WEMOS D1 MINI ESP32
ESP32 version of the popular D1 Mini form - great for Wi-Fi-based automation and compact IoT builds.
WEMOS D1 MINI ESP32 Pinout
40 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 2 | IO2GPIO2LED_BUILTIN | strapping | - | On-board blue LED (active-LOW) |
| 2 | 1 | TXDGPIO1 | uart | uart | UART0 Transmit (U0_TX) |
| 3 | 3 | RXDGPIO3 | uart | uart | UART0 Receive (U0_RX) |
| 4 | 21 | IO21GPIO21SDAD2 | safe | i2c | I²C Data Line |
| 5 | 22 | IO22GPIO22SCLD1 | safe | i2c | I²C Clock Line |
| 6 | 5 | IO5GPIO5SSD8 | strapping | spi | VSPI Chip-Select |
| 7 | 23 | IO23GPIO23MOSID7 | safe | spi | VSPI Master-Out Slave-In |
| 8 | 19 | IO19GPIO19MISOD6 | safe | spi | VSPI Master-In Slave-Out |
| 9 | 18 | IO18GPIO18SCKD5 | safe | spi | VSPI Clock |
| 10 | 36 | SVPGPIO36 | strapping | adc | ADC1 Channel 0 |
| 11 | 39 | SVNGPIO39 | strapping | adc | ADC1 Channel 3 |
| 12 | 32 | IO32GPIO32 | safe | adc · touch | ADC1 Channel 4 / Touch 9 |
| 13 | 33 | IO33GPIO33 | safe | adc · touch | ADC1 Channel 5 / Touch 8 |
| 14 | 25 | IO25GPIO25 | safe | dac | 8-bit Digital-to-Analog Converter 1 |
| 15 | 26 | IO26GPIO26D0 | safe | dac | 8-bit Digital-to-Analog Converter 2 |
| 16 | 27 | IO27GPIO27 | safe | touch | Touch 7 / RTC-17 |
| 17 | 14 | TMSGPIO14 | strapping | touch · spi | HSPI SCK / Touch 6 |
| 18 | 12 | TDIGPIO12 | strapping | touch · spi | HSPI MISO / Touch 5 |
| 19 | 13 | TCKGPIO13 | strapping | touch · spi | HSPI MOSI / Touch 4 |
| 20 | 15 | TD0GPIO15 | strapping | touch | Boot-strap Pin / Touch 3 |
| 21 | 4 | IO4GPIO4 | safe | adc · touch | Touch 0 / ADC2 Channel 0 |
| 22 | 16 | IO16GPIO16RX2D4 | uart | uart | UART2 Receive |
| 23 | 17 | IO17GPIO17TX2D3 | uart | uart | UART2 Transmit |
| 24 | 0 | IO0GPIO0 | strapping | touch | Boot-mode Select / Touch 1 (keep HIGH to boot) |
| 25 | 34 | IO34GPIO34 | strapping | adc | ADC1 Channel 6 (input-only) |
| 26 | 35 | IO35GPIO35 | strapping | adc | ADC1 Channel 7 (input-only) |
| 27 | - | GND | ground | - | Ground connection |
| 28 | - | NC | safe | - | Not connected |
| 29 | - | NC | safe | - | Not connected |
| 30 | 9 | SD2GPIO9 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
| 31 | 11 | CMDGPIO11 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
| 32 | - | RST | control | - | Chip reset (active LOW) - the same net as the RST button |
| 33 | - | 3V33.3V | power | - | 3.3V power output from the on-board regulator |
| 34 | 10 | SD3GPIO10 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
| 35 | - | GND | ground | - | Ground connection |
| 36 | 8 | SD1GPIO8 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
| 37 | 6 | CLKGPIO6 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
| 38 | - | GND | ground | - | Ground connection |
| 39 | - | 5V5V0 | power | - | 5V from the USB connector - also the input when powering the board from here |
| 40 | 7 | SD0GPIO7 | strapping | - | Wired to the module's SPI flash - do NOT use, the board will crash or fail to boot |
Start with these
13 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
13 pins · 12 things to knowIO2 Bootstrapping pin (must be low or floating at reset); internal pull-down. Strapping
If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.
TXDGPIO1 Default UART0 TX pin for USB-serial programming and console. UART
Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console.
RXDGPIO3 Default UART0 RX pin for USB-serial programming (console input). UART
Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads.
