NodeMCU-32S Development Board

Code name: NodeMCU_32S

NodeMCU-32S development board is based on esp32 microcontroller and uses xtensa architecture. This board has a maximum CPU frequency of 240 MHz and a flash size of 4MB.

⚡ Tech Specs 📌 Pinout 🔗 Useful Links 🗺️ Mappings 🛠️ Tools

About NodeMCU-32S

The NodeMCU-32S is a feature-rich development board based on the Espressif ESP32-WROOM-32 module. With integrated Wi-Fi 802.11 b/g/n and Bluetooth 4.2 (BR/EDR + BLE), it’s ready for IoT projects that demand robust wireless connectivity. 📡

Its breadboard-friendly form factor pairs with an on-board CP2102 USB-to-UART converter, so you can plug in, program, and prototype in seconds—no extra hardware required. 🔌

For convenient development, the board comes with an EN (reset) button 🔁 and a BOOT (IO0) button, making flashing firmware and entering download mode a breeze. 🚀

A built-in PCB antenna delivers stable RF performance without the need for external antennas, keeping your setup compact. 📶

Exposing 30+ versatile GPIOs that support ADC, DAC, PWM, I²C, SPI, UART, capacitive touch, and more, the NodeMCU-32S empowers you to interface with a wide range of sensors, displays, and actuators. ⚙️

🤔 Curious how the NodeMCU-32S stacks up against other ESP32 boards? Dive into our detailed comparison guide to choose the best fit for your next project.

Where to Buy

Starting from

8$ per unit

Amazon.com Ships worldwide

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Amazon.de Ships to EU

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AliExpress Best value

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Prices are subject to change. We earn from qualifying purchases as an Amazon Associate.

Technical Specifications

🛰️ Connectivity

WiFi 802.11 b/g/n (2.4 GHz)

Bluetooth 4.2

BLE 4.2

🧠 Microcontroller

Model esp32

Clock Speed 240 MHz

Flash Size 4MB

Architecture xtensa

✨ Features

40 digital IO pins
16 external interrupt pins
16 analog input pins
19 PWM pins

View Full Datasheet

NodeMCU-32S Dimensions

Width 22.86 mm

Length 48.26 mm

Pin Gap 2.54 mm

NodeMCU-32S Pinout

The NodeMCU-32S pinout gives you nearly every feature of the ESP32-WROOM-32 module in a breadboard-friendly format. Key power rails—VIN (5 V), 3V3, and multiple GND pins—let you power the board itself or feed external sensors and actuators with ease.

For serial communication the board breaks out RX0 and TX0 (UART0, connected to the on-board CP2102 for USB programming) plus an extra pair, RX2 (GPIO16) and TX2 (GPIO17), for a second hardware UART. Default I²C lines are SDA (GPIO21) and SCL (GPIO22), while the default VSPI port maps to MOSI (GPIO23), MISO (GPIO19), SCK (GPIO18), and CS (GPIO5). An alternate HSPI bus (GPIO12-15) is available when you need multiple SPI devices.

On the analog side, GPIO32 – GPIO39 expose ADC1 channels, and several ADC2 channels appear on GPIO0, GPIO2, GPIO4, GPIO12-15, and GPIO25-27 (ADC2 is not usable while Wi-Fi is running). Two 8-bit DAC outputs live on GPIO25 and GPIO26, perfect for audio or reference-voltage generation. Many of these pads double as capacitive-touch inputs for sleek, button-free interfaces.

Every GPIO supports PWM for LED dimming or motor control, and special-function pins such as EN (reset) and BOOT (IO0) make flashing easy. Take note of bootstrapping pins GPIO0, GPIO2, and GPIO15; keep them in the proper state (usually pulled HIGH) during reset to ensure normal startup.

With plentiful digital I/O, rich analog capabilities, and multiple high-speed buses, the NodeMCU-32S pinout delivers the versatility needed for everything from simple sensor nodes to complex connected gadgets—all while staying compact enough for quick prototyping.

✅ Safe Pins to Use

For general GPIO usage, these are the safest and most flexible choices:

🔹 LED_BUILTIN

🔹 IO21

🔹 IO22

🔹 IO23

🔹 IO19

🔹 IO18

🔹 IO32

🔹 IO33

🔹 IO25

🔹 IO26

🔹 IO27

Why Are These Pins Safe?

Not involved in bootstrapping → No impact on device boot mode or system startup
Not linked to flash memory or PSRAM → Won't interfere with storage or memory access
Not dedicated to USB or JTAG → Free for general use without affecting debugging
No special hardware connections → Freely assignable without internal conflicts

⚠️ Pins to Avoid or Use with Caution

Some pins are reserved for critical functions like bootstrapping, JTAG debugging, USB communication, and flash memory operations. Misusing these pins may lead to boot failures, programming issues, USB conflicts, or disruptions in flash storage.

