D-duino-32

ESP32 dev board with built-in OLED - perfect for compact UIs, debugging, and quick visual feedback.

Micro-USB

Pinout

ESP32

MCU

240MHz

clock

4MB

flash

520KB

SRAM

14· 11 ADC

GPIO

BLE 4.2+ WiFi

radio

Pinout

16 pins

View:

Pin	GPIO	Labels	Status	Capabilities
1	0	A11T1D3	strapping	adc · touch
2	1	TXD10PWM	uart	uart
3	2	A12T2D4PWM	strapping	adc · touch
4	3	RXD9PWM	uart	uart
5	4	SCLA10T0D2PWM	strapping	adc · touch · i2c
6	5	SDAD1PWM	strapping	i2c
7	12	MISOA15T5D6PWM	strapping	adc · touch · spi
8	13	MOSIA14T4D7PWM	strapping	adc · touch · spi
9	14	SCKA16T6D5PWM	strapping	adc · touch · spi
10	15	SSA13T3D8PWM	strapping	adc · touch · spi
11	25	A18DAC1PWM	safe	adc · dac
12	26	A19DAC2PWM	safe	adc · dac
13	36	A0	strapping	adc
14	39	A3	strapping	adc
15	-	OLED_SCL	safe	-
16	-	OLED_SDA	safe	-

Start with these

2 pins with no boot or system involvement

A18DAC1A19DAC2

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
A11	GPIO0	Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.	Strapping
A12	GPIO2	If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.	Strapping
SCL	GPIO4	Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).	Strapping
SDA	GPIO5	Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.	Strapping
MISO	MTDI (GPIO12)	Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used.	Strapping
MOSI	MTCK (GPIO13)	Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.	Other
SCK	MTMS (GPIO14)	Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.	Other
SS	MTDO (GPIO15)	Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.	Strapping
A0	GPIO36 (SENSOR_VP)	Cannot be used as output; only suitable for input (e.g., analog read).	Other
A3	GPIO39 (SENSOR_VN)	Cannot be used as output; only suitable for input.	Other

Only if you know the tricks

wired to flash or USB - expect a fight

Pin	Label	What to know	Role
TX	U0TXD (GPIO1)	Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console.	USB
RX	U0RXD (GPIO3)	Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads.	USB

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 Across 16 pins, the D-duino-32 exposes 14 GPIO. For peripherals, I²C is mapped to SDA on GPIO5 and SCL on GPIO4; the SPI bus ( MOSI , MISO , SCK , SS ) is…

Across 16 pins, the D-duino-32 exposes 14 GPIO.

For peripherals, I²C is mapped to SDA on GPIO5 and SCL on GPIO4; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.

On the analog side there are 11 ADC-capable pins for sensors and battery monitoring, 7 capacitive-touch inputs and 2 true DAC outputs.

If you want zero surprises, A18 and A19 are free of any such role - the safest first picks. 10 of the exposed pins carry boot-time or system duties on the ESP32 (A11, A12, SCL and 7 more).

Getting started

flash your first firmware in ~2 minutes

Tool:

Connect over USB

Uses a CP2102 bridge - install the CP210x driver if no port appears. Not detected? Hold BOOT while plugging in.

Match & flash

Set the Tools options shown, then click Upload.

Verify it runs

The onboard LED on GPIO25 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: "ESP32 Dev Module"▸

Flash Size: "4MB (32Mb)"▸

Flash Mode: "DIO"▸

Partition Scheme: "Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)" (default)▸

Upload Speed: "921600"▸

▸ every other Tools option — leave at default

Board: ESP32 Dev Module
Flash Size: 4MB (32Mb)
Flash Mode: DIO
Partition Scheme: Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)
Upload Speed: 921600

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

blink.ino Copy

// blink the onboard LED
void setup() {
  pinMode(25, OUTPUT);
}
void loop() {
  digitalWrite(25, HIGH); delay(500);
  digitalWrite(25, LOW);  delay(500);
}

board to selectesp32dev⧉ copy

platformio.ini Copy

[env:d-duino-32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600

Find it: PlatformIO Home ▸ Boards, search esp32dev — or type it after board =.

board to selectesp32dev⧉ copy

device.yaml Copy

esp32:
  board: esp32dev
  variant: d-duino-32
  framework:
    type: esp-idf

# blink - GPIO25
output:
  - platform: gpio
    pin: 25
    id: led_out
light:
  - platform: binary
    name: "LED"
    output: led_out

Find it: search ESPHome's board list for esp32dev (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 esp32 --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

Compute

MCU

ESP32

Clock

240 MHz

SRAM · Flash

520 KB · 4MB

Radio

Wi-Fi

802.11 b/g/n

Bluetooth

4.2 LE

Antenna

PCB

I/O

GPIO · ADC

14 · 11

UART · I²C · SPI

3 · 2 · 4

PWM

16 channels

Power

USB

Micro-USB

Serial

CP2102

Boot address

0x1000

Display

Screen

OLED · 0.96" · 128x64

Driver

SSD1306

Touch

Flashing

Upload · OTA

esptool_py · esp_ota

Flash · Boot mode

DIO · DIO

Sketch · Data

1.25 MB · 320 KB

The D-duino-32 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with DIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.

About this board

At its core is the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.

Only 14 GPIO are broken out, where most ESP32 boards manage about 24 - worth checking the pinout covers what you need.

Onboard you'll find an OLED 0.96" 128x64 display and Reset/Boot buttons.

Resources

ESP32 datasheet espressif.com↗

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