ESP8266 Module Development – Based on Arduino IDE

1. Introduction to the Wildfire ESP8266 Module

  The ESP8266 features a high-performance wireless SOC, bringing good news to mobile platform designers. It offers maximum utility at the lowest cost, providing endless possibilities for embedding WiFi functionality into other systems. The ESP8266 is a complete and self-contained WiFi network solution that can operate independently or serve as a slave connected to another host. When the ESP8266 is the only application processor in the device, it can boot directly from external flash memory. The built-in high-speed buffer memory enhances system performance and reduces memory requirements. The ESP8266 is highly integrated on-chip, including antenna switch balun and power management converter, which minimizes the need for external circuitry and reduces the PCB space occupied by the entire solution, including the front-end module, during design. Operating voltage is 3.3V, average operating current is 80mA.Note The actual purchased module only has one light…….Module Schematic or onboard schematicESP8266 Manual Pin Description  The ESP8266EX has a total of 17 GPIO pins, which can be assigned different functions by configuring the appropriate registers. Each GPIO can be configured for internal pull-up/down, or set to high impedance. When configured as input, the input value can be obtained by reading the register; inputs can also be set to edge-triggered or level-triggered to generate CPU interrupts. In short, IO pins are bidirectional, non-inverting, and tri-state, with tri-state control for input and output buffers. These pins can be reused for other functions, such as I2C, I2S, UART, PWM, IR remote control, LED Light, and Button interfaces, etc.  In low power mode, GPIO can be set to hold state. For example, when the chip is powered off, all output enable signals can be set to hold in low power mode. Selective hold functionality can be embedded into IO as needed. When IO is not driven by external circuits, the hold function can be used to maintain the last state. The hold function introduces some positive feedback into the pins. Therefore, the external drive for the pins must be stronger than the positive feedback. The drive required to exit the hold state is very small, within 5 μA.

2. Hardware Connection

Module PinsPin DescriptionConnection method, using Dupont wiresGND < —- > GND VCC < —- > 3.3V CH_PD < —- > 3.3V RST can be left floating, connect to low level when reset GPIO2 and GPIO0 can be left floating, when downloading the program via serial, GPIO2 should be connected to 3.3V, and GPIO0 should be connected to GND.

3. Project Creation

The code is as follows:

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 115200 bits per second:
  Serial.begin(115200);
}

// the loop routine runs over and over again forever:
void loop() {
  Serial.println("hello ");
  delay(1000);  // delay 
  Serial.println("world");
  delay(1000);  // delay 
}

The function is to print hello world via serial.

CompileSelect the development board and serial port numberThe program needs to connect GPIO2 to 3.3V and GPIO0 to GND when downloading through the serial port. Press the reset button, then click download, and release the reset button, and wait for the download to complete.

4. Experiment Testing

GPIO2 and GPIO0 are left floating, reset the program, and you can see it continuously printing hello world

References：

https://www.espressif.com.cn/zh-hans/support/documents/technical-documents?keys=ESP8266+???&field_type_tid[]=14

http://www.taichi-maker.com/homepage/iot-development/iot-dev-reference/esp8266-c-plus-plus-reference/