The ESP-03 is a very affordable Wi-Fi module containing the ESP8266EX chip by Espressif. The latter has become very popular among makers who want to affordably add wirelessly controlled smarts to things at home and work.
The ESP-03 has two useful modes of operation that can be initiated by controlling its GPIO pins. The normal mode connections are show in the following figure. The ESP-03 shown here is powered using SparkFun’s FTDI Basic Breakout – 3.3V – USB to serial module.
In normal mode, the ESP-03 runs firmware programmed in the SPI Flash. SPI Flash is an external NOR Flash chip where program instructions can be stored, and retrieved later for execution. The ESP-03 has a 4 Mbit 25Q40BT part which allows for 512 KB of program space. Of that, about 423 KB is available for your own programs.
The second mode is the flash mode, in which new program instructions can be flashed to the SPI Flash, using tools such as the ESP Flash Download Tool. The connections are similar to those for normal mode, with the addition of GPIO0 connected to GND.
The ESP8266 can be programmed using an SDK distributed by Espressif. Popular embedded development platforms such as the Arduino IDE and MicroPython, can also be used to develop firmware for the ESP-03.
Adafruit provides instructions for configuring the Arduino IDE for ESP8266 development. Here’re the settings I use with the ESP-03.
Try out the WiFiWebServer example project under File -> Examples -> ESP8266WiFi. With it, you’ll be controlling a GPIO pin on the ESP-03, over your Wi-Fi network, in no time at all.
Filed under: Arduino, Hardware Design, IoT, USB
