HiLetgo ESP-WROOM-32 Development Board

by Generic

ESP32 development board with 2.4GHz WiFi, Bluetooth, dual cores, and Arduino IDE compatibility.

Micro-USB

Buy on Amazon · $8.99 More sellers Pinout

HiLetgo ESP-WROOM-32 Development Board board

ESP32

MCU

240MHz

clock

4MB

flash

520KB

SRAM

32· 16 ADC

GPIO

BLE 4.2+ WiFi

radio

Pinout

33 pins

View:

HiLetgo ESP-WROOM-32 Development Board pinout diagram

Pin	GPIO	Labels	Status	Capabilities	Notes
1	36	IO36GPIO36	strapping	adc	ADC1_CH0, GPIO36
2	39	IO39GPIO39	strapping	adc	ADC1_CH3, GPIO39
3	34	IO34GPIO34	strapping	adc	ADC1_CH6, GPIO34
4	35	IO35GPIO35	strapping	adc	ADC1_CH7, GPIO35
5	32	IO32GPIO32	safe	adc	ADC1_CH4, GPIO32
6	33	IO33GPIO33	safe	adc	ADC1_CH5, GPIO33
7	25	IO25GPIO25	safe	adc · dac	DAC1, ADC2_CH8, GPIO25
8	26	IO26GPIO26	safe	adc · dac	DAC2, ADC2_CH9, GPIO26
9	27	IO27GPIO27	safe	adc	ADC2_CH7, GPIO27
10	14	IO14GPIO14	strapping	adc	ADC2_CH6, GPIO14
11	12	IO12GPIO12	strapping	adc	ADC2_CH5, GPIO12
12	-	GND	ground	-	Ground
13	13	IO13GPIO13	strapping	adc	ADC2_CH4, GPIO13
14	9	IO9GPIO9	strapping	-	SD_DATA2, GPIO9
15	10	IO10GPIO10	strapping	-	SD_DATA3, GPIO10
16	11	IO11GPIO11	strapping	-	SD_CMD, GPIO11
17	6	IO6GPIO6	strapping	-	SD_CLK, GPIO6
18	7	IO7GPIO7	strapping	-	SD_DATA0, GPIO7
19	8	IO8GPIO8	strapping	-	SD_DATA1, GPIO8
20	15	IO15GPIO15	strapping	adc	ADC2_CH3, GPIO15
21	2	IO2GPIO2	strapping	adc	ADC2_CH2, GPIO2, LED
22	0	IO0GPIO0	strapping	adc	ADC2_CH1, GPIO0, BOOT
23	4	IO4GPIO4	strapping	adc	ADC2_CH0, GPIO4
24	16	IO16GPIO16	strapping	-	GPIO16
25	17	IO17GPIO17	strapping	-	GPIO17
26	5	IO5GPIO5	strapping	-	GPIO5
27	18	IO18GPIO18	safe	-	GPIO18
28	19	IO19GPIO19	safe	-	GPIO19
29	21	IO21GPIO21	safe	-	GPIO21
30	3	RXGPIO3	uart	uart	UART0 Receive
31	1	TXGPIO1	uart	uart	UART0 Transmit
32	22	IO22GPIO22	safe	-	GPIO22
33	23	IO23GPIO23	safe	-	GPIO23

Start with these

10 pins with no boot or system involvement

IO32GPIO32IO33GPIO33IO25GPIO25IO26GPIO26IO27GPIO27IO18GPIO18IO19GPIO19IO21GPIO21IO22GPIO22IO23GPIO23

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
IO36	GPIO36 (SENSOR_VP)	Cannot be used as output; only suitable for input (e.g., analog read).	Other
IO39	GPIO39 (SENSOR_VN)	Cannot be used as output; only suitable for input.	Other
IO34	GPIO34	Cannot be used as output (no drive capability); only suitable for analog/digital input.	Other
IO35	GPIO35	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
IO2	GPIO2	If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.	Strapping
IO0	GPIO0	Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.	Strapping
IO4	GPIO4	Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).	Strapping
IO5	GPIO5	Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.	Strapping

