WEMOS D1 MINI ESP32
ESP32 version of the popular D1 Mini form - great for Wi-Fi-based automation and compact IoT builds.
Pinout
26 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 2 | LED_BUILTINGPIO2 | strapping | - | On-board blue LED (active-LOW) |
| 2 | 3 | TXDGPIO3 | uart | uart | UART0 Transmit (U0_TX) |
| 3 | 1 | RXDGPIO1 | uart | uart | UART0 Receive (U0_RX) |
| 4 | 21 | SDAGPIO21 | safe | i2c | I²C Data Line |
| 5 | 22 | SCLGPIO22 | safe | i2c | I²C Clock Line |
| 6 | 5 | SSGPIO5 | strapping | spi | VSPI Chip-Select |
| 7 | 23 | MOSIGPIO23 | safe | spi | VSPI Master-Out Slave-In |
| 8 | 19 | MISOGPIO19 | safe | spi | VSPI Master-In Slave-Out |
| 9 | 18 | SCKGPIO18 | safe | spi | VSPI Clock |
| 10 | 36 | A0GPIO36 | strapping | adc | ADC1 Channel 0 |
| 11 | 39 | A3GPIO39 | strapping | adc | ADC1 Channel 3 |
| 12 | 32 | A4GPIO32 | safe | adc · touch | ADC1 Channel 4 / Touch 9 |
| 13 | 33 | A5GPIO33 | safe | adc · touch | ADC1 Channel 5 / Touch 8 |
| 14 | 25 | DAC1GPIO25 | safe | dac | 8-bit Digital-to-Analog Converter 1 |
| 15 | 26 | DAC2GPIO26 | safe | dac | 8-bit Digital-to-Analog Converter 2 |
| 16 | 27 | IO27GPIO27 | safe | touch | Touch 7 / RTC-17 |
| 17 | 14 | IO14GPIO14 | strapping | touch · spi | HSPI SCK / Touch 6 |
| 18 | 12 | IO12GPIO12 | strapping | touch · spi | HSPI MISO / Touch 5 |
| 19 | 13 | IO13GPIO13 | strapping | touch · spi | HSPI MOSI / Touch 4 |
| 20 | 15 | IO15GPIO15 | strapping | touch | Boot-strap Pin / Touch 3 |
| 21 | 4 | IO4GPIO4 | strapping | adc · touch | Touch 0 / ADC2 Channel 0 |
| 22 | 16 | RX2GPIO16 | strapping | uart | UART2 Receive |
| 23 | 17 | TX2GPIO17 | strapping | uart | UART2 Transmit |
| 24 | 0 | BOOT_IO0GPIO0 | strapping | touch | Boot-mode Select / Touch 1 (keep HIGH to boot) |
| 25 | 34 | A6GPIO34 | strapping | adc | ADC1 Channel 6 (input-only) |
| 26 | 35 | A7GPIO35 | strapping | adc | ADC1 Channel 7 (input-only) |
Start with these
10 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
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| LED_BUILTIN | GPIO2 | If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure. | Strapping |
| SS | GPIO5 | Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot. | 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 |
| IO14 | MTMS (GPIO14) | Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot. | Other |
| IO12 | 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 |
| IO13 | MTCK (GPIO13) | Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed. | Other |
| IO15 | MTDO (GPIO15) | Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change. | Strapping |
| IO4 | GPIO4 | Sampled at reset for boot config; should not be driven at boot (affects boot mode timing). | Strapping |
| BOOT_IO0 | GPIO0 | Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode. | Strapping |
| A6 | GPIO34 | Cannot be used as output (no drive capability); only suitable for analog/digital input. | Other |
| A7 | GPIO35 | 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 |
|---|---|---|---|
| TXD | 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 |
| RXD | 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 |
| RX2 | GPIO16 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
| TX2 | GPIO17 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
Pinout notes The WEMOS D1 MINI ESP32 pinout brings out 26 GPIO pins at a 2.54 mm pitch - every one of them usable in your project. For peripherals, I²C is mapped to SDA on…
The WEMOS D1 MINI ESP32 pinout brings out 26 GPIO pins at a 2.54 mm pitch - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO21 and SCL on GPIO22, while the SPI bus (MOSI, MISO, SCK, SS) is broken out in full.
On the analog side there are 7 ADC-capable pins for sensors and battery monitoring, 9 capacitive-touch inputs and 2 true DAC outputs.
If you want zero surprises, SDA, SCL, MOSI, MISO and 6 more are free of any such role - the safest first picks. 12 of the exposed pins carry boot-time or system duties on the ESP32 (LED_BUILTIN, SS, A0 and 9 more).
The WEMOS D1 mini ESP32 pinout exposes 26 ESP32 GPIOs on the familiar D label headers-making it shield-compatible while retaining the ESP32’s rich peripherals.
Power rails include 5 V/VIN (USB or external), a regulated 3V3 output, and multiple GND pins. Current draw is typically 80 mA active; the ESP32 chip itself can deep-sleep at ~10 µA, though the CH340 and regulator keep whole-board sleep current well above that.
Default serial lines U0_TX (GPIO1) and U0_RX (GPIO3) connect to the CH340C for programming and logging. Need another UART? Use U2_TX (GPIO17) and U2_RX (GPIO16).
I²C defaults to SDA (GPIO21) and SCL (GPIO22)-changeable in software-and breaks out on the D2/D1 shield pins.
SPI: the primary VSPI bus maps to MOSI GPIO23, MISO GPIO19, SCK GPIO18, and CS GPIO5. An alternate HSPI bus lives on GPIO12–15 when a second SPI device is needed.
