ESP32 38-Pin DevKit (Generic Clone)

Universal guide for identifying and using generic 38-pin ESP32 DevKit clones (NodeMCU-32S style).

Micro-USB
ESP32 38-Pin DevKit (Generic Clone) board
55 × 28 mm
ESP32
MCU
240MHz
clock
4MB
flash
520KB
SRAM
32· 16 ADC
GPIO
BLE 4.2+ WiFi
radio

Pinout

38 pins
View:
ESP32 38-Pin DevKit (Generic Clone) pinout diagram
PinGPIOLabelsStatusCapabilitiesNotes
1-3V33.3Vpower-3.3V regulated output (~600mA max)
2-ENcontrol-Chip enable / reset (active LOW)
336VPGPIO36A0strappingadcSENSOR_VP, ADC1_CH0, input only, no pull resistors
439VNGPIO39A3strappingadcSENSOR_VN, ADC1_CH3, input only, no pull resistors
534D34GPIO34A6strappingadcADC1_CH6, input only, no pull resistors
635D35GPIO35A7strappingadcADC1_CH7, input only, no pull resistors
732D32GPIO32A4safeadc · touchADC1_CH4, Touch9
833D33GPIO33A5safeadc · touchADC1_CH5, Touch8
925D25GPIO25A18safeadc · dacDAC1, ADC2_CH8
1026D26GPIO26A19safeadc · dacDAC2, ADC2_CH9
1127D27GPIO27A17safeadc · touchADC2_CH7, Touch7
1214D14GPIO14A16strappingadc · touch · spiADC2_CH6, Touch6, HSPI_CLK
1312D12GPIO12A15strappingadc · touch · spiADC2_CH5, Touch5, HSPI_MISO, Strapping pin (flash voltage)
14-GNDground-Ground
1513D13GPIO13A14strappingadc · touch · spiADC2_CH4, Touch4, HSPI_MOSI
169SD2GPIO9strapping-Internal SPI flash (SD_DATA2) - not usable
1710SD3GPIO10strapping-Internal SPI flash (SD_DATA3) - not usable
1811CMDGPIO11strapping-Internal SPI flash (SD_CMD) - not usable
19-VIN5Vpower-5V input to onboard regulator
20-GNDground-Ground
2123D23GPIO23safespiVSPI_MOSI
2222D22GPIO22safei2cI2C_SCL (default)
231TX0GPIO1uartuartUART0 TX (USB serial)
243RX0GPIO3uartuartUART0 RX (USB serial)
2521D21GPIO21safei2cI2C_SDA (default)
26-GNDground-Ground
2719D19GPIO19safespiVSPI_MISO
2818D18GPIO18safespiVSPI_CLK
295D5GPIO5strappingspiVSPI_CS, Strapping pin
3017TX2GPIO17strappinguartUART2 TX
3116RX2GPIO16strappinguartUART2 RX
324D4GPIO4A10strappingadc · touchADC2_CH0, Touch0
330D0GPIO0A11strappingadc · touchADC2_CH1, Touch1, Boot button (strapping pin)
342D2GPIO2A12strappingadc · touchADC2_CH2, Touch2, on-board LED, Strapping pin
3515D15GPIO15A13strappingadc · touch · spiADC2_CH3, Touch3, HSPI_CS, Strapping pin
368SD1GPIO8strapping-Internal SPI flash (SD_DATA1) - not usable
377SD0GPIO7strapping-Internal SPI flash (SD_DATA0) - not usable
386CLKGPIO6strapping-Internal SPI flash (SD_CLK) - not usable

Start with these

10 pins with no boot or system involvement
D32GPIO32D33GPIO33D25GPIO25D26GPIO26D27GPIO27D23GPIO23D22GPIO22D21GPIO21D19GPIO19D18GPIO18

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
PinLabelWhat to knowRole
VPGPIO36 (SENSOR_VP)Cannot be used as output; only suitable for input (e.g., analog read).Other
VNGPIO39 (SENSOR_VN)Cannot be used as output; only suitable for input.Other
D34GPIO34Cannot be used as output (no drive capability); only suitable for analog/digital input.Other
D35GPIO35Cannot be used as output; only suitable for input.Other
D14MTMS (GPIO14)Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.Other
D12MTDI (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
D13MTCK (GPIO13)Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.Other
D5GPIO5Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.Strapping
D4GPIO4Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).Strapping
D0GPIO0Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.Strapping
D2GPIO2If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.Strapping
D15MTDO (GPIO15)Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.Strapping