Critical Pin Categories:

🛠️ Strapping Pins: Control boot behavior and flash voltage selection
🔗 JTAG Debugging Pins: Required for low-level debugging
🔌 USB Communication Pins: Used for USB Serial/JTAG communication
⚡ Flash Memory & SPI Pins: Connected to SPI flash memory and PSRAM
📡 UART Serial Communication Pins: Used for debugging and firmware uploads

PIN	Label	Reason	Function
IO3	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
IO1	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
IO5	GPIO5	Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.	🛠️ Strapping
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
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
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
IO0	GPIO0	Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.	🛠️ Strapping
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

NodeMCU-32S Useful Links

🔗 Datasheet

https://www.waveshare.com/wiki/NodeMCU-32S

🔗 ESP32 Datasheet

https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf

NodeMCU-32S Pin Mappings

This development board provides 40 digital IO pins, out of which 16 can be used as external interrupt pins , 16 as analog input pins and 19 pins have Pulse-Width Modulation (PWM) .

Pin	Function	ESP Pin	Input/Output	Description
1	LED_BUILTIN	GPIO2	output	On-board user LED (active-LOW)
2	IO3	GPIO3	input	UART0 RX (USB serial)
3	IO1	GPIO1	output	UART0 TX (USB serial)
4	IO21	GPIO21	bidirectional	I²C SDA
5	IO22	GPIO22	bidirectional	I²C SCL
6	IO5	GPIO5	bidirectional	VSPI CS / SS
7	IO23	GPIO23	bidirectional	VSPI MOSI
8	IO19	GPIO19	bidirectional	VSPI MISO
9	IO18	GPIO18	bidirectional	VSPI SCK
10	IO36	GPIO36	input	ADC1 Channel 0 (SVP)
11	IO39	GPIO39	input	ADC1 Channel 3 (SVN)
12	IO32	GPIO32	input	ADC1 Channel 4 / Touch 9
13	IO33	GPIO33	input	ADC1 Channel 5 / Touch 8
14	IO25	GPIO25	output	DAC1
15	IO26	GPIO26	output	DAC2
16	IO27	GPIO27	bidirectional	ADC2 Channel 7 / Touch 7
17	IO14	GPIO14	bidirectional	HSPI SCK / Touch 6
18	IO12	GPIO12	bidirectional	HSPI MISO / Touch 5
19	IO13	GPIO13	bidirectional	HSPI MOSI / Touch 4
20	IO15	GPIO15	bidirectional	MTDO / ADC2 Channel 3
21	IO4	GPIO4	bidirectional	Touch 0 / ADC2 Channel 0
22	IO16	GPIO16	bidirectional	UART2 RX / CLK_OUT
23	IO17	GPIO17	bidirectional	UART2 TX
24	IO0	GPIO0	bidirectional	BOOT-strap / Touch 1 (keep HIGH at reset)
25	IO34	GPIO34	input	ADC1 Channel 6
26	IO35	GPIO35	input	ADC1 Channel 7

Function Pin Function

ESP Pin Pin on ESP32

I/O Input/Output Pin

Description Pin Description

NodeMCU-32S Pins Mapping Arduino IDE

Below you can find the NodeMCU-32S pinout. This development board provides 40 digital IO pins, out of which 16 can be used as external interrupt pins, 16 as analog input pins and 19 pins have Pulse-Width Modulation (PWM).

Pin	Analog	Touch	PWM	Other
0	A11	T1		KEY_BUILTIN
1			PWM	TX
2	A12	T2	PWM	LED_BUILTIN
3			PWM	RX
4	A10	T0	PWM
5			PWM	SS
12	A15	T5	PWM
13	A14	T4	PWM
14	A16	T6	PWM
15	A13	T3	PWM
18			PWM	SCK
19			PWM	MISO
21			PWM	SDA
22			PWM	SCL
23			PWM	MOSI
25	A18		PWM	DAC1
26	A19		PWM	DAC2
27	A17	T7	PWM
32	A4	T9	PWM
33	A5	T8	PWM
34	A6
35	A7
36	A0
39	A3

Analog Analog input pins

Touch Touch pins

Function Function pins

RX / TX Receive/Transmit

LED_BUILTIN Built-in LED

PWM Pulse-Width Modulation

Default Tools

Bootloader tool	esptool_py
Uploader tool	esptool_py
Network uploader tool	esp_ota
Bootloader address	0x1000
Flash mode	dio
Boot mode	dio
Maximum upload size	1280 Kb (1310720 B)
Maximum data size	320 Kb (327680 B)

The NodeMCU-32S development board by default uses esptool_py uploader tool, esp_ota network uploader tool for Over-the-air (OTA) uploads and esptool_py bootloader tool. The bootloader starts at address "0x1000". Flash mode and boot mode for NodeMCU-32S development board by default is dio and dio respectively.