ESP32-WROOM
Compact Wi-Fi and Bluetooth module based on the ESP32-D0WDQ6 chip, suitable for integration into various embedded systems.
ESP32-WROOM Pinout
35 pins
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 36 | SENSOR_VPGPIO36 | strapping | adc | ADC1_CH0, RTC_GPIO0 |
| 2 | 39 | SENSOR_VNGPIO39 | strapping | adc | ADC1_CH3, RTC_GPIO3 |
| 3 | 34 | IO34GPIO34 | strapping | adc | ADC1_CH6, RTC_GPIO4 |
| 4 | 35 | IO35GPIO35 | strapping | adc | ADC1_CH7, RTC_GPIO5 |
| 5 | 32 | IO32GPIO32 | safe | adc · touch | XTAL_32K_P (32.768 kHz crystal oscillator input), ADC1_CH4, TOUCH9, RTC_GPIO9 |
| 6 | 33 | IO33GPIO33 | safe | adc · touch | XTAL_32K_N (32.768 kHz crystal oscillator output), ADC1_CH5, TOUCH8, RTC_GPIO8 |
| 7 | 25 | IO25GPIO25 | safe | adc · dac | DAC_1, ADC2_CH8, RTC_GPIO6, EMAC_RXD0 |
| 8 | 26 | IO26GPIO26 | safe | adc · dac | DAC_2, ADC2_CH9, RTC_GPIO7, EMAC_RXD1 |
| 9 | 27 | IO27GPIO27 | safe | adc · touch | ADC2_CH7, TOUCH7, RTC_GPIO17, EMAC_RX_DV |
| 10 | 14 | IO14GPIO14 | strapping | adc · touch · spi | ADC2_CH6, TOUCH6, RTC_GPIO16, MTMS, HSPICLK, HS2_CLK, SD_CLK, EMAC_TXD2 |
| 11 | 12 | IO12GPIO12 | strapping | adc · touch · spi | ADC2_CH5, TOUCH5, RTC_GPIO15, MTDI, HSPIQ, HS2_DATA2, SD_DATA2, EMAC_TXD3 |
| 12 | - | GNDN/A | ground | - | Ground connection |
| 13 | 13 | IO13GPIO13 | strapping | adc · touch · spi | ADC2_CH4, TOUCH4, RTC_GPIO14, MTCK, HSPID, HS2_DATA3, SD_DATA3, EMAC_RX_ER |
| 14 | 9 | SHD/SD2GPIO9 | strapping | spi | SD_DATA2, SPIHD, HS1_DATA2, U1RXD |
| 15 | 10 | SWP/SD3GPIO10 | strapping | spi | SD_DATA3, SPIWP, HS1_DATA3, U1TXD |
| 16 | 11 | SCS/CMDGPIO11 | strapping | spi | SD_CMD, SPICS0, HS1_CMD, U1RTS |
| 17 | 6 | SCK/CLKGPIO6 | strapping | spi | SD_CLK, SPICLK, HS1_CLK, U1CTS |
| 18 | 7 | SDO/SD0GPIO7 | strapping | spi | SD_DATA0, SPIQ, HS1_DATA0, U2RTS |
| 19 | 8 | SDI/SD1GPIO8 | strapping | spi | SD_DATA1, SPID, HS1_DATA1, U2CTS |
| 20 | 15 | IO15GPIO15 | strapping | adc · touch · spi | ADC2_CH3, TOUCH3, MTDO, HSPICS0, RTC_GPIO13, HS2_CMD, SD_CMD, EMAC_RXD3 |
| 21 | 2 | IO2GPIO2 | strapping | adc · touch · spi | ADC2_CH2, TOUCH2, RTC_GPIO12, HSPIWP, HS2_DATA0, SD_DATA0 |
| 22 | 0 | IO0GPIO0 | strapping | adc · touch | ADC2_CH1, TOUCH1, RTC_GPIO11, CLK_OUT1, EMAC_TX_CLK |
| 23 | 4 | IO4GPIO4 | strapping | adc · touch · spi | ADC2_CH0, TOUCH0, RTC_GPIO10, HSPIHD, HS2_DATA1, SD_DATA1, EMAC_TX_ER |
| 24 | 16 | IO16GPIO16 | strapping | - | HS1_DATA4, U2RXD, EMAC_CLK_OUT |
| 25 | 17 | IO17GPIO17 | strapping | - | HS1_DATA5, U2TXD, EMAC_CLK_OUT_180 |
| 26 | 5 | IO5GPIO5 | strapping | spi | VSPICS0, HS1_DATA6, EMAC_RX_CLK |
| 27 | 18 | IO18GPIO18 | safe | spi | VSPICLK, HS1_DATA7 |
| 28 | 19 | IO19GPIO19 | safe | spi | VSPIQ, U0CTS, EMAC_TXD0 |
| 29 | - | NCN/A | safe | - | No connection |
| 30 | 21 | IO21GPIO21 | safe | spi | VSPIHD, EMAC_TX_EN |
| 31 | 3 | RXD0GPIO3 | uart | - | U0RXD, CLK_OUT2 |
| 32 | 1 | TXD0GPIO1 | uart | - | U0TXD, CLK_OUT3, EMAC_RXD2 |
| 33 | 22 | IO22GPIO22 | safe | spi | VSPIWP, U0RTS, EMAC_TXD1 |
| 34 | 23 | IO23GPIO23 | safe | spi | VSPID, HS1_STROBE |
| 35 | - | GNDN/A | ground | - | Ground connection |
Start with these
10 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
16 pins · 14 things to knowSENSOR_VPGPIO36 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).