Only if you know the tricks

wired to flash or USB - expect a fight
PinLabelWhat to knowRole
SD2GPIO9 (Flash SD2)Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.Flash
SD3GPIO10 (Flash SD3)Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.Flash
CMDGPIO11 (Flash CMD)Used by internal flash (chip select/command); not available for general use.Flash
TX0U0TXD (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
RX0U0RXD (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
TX2GPIO17Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.Flash
RX2GPIO16Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.Flash
SD1GPIO8 (Flash SD1)Used for internal flash/PSRAM data; not available for general GPIO.Flash
SD0GPIO7 (Flash SD0)Used for internal flash/PSRAM data; not available for general GPIO.Flash
CLKGPIO6 (Flash SCK)Used for internal flash/PSRAM communication; not available for general GPIO.Flash
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 ESP32 38-Pin DevKit (Generic Clone) breaks out 38 pins in total: 32 GPIO for your project, with 3V3 , GND and VIN handling power. On the analog side there…

The ESP32 38-Pin DevKit (Generic Clone) breaks out 38 pins in total: 32 GPIO for your project, with 3V3, GND and VIN handling power.

On the analog side there are 16 ADC-capable pins for sensors and battery monitoring, 10 capacitive-touch inputs and 2 true DAC outputs.

If you want zero surprises, D32, D33, D25, D26 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 (VP, VN, D34 and 9 more).


Universal 38-Pin Layout (NodeMCU-32S Style)

This pinout matches most 38-pin ESP32 development boards, including NodeMCU-32S and wider ESP32 DevKit clones.

Critical Boot Pins (Strapping Pins):

  • GPIO0 - Boot mode: HIGH = normal boot, LOW = download/flash mode
  • GPIO2 - Must be LOW or floating during boot (has onboard LED)
  • GPIO12 - Flash voltage: LOW = 3.3V (default), HIGH = 1.8V
  • GPIO15 - Debug output: LOW = normal (HIGH can cause boot failure)

Power

  • VIN: 5V input (powers regulator)
  • USB: 5V Micro-USB
  • 3V3 Out: ~600mA max
  • GPIO: 40mA/pin max

Serial

  • UART0: TX=GPIO1, RX=GPIO3
    USB programming
  • UART1: TX=GPIO10, RX=GPIO9
    Flash pins - avoid
  • UART2: TX=GPIO17, RX=GPIO16
    Available for sensors

I2C & SPI

  • I2C: SDA=GPIO21, SCL=GPIO22
    Software configurable
  • VSPI: MOSI=23, MISO=19, CLK=18, CS=5
  • HSPI: MOSI=13, MISO=12, CLK=14, CS=15

Analog & Touch Capabilities

ADC1 (WiFi-safe): GPIO32-39
Use these when WiFi is active
ADC2: GPIO0, 2, 4, 12-15, 25-27
Not reliable with WiFi
DAC: GPIO25 (DAC1), GPIO26 (DAC2)
8-bit digital-to-analog
Touch Sensors: Multiple GPIOs
No external components needed

Do NOT Use These Pins:

  • GPIO6-11: Connected to internal SPI flash - will cause boot failure
  • These pins are exposed on 38-pin boards but should never be used in your projects

Pro Tips:

  • Always use ADC1 channels (GPIO32-39) if WiFi is active
  • Never use GPIO6-11 - they're connected to flash memory
  • GPIO34-39 are input-only (no internal pull-up/down resistors)
  • Use external pull-up resistors on I2C lines (4.7kΩ typical)
  • Most 38-pin boards have an onboard LED on GPIO2
  • VIN pin allows powering the board from external 5V without USB

Getting started

flash your first firmware in ~2 minutes
Tool:
1
Connect over USB
Serial chip: CH340C / CH9102F / CP2102. Not detected? Hold BOOT while plugging in.
2
Flash with your tool
Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.
3
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:esp32-38pin-devkit-generic]
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

Specifications

ESP32 · 55 × 28 mm
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
CH340C / CH9102F / CP2102
Boot address
0x1000
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
1.25 MB · 320 KB
28 mm55 mm
55 × 28 mm
The ESP32 38-Pin DevKit (Generic Clone) 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 $4.00 - 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 EN/Boot buttons.


