Yes
No
N/A
UM RMP
Unexpected Maker Reflow Master Pro - an ESP32-S2 reflow-oven controller with a 2.4" TFT, buzzer and dual thermocouple inputs.
ESP32-S2
MCU
240MHz
clock
4MB
flash
320KB
SRAM
26· 20 ADC
GPIO
Wi-Fi
radio
Pinout
26 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | A0T1RGB_DATAPWM | safe | adc · touch | |
| 2 | 2 | A1T2RGB_PWRPWM | safe | adc · touch | |
| 3 | 3 | A2T3VBAT_SENSEPWM | safe | 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 | A9T10PWM | strapping | adc · touch | |
| 11 | 11 | A10T11PWM | strapping | adc · touch | |
| 12 | 12 | A11T12PWM | strapping | adc · touch | |
| 13 | 13 | A12T13PWM | strapping | adc · touch | |
| 14 | 14 | SSA13T14PWM | strapping | adc · touch · spi | |
| 15 | 15 | A14PWM | strapping | adc | |
| 16 | 16 | A15PWM | strapping | adc | |
| 17 | 17 | A16DAC1PWM | safe | adc · dac | |
| 18 | 18 | A17DAC2PWM | safe | adc · dac | |
| 19 | 19 | A18PWM | uart | adc | |
| 20 | 20 | A19PWM | uart | adc | |
| 21 | 21 | VBUS_SENSEPWM | safe | - | |
| 22 | 35 | MOSISDOPWM | strapping | spi | |
| 23 | 36 | SCKPWM | strapping | spi | |
| 24 | 37 | MISOSDIPWM | strapping | spi | |
| 25 | 43 | TXPWM | uart | uart | |
| 26 | 44 | RXPWM | uart | uart |
Start with these
13 pins with no boot or system involvementA0T1A1T2A2T3A3T4A4T5A5T6A6T7SDAA7A16DAC1A17DAC2VBUS_SENSEPWMTXPWMRXPWM
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 |
|---|---|---|---|
| A14 | XTAL_32K_P | If an external 32 kHz crystal is used for RTC, this pin is dedicated to the crystal and cannot be used as GPIO. | Other |
| A15 | XTAL_32K_N | If using an external 32 kHz crystal, this pin is connected to the crystal and should not be used as general I/O. | Other |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| SCL | FSPIHD | Typically used as flash/PSRAM IO line in certain configurations; avoid using as GPIO if flash or PSRAM is present. | Flash |
| A9 | FSPICS0 | Often used as flash chip select in some designs; not available for GPIO when controlling flash. | Flash |
| A10 | FSPID | Used for flash data transfer in certain configurations; should be avoided for general use if flash is connected. | Flash |
| A11 | FSPICLK | Used as flash clock line in some boards; not free for GPIO if driving flash. | Flash |
| A12 | FSPIQ | Used for flash data output in certain configurations; avoid using as GPIO if connected to flash. | Flash |
| SS | FSPIWP | Used as flash write-protect/data line on some modules; not recommended for other usage. | Flash |
| A18 | USB_D- | Used for USB communication; using this pin as general GPIO can interfere with USB functionality. | USB |
| A19 | USB_D+ | Dedicated to USB interface; repurposing as GPIO may disrupt USB connectivity. | USB |
| MOSI | FSPID | Used by internal flash/PSRAM on some ESP32-S2 variants; avoid using as GPIO to prevent conflicts. | Flash |
| SCK | FSPICLK | May be connected to internal flash or used for high-speed SPI; not intended for general GPIO use. | Flash |
| MISO | FSPIQ | Used for internal flash/PSRAM data in some models; should not be repurposed for GPIO. | 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 26 pins on the UM RMP are usable GPIO. Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL on GPIO9; the SPI bus ( MOSI , MISO ,…
All 26 pins on the UM RMP are usable GPIO.
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 20 ADC-capable pins for sensors and battery monitoring, 14 capacitive-touch inputs and 2 true DAC outputs.
2 of the exposed pins carry boot-time or system duties on the ESP32-S2 (A14 and A15) - check the guidance above before wiring anything to them. A0, A1, A2, A3 and 9 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 GPIO1 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: "ESP32S2 Dev Module"▸
USB CDC On Boot: "Enabled"▸
Flash Size: "4MB (32Mb)"▸
Flash Mode: "DIO"▸
PSRAM: "QSPI PSRAM"▸
Partition Scheme: "Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)" (default)▸
Upload Speed: "921600"▸
▸ every other Tools option — leave at default
Board: ESP32S2 Dev Module USB CDC On Boot: Enabled Flash Size: 4MB (32Mb) Flash Mode: DIO PSRAM: QSPI PSRAM Partition Scheme: Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S2 Dev Module
// blink the onboard LED
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}board to selectesp32-s2-saola-1⧉ copy
[env:rmp]
platform = espressif32
board = esp32-s2-saola-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMFind it: PlatformIO Home ▸ Boards, search
esp32-s2-saola-1 — or type it after board =.board to selectesp32-s2-saola-1⧉ copy
esp32:
board: esp32-s2-saola-1
variant: um_rmp
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_outFind it: search ESPHome's board list for
esp32-s2-saola-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 esp32s2 --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-S2Compute
MCU
ESP32-S2
Clock
240 MHz
SRAM · Flash
320 KB · 4MB · 2MB (QSPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n 2.4 GHz
Bluetooth
-
Antenna
External
I/O
GPIO · ADC
26 · 20
UART · I²C · SPI
2 · 1 · 4
PWM
8 channels
Power
USB
USB-C
Serial
Native (CDC)
Boot address
0x1000
Display
Screen
TFT · 2.4"
Driver
-
Touch
No
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · QIO
Sketch · Data
1.25 MB · 320 KB
The UM RMP 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-S2 - a single-core Xtensa with native USB-OTG and no Bluetooth.
At $89.00 it's on the expensive side for an ESP32-S2 board - most land around $20.
Around the module: 2MB (QSPI) PSRAM, a TFT 2.4" display, a STEMMA QT connector, an addressable RGB LED (GPIO1), a buzzer and Navigation/Power buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S2 boards.
- 2x MAX31855 K-type thermocouple sensor ICs
- Dual auxiliary outputs for fans or devices
Where to buy
prices are typical street pricesUM RMP
$89.00per unit, typical
Resources
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