MISOPWM | safe | spi | |
| 12 | 38 | NEOPIXEL_POWERPWM | safe | - | |
| 13 | 39 | PIN_NEOPIXELPWM | strapping | - | |
| 14 | 40 | SCL1PWM | strapping | - | |
| 15 | 41 | SDA1PWM | strapping | - | |
| 16 | 42 | SSPWM | strapping | spi |
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
5 pins · 5 things to knowA2GPIO9 General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD) 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.
PIN_NEOPIXELGPIO39 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.
SCL1GPIO40 JTAG test data out pin (MTDO) JTAG
Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality.
SDA1GPIO41 JTAG test data in pin (MTDI) JTAG
Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available.
SSGPIO42 JTAG test mode select pin (MTMS) JTAG
Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB).
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 7 more are free of any such role - the safest first picks. 5 of the exposed pins carry boot-time or system duties on the ESP32-S3 (A2, PIN_NEOPIXEL, SCL1 and 2 more).
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 GPIO6 - wire an LED and resistor to it
void setup() {
pinMode(6, OUTPUT);
}
void loop() {
digitalWrite(6, HIGH); delay(500);
digitalWrite(6, LOW); delay(500);
}[env:adafruit_qtpy_esp32s3_nopsram]
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 - GPIO6
output:
- platform: gpio
pin: 6
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 · 21.7 × 17.8 mm · vs other ESP32 chips →Dimensions
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 ~$29 most ESP32-S3 boards go for.
The small footprint costs pins: 16 GPIO are broken out, versus 23 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 pricesResources
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