ESP32-MINI-1

module
Espressif Systems Datasheet ↗

Built around the single-core/dual-core ESP32-U4WDH SiP with 4 MB in-package flash, ESP32-MINI-1 (13.2×19.0 mm PCB antenna) and ESP32-MINI-1U (13.2×13.5 mm U.FL) deliver classic ESP32 Wi-Fi 4 + Classic BT / BLE 4.2 in a 55-pad 0.8 mm LGA package. Because U4WDH bonds internal flash to GPIO16/17, both IO9 and IO10 (Pins 25–26) AND input-only I37/I38 (Pins 5–6) are freely available alongside 2× DACs.

Silicon IC: ESP32 Boards / Modules: ESP32-WROOM-32E ESP32-WROVER-E Also known as: ESP32-MINI-1U ESP32-MINI-1-N4 ESP32-MINI-1U-N4 ESP32-MINI-1-H4
ESPRESSIF ESP32-MINI-1 1 GND GND GND 2 GND GND GND 3 3V3 ! 3V3 3V3 4 I36 ! GPIO36 ADC1_CH0 GPIO36 ADC1_CH0 5 I37 ! GPIO37 ADC1_CH1 GPIO37 ADC1_CH1 6 I38 ! GPIO38 ADC1_CH2 GPIO38 ADC1_CH2 7 I39 ! GPIO39 ADC1_CH3 GPIO39 ADC1_CH3 8 EN ! CHIP_PU CHIP_PU 9 I34 ! GPIO34 ADC1_CH6 GPIO34 ADC1_CH6 10 I35 ! GPIO35 ADC1_CH7 GPIO35 ADC1_CH7 11 IO32 GPIO32 ADC1_CH4 System Clock +2 GPIO32 ADC1_CH4 TOUCH9 XTAL_32K_P 12 IO33 GPIO33 ADC1_CH5 System Clock +2 GPIO33 ADC1_CH5 TOUCH8 XTAL_32K_N 13 IO25 ! GPIO25 ADC2_CH8 DAC_1 GPIO25 ADC2_CH8 DAC_1 14 IO26 ! GPIO26 ADC2_CH9 DAC_2 GPIO26 ADC2_CH9 DAC_2 15 IO27 ! GPIO27 ADC2_CH7 TOUCH7 GPIO27 ADC2_CH7 TOUCH7 16 IO14 ! GPIO14 HSPICLK ADC System Debug +3 GPIO14 ADC2_CH6 TOUCH6 HSPICLK MTMS 17 IO12 ! GPIO12 HSPIQ ADC System Debug +3 GPIO12 ADC2_CH5 TOUCH5 HSPIQ MTDI 18 IO13 ! GPIO13 HSPID ADC System Debug +3 GPIO13 ADC2_CH4 TOUCH4 HSPID MTCK 19 IO15 ! GPIO15 HSPICS0 ADC System Debug +3 GPIO15 ADC2_CH3 TOUCH3 HSPICS0 MTDO 20 IO2 ! GPIO2 ADC2_CH2 TOUCH2 GPIO2 ADC2_CH2 TOUCH2 21 IO0 ! GPIO0 ADC2_CH1 TOUCH1 GPIO0 ADC2_CH1 TOUCH1 22 IO4 ! GPIO4 ADC2_CH0 TOUCH0 GPIO4 ADC2_CH0 TOUCH0 23 NC 24 NC 25 IO9 GPIO9 SPIHD GPIO9 SPIHD 26 IO10 GPIO10 SPIWP GPIO10 SPIWP 27 GND GND GND 28 NC 29 IO5 ! GPIO5 VSPICS0 GPIO5 VSPICS0 30 IO18 GPIO18 VSPICLK GPIO18 VSPICLK 31 IO23 GPIO23 VSPID GPIO23 VSPID 32 IO19 GPIO19 VSPIQ U0CTS GPIO19 VSPIQ U0CTS 33 IO22 GPIO22 I2C0_SCL U0RTS GPIO22 I2C0_SCL U0RTS 34 IO21 GPIO21 I2C0_SDA GPIO21 I2C0_SDA 35 RXD0 ! GPIO3 U0RXD GPIO3 U0RXD 36 TXD0 ! GPIO1 U0TXD GPIO1 U0TXD 37 NC 38-55 GND GND GND

Onboard Peripherals & Internal Signals

In-Package 4 MB Flash (ESP32-U4WDH) QSPI
Chip Pad: GPIO16
Bonded internally to GPIO6/7/8/11 and GPIO16/17 (IO9 and IO10 remain free!)