The ESP32 38-Pin DevKit is a wider variant of the ESP32 development board commonly found on AliExpress, eBay, and Amazon. These boards typically have "NodeMCU-32S" or "ESP32-WROOM-32" silkscreen labels and offer more exposed GPIO pins compared to the 30-pin variant.

How to Identify Which Board You Have

1. Check the USB-to-Serial Chip
Look near the USB port for a square or rectangle IC with one of these labels:
  • CH340C / CH340G → Most common on cheap clones. Rectangle chip.
  • {% image "images/ch340c.png", "CH340C on ESP32 30pin Development Board", [500], "auto", "rounded-lg my-4", "max-width: 500px; width: 100%; height: auto;", true, true %}
  • CP2102 → Common on mid-range boards. Square chip.
  • {% image "images/cp2102-nodemcu-32s.png", "CP2102 on ESP32 30pin Development Board", [500], "auto", "rounded-lg my-4", "max-width: 500px; width: 100%; height: auto;", true, true %}
  • CH9102F → Newer chip, similar to CP2102. Square chip.
  • {% image "images/cp2102-vs-ch9102.png", "CP2102 vs CH9102 on ESP32 30pin Development Board", [500], "auto", "rounded-lg my-4", "max-width: 500px; width: 100%; height: auto;", true, true %}
  • FT232RL → Less common but still found. Rectangle chip.

If you want to know more about USB-to-Serial chips, check out this detailed guide.

2. Count the Pins

38-pin boards are wider "NodeMCU-32S" style boards with 19 pins per side.

If you have 30 pins, check out the 30-pin variant guide instead.

3. Check the Power Regulator
  • AMS1117 → Older clones (gets hot under load)
    • Usually comes in a larger SOT-223 package with a flat metal tab (heatsinkable)
    • Often has "AMS1117" or "1117/3.3" printed directly on the chip
    • If you see a chunky 3-lead component with a metal tab near the USB port, it's likely AMS1117
    {% image "images/ams1117.png", "AMS1117 Voltage Regulator on ESP32 30pin Development Board", [500], "auto", "rounded-lg my-4", "max-width: 500px; width: 100%; height: auto;", true, true %}
  • ME6211 / HT7333 → Newer low-dropout regulators (better efficiency)
    • Typically comes in small SOT-89 or SOT-23 packages (much smaller than SOT-223)
    • If it's a tiny 3-pin SMD component next to the input capacitors, it's likely HT7333
    • May have short marking codes that are harder to read

Tip: Some boards print the regulator type on the silkscreen (check the board's underside or near the regulator for labels like "AMS1117" or "HT7333").

4. Look for Common Labels
Many 38-pin boards are labeled as:
  • NodeMCU-32S → Very common CP2102-based boards
  • ESP32 DevKit V1 → Generic label, various USB chips
  • ESP-WROOM-32 → Refers to the WiFi module, not the board itself

Key Advantages Over 30-Pin Boards

  • More GPIOs exposed: 38 pins vs 30 pins means access to GPIO6-11 (though still not recommended for general use)
  • VIN pin exposed: Can power from external 5V source without USB
  • Better breadboard compatibility: Wider spacing works better with some breadboards
  • More ground pins: Better for power distribution in complex projects

Important Notes

  • 38 pins total → More GPIOs than 30-pin variant, but still avoid GPIO6-11 (flash pins)
  • Some boards label ADC pins as VP, VN, SVP, SVN instead of GPIO numbers
  • Driver installation required for CH340 chips (automatic on most modern systems)
  • Strapping pins (GPIO0, GPIO2, GPIO12, GPIO15) must be in correct state during boot
  • Wider board requires more breadboard space (may not fit standard 400-point breadboards)
Despite the variations, these boards are excellent for complex projects that need more GPIO pins and external power options. They work perfectly with Arduino IDE, PlatformIO, and ESP-IDF once you identify which USB driver you need.

Where to buy

prices are typical street prices
ESP32 38-Pin DevKit (Generic Clone)
ESP32 38-Pin DevKit (Generic Clone)
$4.00per unit, typical
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Resources

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