Only if you know the tricks

wired to flash or USB - expect a fight

Pin	Label	What to know	Role
IO9	GPIO9 (Flash SD2)	Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.	Flash
IO10	GPIO10 (Flash SD3)	Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.	Flash
IO11	GPIO11 (Flash CMD)	Used by internal flash (chip select/command); not available for general use.	Flash
IO6	GPIO6 (Flash SCK)	Used for internal flash/PSRAM communication; not available for general GPIO.	Flash
IO7	GPIO7 (Flash SD0)	Used for internal flash/PSRAM data; not available for general GPIO.	Flash
IO8	GPIO8 (Flash SD1)	Used for internal flash/PSRAM data; not available for general GPIO.	Flash
IO16	GPIO16	Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.	Flash
IO17	GPIO17	Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.	Flash
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
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

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 The HiLetgo ESP-WROOM-32 Development Board breaks out 33 pins in total: 32 GPIO for your project, with GND handling power. For peripherals, TX / RX on GPIO1…

The HiLetgo ESP-WROOM-32 Development Board breaks out 33 pins in total: 32 GPIO for your project, with GND handling power.

For peripherals, TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.

On the analog side there are 16 ADC-capable pins for sensors and battery monitoring and 2 true DAC outputs.

If you want zero surprises, IO32, IO33, IO25, IO26 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 (IO36, IO39, IO34 and 9 more).

Getting started

flash your first firmware in ~2 minutes

Tool:

Connect over USB

Serial chip: CP2102. Not detected? Hold BOOT while plugging in.

Flash with your tool

Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.

Verify it runs

The blink example uses GPIO32 - swap for your board's LED pin if different.

Tools → Board settings Copy

Board:            Esp32 Dev
Flash Size:       4MB · DIO
Upload Speed:     921600

// blink
pinMode(32, OUTPUT);
digitalWrite(32, LOW);   // on (often inverted)

platformio.ini Copy

[env:hiletgo-esp-wroom-32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600

device.yaml Copy

esp32:
  board: esp32dev
  variant: esp32
  framework:
    type: esp-idf

# blink - GPIO32
output:
  - platform: gpio
    pin: 32
    id: led_out
light:
  - platform: binary
    name: "LED"
    output: led_out

shell Copy

esptool.py --chip esp32 --port /dev/ttyACM0 \
  write_flash 0x0 firmware.bin

Build details: sketch space 1310720 B · data 327680 B · DIO

Good to know

board-specific quirks worth 60 seconds

HiLetgo ESP-WROOM-32 Compatibility Arduino IDE Setup Board Selection: Use "Node32" for Bluetooth functionality, or "ESP32 Dev Module" for standard operation Built-in LED: Connected to GPIO2 - use digitalWrite(2, HIGH) to control Upload Speed: Supports high-speed uploads up to 921,600 baud Technical Specifications Based on ESP32-WROOM-32 module with TSMC 40nm ultra-low power technology. Supports AP, STA, and AP+STA…

HiLetgo ESP-WROOM-32 Compatibility

Arduino IDE Setup

Board Selection: Use "Node32" for Bluetooth functionality, or "ESP32 Dev Module" for standard operation
Built-in LED: Connected to GPIO2 - use digitalWrite(2, HIGH) to control
Upload Speed: Supports high-speed uploads up to 921,600 baud

Technical Specifications

Based on ESP32-WROOM-32 module with TSMC 40nm ultra-low power technology. Supports AP, STA, and AP+STA modes for WiFi connectivity.

Getting Started

Connect via Micro-USB, install ESP32 board support in Arduino IDE, and start developing IoT applications with built-in WiFi and Bluetooth capabilities.

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

32 · 16

UART · I²C · SPI

3 · 2 · 4

PWM

16 channels

Power

USB

Micro-USB

Serial

CP2102

Boot address

0x1000

Flashing

Upload · OTA

esptool_py · esp_ota

Flash · Boot mode

DIO · DIO

Sketch · Data

1.25 MB · 320 KB

The HiLetgo ESP-WROOM-32 Development Board 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.

Expect to pay about $8.99 - 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 EN/Boot buttons.

Where to buy

prices are typical street prices

HiLetgo ESP-WROOM-32 Development Board

$8.99per unit, typical

AMZAmazon.com↗

As an Amazon Associate, ESPboards earns from qualifying purchases.

Resources

ESP32 datasheet espressif.com↗ HiLetgo ESP-WROOM-32 Fritzing forum.fritzing.org↗HiLetgo ESP-32 pinouts, specs and examples (Cirkit Designer) docs.cirkitdesigner.com↗HiLetgo ESP32 Dev Kit (ThingsBoard device library) thingsboard.io↗

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