Analog: Eight ADC1 channels on GPIO32–GPIO39 remain usable while Wi-Fi is active. Extra ADC2 channels (e.g., GPIO0, 2, 4, 12–15, 25–27) share hardware with Wi-Fi. Dual 8-bit DAC outputs are on GPIO25 and GPIO26.
Capacitive-touch sensing is available on GPIO0, 2, 4, 12–15, 27, 32, 33, perfect for touch-buttons or gesture pads.
Every GPIO can generate PWM up to 40 kHz for LEDs, motors, or buzzers. Watch the boot-strap pins-GPIO0, GPIO2, and GPIO15-which must be at the correct logic level (usually HIGH) at reset to boot normally.
With breadboard-friendly headers, shield compatibility, and the full might of an ESP32 module, the WEMOS D1 mini ESP32 pinout is your compact gateway to advanced connected projects.
Getting started
flash your first firmware in ~2 minutesBoard: D1 Mini32
Flash Size: 4MB · DIO
Upload Speed: 921600
// blink
pinMode(21, OUTPUT);
digitalWrite(21, LOW); // on (often inverted)[env:d1_mini32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32dev
variant: d1_mini32
framework:
type: esp-idf
# blink - GPIO21
output:
- platform: gpio
pin: 21
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binGood to know
board-specific quirks worth 60 seconds
Plenty of these boards ship with a Wemos logo on the silkscreen - but check LOLIN's (Wemos') actual catalog : ESP8266 D1 Mini, D32, and the S2/S3/C3 Minis. A classic-ESP32 D1 Mini has never been in it. The design is generally traced to the MH-ET LIVE MiniKit - an ESP32-WROOM-32 squeezed into the D1 Mini footprint - which we cover as its own board . Everything sold as "D1 Mini ESP32", "mini32" or similar is a generic…
Plenty of these boards ship with a Wemos logo on the silkscreen - but check LOLIN's (Wemos') actual catalog: ESP8266 D1 Mini, D32, and the S2/S3/C3 Minis. A classic-ESP32 D1 Mini has never been in it.
The design is generally traced to the MH-ET LIVE MiniKit - an ESP32-WROOM-32 squeezed into the D1 Mini footprint - which we cover as its own board. Everything sold as "D1 Mini ESP32", "mini32" or similar is a generic take on that design, logo or not.
This isn't a counterfeit of a "real" product - there is no original Wemos version to compare against. The boards are what they are: cheap, plentiful, and standardized enough that Arduino and PlatformIO ship a d1_mini32 board definition for them.
The whole point of this board is the footprint: the outer 16 pins match the ESP8266 D1 Mini , so the large ecosystem of D1 Mini shields - OLED displays, relays, sensor boards - stacks right on . The inner pin rows are the ESP32 bonus GPIOs. The catch is in software: the shield positions map to different GPIO numbers than on the ESP8266. It works out nicely for I2C shields - SDA / SCL sit at the same physical corner…
The whole point of this board is the footprint: the outer 16 pins match the ESP8266 D1 Mini, so the large ecosystem of D1 Mini shields - OLED displays, relays, sensor boards - stacks right on. The inner pin rows are the ESP32 bonus GPIOs.
The catch is in software: the shield positions map to different GPIO numbers than on the ESP8266. It works out nicely for I2C shields - SDA/SCL sit at the same physical corner (GPIO21/22 here vs GPIO4/5 on the ESP8266) - but any sketch written for the 8266 D1 Mini needs its pin numbers translated before it runs here.
Shields that bit-bang specific D-pins (relay shields, WS2812 shields) are the ones to double-check - "D1" and "D2" don't mean the same GPIO on the two boards.
Like other CH340-plus-LDO dev boards, this one keeps sipping power while the ESP32 sleeps: the USB-serial chip, regulator, and LED stay on the 3.3 V rail, so expect board-level deep sleep current in the milliamp range rather than the chip's ~10 µA - the same anatomy measured here on DevKit-style boards . Prototype on this board, then move battery builds to a bare module or a board with a low-quiescent…
Like other CH340-plus-LDO dev boards, this one keeps sipping power while the ESP32 sleeps: the USB-serial chip, regulator, and LED stay on the 3.3 V rail, so expect board-level deep sleep current in the milliamp range rather than the chip's ~10 µA - the same anatomy measured here on DevKit-style boards.
Prototype on this board, then move battery builds to a bare module or a board with a low-quiescent regulator and no serial chip.
Specifications
ESP32 · 39 × 31 mmAbout this board
At its core is the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.
Expect to pay about $6.00 - less than the ~$20 most ESP32 boards go for.
Onboard you'll find Reset buttons.
The D1 Mini ESP32 squeezes a full ESP32-WROOM-32 - dual-core 240 MHz, WiFi and Bluetooth Classic + LE - into the beloved D1 Mini footprint, so it drops straight into the huge ecosystem of D1 Mini shields and mounts.
A quirk of its identity up front: despite the Wemos logo printed on many units, Wemos/LOLIN never actually made this board - their catalog goes from the ESP8266 D1 Mini straight to the D32 and the S2/S3/C3 Minis. The design is generally traced to the MH-ET LIVE MiniKit, and every "D1 Mini ESP32" sold today is a generic take on it. That doesn't make it a worse board - just an unbranded one.
To break out the ESP32's extra GPIOs while keeping the small footprint, the board uses double pin rows: the outer 16 pins match the classic D1 Mini, the inner rows add the rest. Programming runs over Micro-USB through a CH340C USB-serial chip with auto-reset - just mind the driver on a fresh machine.
- Size: 39 mm x 31.5 mm
- Weight: 12G
- Built-in PCB antenna
- Operating voltage: 5V DC
Where to buy
prices are typical street pricesResources
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