Internal 3.3V flash inside ESP32-U4WDH.

Pin Assignment Planner

Add the peripherals you need and plan the pin assignments

Full Pin Reference (38 Pins)

Pin # Label Type Functions Warnings & Notes
1 GND ground GND
Module system ground (0V)
2 GND ground GND
Module system ground (0V)
3 3V3 power 3V3
[CAUTION] 3.0V–3.6V supply only (>=500 mA current capability + 10 µF & 0.1 µF decoupling)
Wi-Fi TX bursts draw high peak current. Exceeding 3.6V permanently damages the SoC and onboard flash.
Main 3.3V module power supply input (3.0V–3.6V; >=500 mA regulator recommended)
4 I36 GPIO36 mixed GPIO36 ADC1_CH0
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO36 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO36 (no output driver, no internal pull resistors, 3.3V max)
5 I37 GPIO37 mixed GPIO37 ADC1_CH1
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO37 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO37 (no output driver, no internal pull resistors, 3.3V max)
6 I38 GPIO38 mixed GPIO38 ADC1_CH2
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO38 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO38 (no output driver, no internal pull resistors, 3.3V max)
7 I39 GPIO39 mixed GPIO39 ADC1_CH3
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO39 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO39 (no output driver, no internal pull resistors, 3.3V max)
8 EN CHIP_PU reset CHIP_PU
[CAUTION] Active-HIGH chip enable / reset — never leave floating
High enables ESP32; Low powers off the chip. Connect an external 10 kΩ pull-up to 3.3V and 1 µF delay capacitor to GND.
Active-HIGH chip enable / reset input (EN / CHIP_PU)
9 I34 GPIO34 mixed GPIO34 ADC1_CH6
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO34 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO34 (no output driver, no internal pull resistors, 3.3V max)
10 I35 GPIO35 mixed GPIO35 ADC1_CH7
[CAUTION] Input-only pin — NO output driver and NO internal pull-up/pull-down resistors
GPIO35 (RTC/ADC1 domain) can only be used as a digital or analog input. Provide an external pull-up or pull-down resistor if driven by an open-drain or mechanical switch.
Input-only RTC/ADC1 GPIO35 (no output driver, no internal pull resistors, 3.3V max)
11 IO32 GPIO32 mixed GPIO32 ADC1_CH4 TOUCH9 XTAL_32K_P
General-purpose 3.3V GPIO32 (NOT 5V tolerant)
12 IO33 GPIO33 mixed GPIO33 ADC1_CH5 TOUCH8 XTAL_32K_N
General-purpose 3.3V GPIO33 (NOT 5V tolerant)
13 IO25 GPIO25 mixed GPIO25 ADC2_CH8 DAC_1
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO25 (NOT 5V tolerant)
14 IO26 GPIO26 mixed GPIO26 ADC2_CH9 DAC_2
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO26 (NOT 5V tolerant)
15 IO27 GPIO27 mixed GPIO27 ADC2_CH7 TOUCH7
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO27 (NOT 5V tolerant)
16 IO14 GPIO14 mixed GPIO14 ADC2_CH6 TOUCH6 HSPICLK MTMS
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO14 (NOT 5V tolerant)
17 IO12 GPIO12 mixed GPIO12 ADC2_CH5 TOUCH5 HSPIQ MTDI
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
[DANGER] VDD_SDIO flash voltage strap (weak pull-down: LOW=3.3V, HIGH=1.8V — boot failure risk!)
