UM PROS3

by Unexpected Maker

An advanced ESP32-S3 board by Unexpected Maker, featuring ESD protection, castellated headers, and extensive Flash and PSRAM, suitable for professional applications.

USB-C Native USB

Buy · $29.95 Pinout Datasheet ↗

53 × 17.8 mm

ESP32-S3

MCU

240MHz

clock

16MB

flash

512KB

SRAM

24· 14 ADC

GPIO

BLE 5.0+ WiFi

radio

Pinout

24 pins · 2.54 mm pitch

View:

Pin	GPIO	Labels	Status	Capabilities
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	12	A11T12PWM	strapping	adc · touch
12	13	A12T13PWM	strapping	adc · touch
13	14	A13T14PWM	strapping	adc · touch
14	15	A14PWM	safe	adc
15	16	A15PWM	safe	adc
16	17	RGB_PWRLDO2PWM	safe	-
17	18	RGB_DATAPWM	safe	-
18	33	VBUS_SENSEPWM	strapping	-
19	34	SSPWM	strapping	spi
20	35	MOSISDOPWM	strapping	spi
21	36	SCKPWM	strapping	spi
22	37	MISOSDIPWM	strapping	spi
23	43	TXPWM	strapping	uart
24	44	RXPWM	strapping	uart

Start with these

11 pins with no boot or system involvement

A0T1A1T2A3T4A4T5A5T6A6T7SDAA7A14PWMA15PWMRGB_PWRLDO2RGB_DATAPWM

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
A2	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	FSPIHD	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.	Other
VBAT_SENSE	FSPICS0	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.	Other
A11	FSPICLK	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.	Other
A12	FSPIQ	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.	Other
A13	FSPIWP	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.	Other
TX	U0TXD (GPIO43)	Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).	Other
RX	U0RXD (GPIO44)	Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.	Other

Only if you know the tricks

wired to flash or USB - expect a fight

Pin	Label	What to know	Role
VBUS_SENSE	SPIIO4 (GPIO33)	The datasheet keeps GPIO33-37 for "the higher 4 bits data line interface and DQS interface for the SPI0/1 interface in 8-line SPI mode", so octal-PSRAM modules (N16R8 and friends) consume it and do not break it out. On quad-PSRAM or PSRAM-less parts it is an ordinary GPIO - check which variant your module carries.	Flash
SS	SPIIO5 (GPIO34)	The datasheet keeps GPIO33-37 for "the higher 4 bits data line interface and DQS interface for the SPI0/1 interface in 8-line SPI mode", so octal-PSRAM modules (N16R8 and friends) consume it and do not break it out. On quad-PSRAM or PSRAM-less parts it is an ordinary GPIO - check which variant your module carries.	Flash
MOSI	SPIIO6 (GPIO35)	The datasheet keeps GPIO33-37 for "the higher 4 bits data line interface and DQS interface for the SPI0/1 interface in 8-line SPI mode", so octal-PSRAM modules (N16R8 and friends) consume it and do not break it out. On quad-PSRAM or PSRAM-less parts it is an ordinary GPIO - check which variant your module carries.	Flash
SCK	SPIIO7 (GPIO36)	The datasheet keeps GPIO33-37 for "the higher 4 bits data line interface and DQS interface for the SPI0/1 interface in 8-line SPI mode", so octal-PSRAM modules (N16R8 and friends) consume it and do not break it out. On quad-PSRAM or PSRAM-less parts it is an ordinary GPIO - check which variant your module carries.	Flash
MISO	SPIDQS (GPIO37)	The datasheet keeps GPIO33-37 for "the higher 4 bits data line interface and DQS interface for the SPI0/1 interface in 8-line SPI mode", so octal-PSRAM modules (N16R8 and friends) consume it and do not break it out. On quad-PSRAM or PSRAM-less parts it is an ordinary GPIO - check which variant your module carries.	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 All 24 pins on the UM PROS3 are usable GPIO, spaced at the standard 2.54 mm pitch. Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL…

All 24 pins on the UM PROS3 are usable GPIO, spaced at the standard 2.54 mm pitch.

