OLIMEX ESP32-GATEWAY
ESP32 dev board with 100 Mbit Ethernet and a microSD slot - built for wired IoT gateway projects.
Pinout
13 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | TXPWM | uart | uart | |
| 2 | 3 | RXPWM | uart | uart | |
| 3 | 5 | ETH_PHY_POWERSSPWM | strapping | spi | |
| 4 | 16 | SCLPWM | strapping | i2c | |
| 5 | 18 | SCKPWM | safe | spi | |
| 6 | 19 | MISOPWM | safe | spi | |
| 7 | 23 | MOSIPWM | safe | spi | |
| 8 | 32 | SDAA4T9PWM | safe | adc · touch · i2c | |
| 9 | 33 | LED_BUILTINPWM | safe | - | |
| 10 | 34 | KEY_BUILTIN | strapping | - | |
| 11 | 35 | A7 | strapping | adc | |
| 12 | 36 | A0 | strapping | adc | |
| 13 | 39 | A3 | strapping | adc |
Start with these
5 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
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| ETH_PHY_POWER | GPIO5 | Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot. | Strapping |
| KEY_BUILTIN | GPIO34 | Cannot be used as output (no drive capability); only suitable for analog/digital input. | Other |
| A7 | GPIO35 | Cannot be used as output; only suitable for input. | Other |
| A0 | GPIO36 (SENSOR_VP) | Cannot be used as output; only suitable for input (e.g., analog read). | Other |
| A3 | GPIO39 (SENSOR_VN) | Cannot be used as output; only suitable for input. | Other |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| 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 |
| 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 |
| SCL | GPIO16 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
Pinout notes The OLIMEX ESP32-GATEWAY pinout brings out 13 GPIO pins at a 2.54 mm pitch - every one of them usable in your project. For peripherals, I²C is mapped to SDA on…
The OLIMEX ESP32-GATEWAY pinout brings out 13 GPIO pins at a 2.54 mm pitch - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO32 and SCL on GPIO16; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.
On the analog side there are 4 ADC-capable pins for sensors and battery monitoring and 1 capacitive-touch inputs.
If you want zero surprises, SCK, MISO, MOSI, SDA and 1 more are free of any such role - the safest first picks. 5 of the exposed pins carry boot-time or system duties on the ESP32 (ETH_PHY_POWER, KEY_BUILTIN, A7 and 2 more).
Getting started
flash your first firmware in ~2 minutesBoard: Esp32 Gateway
Flash Size: 4MB · DIO
Upload Speed: 921600
// blink
pinMode(18, OUTPUT);
digitalWrite(18, LOW); // on (often inverted)[env:esp32-gateway]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32dev
variant: esp32-gateway
framework:
type: esp-idf
# blink - GPIO18
output:
- platform: gpio
pin: 18
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binSpecifications
ESP32 · 62 × 50 mmAbout this board
At its core is the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.
Expect to pay about $19.74 - in line with other ESP32 boards.
Only 13 GPIO are broken out, where most ESP32 boards manage about 24 - worth checking the pinout covers what you need.
Onboard you'll find a microSD slot, wired Ethernet (LAN8710A), status LEDs (Power, User) and Reset/User buttons.
- Optional external antenna variant (-EA) uses ESP32-WROOM-32UE with u.FL connector
- Industrial-grade variant (-IND) rated -40 to +85C
Where to buy
prices are typical street pricesResources
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