Pulling GPIO12 (MTDI) HIGH during reset switches internal flash power VDD_SDIO to 1.8V, causing boot brownout/loops on 3.3V flash modules (WROOM-32E, WROVER-E) unless overridden via eFuse.
General-purpose 3.3V GPIO12 (NOT 5V tolerant)
18 IO13 GPIO13 mixed GPIO13 ADC2_CH4 TOUCH4 HSPID MTCK
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO13 (NOT 5V tolerant)
19 IO15 GPIO15 mixed GPIO15 ADC2_CH3 TOUCH3 HSPICS0 MTDO
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
[INFO] ROM boot log strapping pin (weak pull-up: HIGH=U0TXD boot log enabled, LOW=silent)
Controls early ROM bootloader messages on U0TXD (GPIO1) during reset.
General-purpose 3.3V GPIO15 (NOT 5V tolerant)
20 IO2 GPIO2 mixed GPIO2 ADC2_CH2 TOUCH2
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
[CAUTION] Download boot strapping pin (weak pull-down: must be LOW or floating to flash)
Must be LOW or left floating when GPIO0 is pulled LOW to enter UART Download Boot.
General-purpose 3.3V GPIO2 (NOT 5V tolerant)
21 IO0 GPIO0 mixed GPIO0 ADC2_CH1 TOUCH1
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
[CAUTION] Boot mode strapping pin (weak pull-up: HIGH=SPI Flash Boot, LOW=Download Boot)
Sampled at reset. Holding GPIO0 LOW with GPIO2 LOW enters UART0 Download Boot.
General-purpose 3.3V GPIO0 (NOT 5V tolerant)
22 IO4 GPIO4 mixed GPIO4 ADC2_CH0 TOUCH0
[CAUTION] ADC2 channel unavailable while Wi-Fi radio is active
The Wi-Fi transceiver shares the SAR ADC2 controller. Use ADC1 (GPIO32–GPIO39) whenever Wi-Fi and analog reads run concurrently.
General-purpose 3.3V GPIO4 (NOT 5V tolerant)
23 NC nc —
No internal connection — leave floating on host PCB
24 NC nc —
No internal connection — leave floating on host PCB
25 IO9 GPIO9 digital GPIO9 SPIHD
General-purpose 3.3V GPIO9 (NOT 5V tolerant)
26 IO10 GPIO10 digital GPIO10 SPIWP
General-purpose 3.3V GPIO10 (NOT 5V tolerant)
27 GND ground GND
Module system ground (0V)
28 NC nc —
No internal connection — leave floating on host PCB
29 IO5 GPIO5 digital GPIO5 VSPICS0
[INFO] SDIO Slave timing strapping pin (internal weak pull-up)
Sampled at reset only if SDIO Slave mode is used; safe for normal general-purpose output.
General-purpose 3.3V GPIO5 (NOT 5V tolerant)
30 IO18 GPIO18 digital GPIO18 VSPICLK
General-purpose 3.3V GPIO18 (NOT 5V tolerant)
31 IO23 GPIO23 digital GPIO23 VSPID
General-purpose 3.3V GPIO23 (NOT 5V tolerant)
32 IO19 GPIO19 digital GPIO19 VSPIQ U0CTS
General-purpose 3.3V GPIO19 (NOT 5V tolerant)
33 IO22 GPIO22 digital GPIO22 I2C0_SCL U0RTS
General-purpose 3.3V GPIO22 (NOT 5V tolerant)
34 IO21 GPIO21 digital GPIO21 I2C0_SDA
General-purpose 3.3V GPIO21 (NOT 5V tolerant)
35 RXD0 GPIO3 digital GPIO3 U0RXD
[INFO] Default UART0 console & bootloader RX pin
Outputs/receives ROM bootloader traffic at reset unless silenced via GPIO15.
General-purpose 3.3V GPIO3 (NOT 5V tolerant)
36 TXD0 GPIO1 digital GPIO1 U0TXD
[INFO] Default UART0 console & bootloader TX pin
Outputs/receives ROM bootloader traffic at reset unless silenced via GPIO15.
General-purpose 3.3V GPIO1 (NOT 5V tolerant)
37 NC nc —
No internal connection — leave floating on host PCB
38-55 GND ground GND
Underside 18-pad thermal & RF ground array (Pads 38–55; connect to host GND)