ESP8685-WROOM-03 Pinout

Overview

The ESP8685-WROOM-03 is built around the ESP8685 chip, an enhanced version of the ESP8684 used in the ESPC2-02 guide, both are marketed by Espressif as “ESP32-C2” family parts. This module packs the chip, flash, and RF components into an 11-pin package with an exposed ground pad underneath.

No 802.15.4 radio on this chip, so Thread and Zigbee aren’t possible here.

Getting started

This module is usually wired up directly rather than plugged into a ready-made development board, so you’ll need a USB-to-serial adapter (3.3V) and a way to pull GPIO9 low for flashing.

Hello World: blink an LED

The microcontroller equivalent of “Hello World”: GPIO1 toggles once a second. Wire an LED (with a resistor) to GPIO1, the only exposed pin here with no PWM/JTAG/ADC role competing for it.

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"

#define LED_PIN GPIO_NUM_1

void app_main(void)
{
    gpio_reset_pin(LED_PIN);
    gpio_set_direction(LED_PIN, GPIO_MODE_OUTPUT);

    while (1) {
        gpio_set_level(LED_PIN, 1);
        vTaskDelay(pdMS_TO_TICKS(1000));
        gpio_set_level(LED_PIN, 0);
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

#define LED_PIN 1

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(1000);
  digitalWrite(LED_PIN, LOW);
  delay(1000);
}

ESP-IDF: build and flash with idf.py build flash monitor. Arduino IDE: install ESP32 board support first, see “Getting started” above.

Specifications

Official specifications for the ESP8685-WROOM-03 module.

Pinout diagram

The 11-pin layout of the ESP8685-WROOM-03 module.

GPIO quick reference

Flashing pins (UART0)

Used by a USB-to-serial adapter to upload firmware, this module has no onboard one.

Safety notes