SENSOR_VNGPIO39IO35 Input-only GPIOs with ADC1 channels - no output driver Other
Cannot be used as output; only suitable for input.
- SENSOR_VNInput-only GPIO (no output); ADC1 channel 3, Hall sensor VN.
- IO35Input-only GPIO (no output driver); ADC1 channel 7.
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.
IO14 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.
IO12 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.
IO13 JTAG clock pin (TCK); also ADC2 channel 4 / Touch4 input. JTAG
Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.
IO15 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.
IO2 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.
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.
IO4 Bootstrapping pin; internal pull-down; also HSPIHD (flash data line) on modules with internal flash. Strapping
Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).
IO16IO17 PSRAM chip select and clock on WROVER-class modules; in-package flash lines on ESP32-U4WDH. Both also carry UART2 PSRAM
Wired to the memory die on PSRAM-equipped modules (WROVER, PICO-V3-02) and on in-package-memory chip variants (U4WDH, D0WDRH2-V3); an ordinary GPIO on a plain WROOM-32.
- IO16PSRAM CS# on WROVER-class modules and on ESP32-D0WDRH2-V3; in-package flash CS# on ESP32-U4WDH. Also UART2 RX.
- IO17PSRAM clock on WROVER-class modules; in-package flash IO1/DO on ESP32-U4WDH. Also UART2 TX.
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.
RXD0GPIO3 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.
TXD0GPIO1 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.
Only if you know the tricks
6 pins · 4 things to knowSHD/SD2GPIO9SWP/SD3GPIO10 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.
- SHD/SD2Connected to SPI flash/PSRAM data 2 (SD2, flash HOLD).
- SWP/SD3Connected to SPI flash/PSRAM data 3 (SD3, flash WP).
SCS/CMDGPIO11 Connected to SPI flash command/CS (CMD/CS0). Flash
Used by internal flash (chip select/command); not available for general use.
SCK/CLKGPIO6 Connected to SPI flash clock (SCK/CLK). Flash
Used for internal flash/PSRAM communication; not available for general GPIO.
SDO/SD0GPIO7SDI/SD1GPIO8 SPI flash data lines SD0 and SD1 Flash
Used for internal flash/PSRAM data; not available for general GPIO.
- SDO/SD0Connected to SPI flash data 0 (SD0).
- SDI/SD1Connected to SPI flash data 1 (SD1).
The ESP32-WROOM breaks out 35 pins in total: 32 GPIO for your project, with GND 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, IO32, IO33, IO25, IO26 and 6 more are free of any such role - the safest first picks. 16 of the exposed pins carry boot-time or system duties on the ESP32 (SENSOR_VP, SENSOR_VN, IO34 and 13 more).
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 GPIO32 - wire an LED and resistor to it
void setup() {
pinMode(32, OUTPUT);
}
void loop() {
digitalWrite(32, HIGH); delay(500);
digitalWrite(32, LOW); delay(500);
}[env:esp32-wroom]
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 - GPIO32
output:
- platform: gpio
pin: 32
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).Specifications
ESP32 · 25.5 × 18 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.
32 GPIO are broken out - more than most ESP32 boards, so the pin budget is rarely the constraint.
Resources
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