UM TinyS3
A compact development board from Unexpected Maker, offering wireless connectivity and ample Flash and PSRAM in a small form factor.
UM TinyS3 Pinout
19 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | A0T1PWM | safe | adc · touch | |
| 2 | 2 | A1T2PWM | safe | adc · touch | |
| 3 | 3 | A2T3PWM | strapping | adc · touch | |
| 4 | 4 | A3T4PWM | safe | adc · touch | |
| 5 | 5 | A4T5PWM | safe | adc · touch | |
| 6 | 6 | A5T6PWM | safe | adc · touch | |
| 7 | 7 | A6T7PWM | safe | adc · touch | |
| 8 | 8 | SDAA7T8PWM | safe | adc · touch · i2c | |
| 9 | 9 | SCLA8T9PWM | strapping | adc · touch · i2c | |
| 10 | 10 | VBAT_SENSEPWM | strapping | - | |
| 11 | 17 | RGB_PWRPWM | safe | - | |
| 12 | 18 | RGB_DATAPWM | safe | - | |
| 13 | 33 | VBUS_SENSEPWM | safe | - | |
| 14 | 34 | SSPWM | safe | spi | |
| 15 | 35 | MOSISDOPWM | safe | spi | |
| 16 | 36 | SCKPWM | safe | spi | |
| 17 | 37 | MISOSDIPWM | safe | spi | |
| 18 | 43 | TXPWM | uart | uart | |
| 19 | 44 | RXPWM | uart | uart |
Start with these
14 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 · 4 things to knowA2GPIO3 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.
SCLGPIO9VBAT_SENSEGPIO10 General-purpose SPI2 (FSPI) IO MUX pins 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.
- SCLGeneral-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- VBAT_SENSEGeneral-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
TXGPIO43 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).
RXGPIO44 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.
The UM TinyS3 pinout brings out 19 GPIO pins - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO8 and SCL on GPIO9; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.
On the analog side there are 9 ADC-capable pins for sensors and battery monitoring and 9 capacitive-touch inputs.
If you want zero surprises, A0, A1, A3, A4 and 10 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, SCL, VBAT_SENSE 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 PSRAM: QSPI PSRAM Partition Scheme: 8M with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}[env:tinys3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMesp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
psram:
mode: quad
speed: 80MHz
# blink - GPIO1
output:
- platform: gpio
pin: 1
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 · 35 × 17.8 mm · vs other ESP32 chips →Dimensions
About this board
At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
Expect to pay about $20.00 - less than the ~$29 most ESP32-S3 boards go for.
Onboard you'll find 8MB (QSPI) PSRAM, an addressable RGB LED (GPIO18), battery charging via JST-PH 2.0 and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
- Battery via header pins + a top JST-PH connector; single 700mA 3V3 LDO; VBAT voltage sensing on GPIO10
- Onboard 3D (ceramic chip) antenna
Where to buy
prices are typical street pricesResources
Similar boards