Peripheral wiring is straightforward: 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.

Beyond plain digital I/O you get 14 ADC-capable pins for sensors and battery monitoring and 12 capacitive-touch inputs.

8 of the exposed pins carry boot-time or system duties on the ESP32-S3 (A2, SCL, VBAT_SENSE and 5 more) - check the guidance above before wiring anything to them. A0, A1, A3, A4 and 7 more are free of any such role - the safest first picks.

Getting started

flash your first firmware in ~2 minutes

Tool:

Connect over USB

Native USB - shows up as a port right away, no driver needed. Not detected? Hold BOOT while plugging in.

Match & flash

Set the Tools options shown, then click Upload.

Verify it runs

GPIO1 toggles - wire an LED and resistor to it, or change the pin to your board's own LED.

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: "16MB (128Mb)"▸

Flash Mode: "QIO"▸

PSRAM: "QSPI PSRAM"▸

Partition Scheme: "16M Flash (3MB APP/9.9MB FATFS)" (default)▸

Upload Speed: "921600"▸

▸ every other Tools option - leave at default

Board: ESP32S3 Dev Module
USB CDC On Boot: Enabled
Flash Size: 16MB (128Mb)
Flash Mode: QIO
PSRAM: QSPI PSRAM
Partition Scheme: 16M Flash (3MB APP/9.9MB FATFS)
Upload Speed: 921600

Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S3 Dev Module

blink.ino Copy

// 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);
}

board to selectesp32-s3-devkitc-1⧉ copy

platformio.ini Copy

[env:pros3]
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_PSRAM

Find it: PlatformIO Home ▸ Boards, search esp32-s3-devkitc-1 - or type it after board =.

board to selectesp32-s3-devkitc-1⧉ copy

device.yaml Copy

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_out

Find 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.

terminal Copy

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 · QIO

Specifications

ESP32-S3 · 53 × 17.8 mm · vs other ESP32 chips →

Compute

MCU

ESP32-S3

Clock

240 MHz

SRAM · Flash

512 KB · 16MB · 8MB (QSPI) PSRAM

Radio

Wi-Fi

802.11 b/g/n

Bluetooth

5.0 LE

Antenna

I/O

GPIO · ADC

24 · 14

UART · I²C · SPI

3 · 2 · 2

PWM

8 channels

Power

USB

USB-C

Serial

Native (CDC)

Boot address

0x0

Electrical

Input

5V USB-C · 3.7V LiPo

Consumption

Regulator

NCP167

Flashing

Upload · OTA

esptool_py · esp_ota

Flash · Boot mode

QIO · QIO

Sketch · Data

1.25 MB · 320 KB

53 × 17.8 mm · pin pitch 2.54 mm

The UM PROS3 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is QIO 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.

The $29.95 price tag is typical for an ESP32-S3 board.

Around the module: 8MB (QSPI) PSRAM, a STEMMA QT connector, an addressable RGB LED (GPIO18), battery charging (TP4065) via PicoBlade, status LEDs (Power, Charge) and Reset/Boot buttons.

It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.

USB-C with back-feed protection
USB ESD protection (USBLC6-2P6)
Dual 700mA 3.3V LDO regulators (NCP167); LDO2 user-controlled, auto-shuts down in deep sleep
3D high-gain (Fractus) chip antenna
STEMMA QT / Qwiic powered from LDO1
Castellated edge + through-hole headers
LiPo charging ~330mA via TP4065

Where to buy

prices are typical street prices

UM PROS3

$29.95per unit, typical

Resources

Board datasheet esp32s3.com↗ ESP32-S3 datasheet espressif.com↗ ProS3 product page (Unexpected Maker) esp32s3.com↗ProS3 schematic (PDF) github.com↗PlatformIO board definition (um_pros3) github.com↗

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