ESP8266-IOT development board

## The reason for making the development board. The source of the development of this ESP8266-IOT is that I bought a book "Teaching you to learn circuit design step by step - based on Lichuang EDA". All the steps are followed step by step in the book. It comes out and is very suitable for novice friends. In addition, a friend asked in the group whether there is any circuit engineering in this book, so I am posting it now. Share it with everyone. ## Circuit introduction: Engineering circuit classification is divided into 4 parts: 1. Main control part. 2. Power supply part. 3. Download part. 4. Sensor part. ## Circuit description Main control circuit ESP! [Main control circuit .png] The power supply part uses the most common and commonly used LDO chip 1117. The circuit solves few peripheral parts. ![Power supply.png]
The download circuit uses the most commonly used CH340C, which has too many features. The biggest feature is that it is cheap and easy to use. ![USB to serial port.png] The reset circuit uses a resistor-capacitor step-down circuit, plus a button reset circuit. The resistance-capacitance reset circuit can realize automatic reset when power is turned on, and the button allows the user to realize independent reset. ![Reset circuit.png] shows the IIC communication protocol used in the display part. Connect a 0.96-inch OLED display for human-computer interaction. ![I2C 0.9 OLED.png] has reserved an interface for the temperature sensor dht11, which can be connected to the dht11 temperature sensor to collect temperature in real time. Displayed on the OLED screen. Use as a thermometer. ![DHT11.png] has reserved a user indicator light. When the display is not connected, the user can observe the current running status of the program through the indicator light. ![User indicator light.png] Sw3 is used as the control part of the startup circuit to choose whether to start normally or download the program to esp8266. ![SW3.png] ![BOOT.png] ## Other instructions### R330 of the serial port circuit The role of resistance. 1. Use for protection to prevent current backflow. 2. Play the role of impedance matching.