IO5 Bootstrapping pin; internal pull-up; VSPI CS0 (default SPI chip-select); acts as FSPIWP (flash write-protect) on internal-flash variants. Strapping
Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.
SVPGPIO36 Input-only GPIO (no output); ADC1 channel 0, Hall sensor VP. Other
Cannot be used as output; only suitable for input (e.g., analog read).
SVNGPIO39IO35 Input-only GPIOs with ADC1 channels - no output driver Other
Cannot be used as output; only suitable for input.
- SVNInput-only GPIO (no output); ADC1 channel 3, Hall sensor VN.
- IO35Input-only GPIO (no output driver); ADC1 channel 7.
TMSGPIO14 JTAG mode select pin (TMS); also HSPI CLK and PWM-capable GPIO. JTAG
Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.
TDIGPIO12 Bootstrapping pin; JTAG TDI; sets flash voltage (VDD_SDIO); also HSPIQ (flash data line). Strapping
Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used.
TCKGPIO13 JTAG clock pin (TCK); also ADC2 channel 4 / Touch4 input. JTAG
Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.
TD0GPIO15 Bootstrapping pin; JTAG TDO; controls UART0 boot log output; also HSPICS0 (secondary SPI CS). Strapping
Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.
IO0 Bootstrapping pin (enter bootloader when low); internal pull-up. Strapping
Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.
IO34 Input-only GPIO (no output driver); ADC1 channel 6. Other
Cannot be used as output (no drive capability); only suitable for analog/digital input.
Only if you know the tricks
6 pins · 4 things to knowSD2GPIO9SD3GPIO10 SPI flash/PSRAM data lines SD2 and SD3 (flash HOLD and WP) Flash
Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.
- SD2Connected to SPI flash/PSRAM data 2 (SD2, flash HOLD).
- SD3Connected to SPI flash/PSRAM data 3 (SD3, flash WP).
CMDGPIO11 Connected to SPI flash command/CS (CMD/CS0). Flash
Used by internal flash (chip select/command); not available for general use.
SD1GPIO8SD0GPIO7 SPI flash data lines SD0 and SD1 Flash
Used for internal flash/PSRAM data; not available for general GPIO.
- SD1Connected to SPI flash data 1 (SD1).
- SD0Connected to SPI flash data 0 (SD0).
CLKGPIO6 Connected to SPI flash clock (SCK/CLK). Flash
Used for internal flash/PSRAM communication; not available for general GPIO.
Across 40 pins (2.54 mm pitch), the WEMOS D1 MINI ESP32 exposes 32 GPIO plus GND, 3V3 and 5V for power.
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, IO21, IO22, IO23, IO19 and 9 more are free of any such role - the safest first picks. 13 of the exposed pins carry boot-time or system duties on the ESP32 (IO2, TXD, RXD and 10 more).
Pinout notes 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.…
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: 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
// toggle GPIO21 - wire an LED and resistor to it
void setup() {
pinMode(21, OUTPUT);
}
void loop() {
digitalWrite(21, HIGH); delay(500);
digitalWrite(21, LOW); delay(500);
}[env:d1_mini32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32dev - or type it after board =.esp32:
board: esp32dev
variant: esp32
framework:
type: esp-idf
# blink - GPIO21
output:
- platform: gpio
pin: 21
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32dev (same ids as PlatformIO).esptool.py --chip esp32 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x1000 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Good 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.
Downloads
Free for non-commercial use, credit espboards.dev · License
Board illustration
The bare WEMOS D1 MINI ESP32 board drawn to scale at 39 × 31 mm, with no pin labels on it. Made for slide decks, wiring diagrams and project write-ups where a photo is too busy. Take the scalable SVG for print or editing, the high-resolution PNG to drop straight in, or the transparent PNG when you need it with no background behind it.
Pinout diagram
Every pin on both sides of the board with its functions, drawn by ESPboards from the ESP32 Series Datasheet v5.3 - the same sheet shown at the top of this page. The PNG is a high-resolution image for screens, the SVG is vector so it stays sharp at any size, and the PDF is laid out to print on A4 or Letter.
Yours to use, share and adapt for non-commercial work, as long as you credit espboards.dev - the full terms and ready-made credit lines are here.
Specifications
ESP32 · 39 × 31 mm · vs other ESP32 chips →Dimensions
About 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.
32 GPIO are broken out - more than most ESP32 boards, so the pin budget is rarely the constraint.
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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