Basic knowledge of I/O

For starters, mastering the basics of IO is fundamental to developing IoT applications. In this post, we'll cover IO basics.

Digital IO and Analog IO

IO can be divided into two types: digital IO and analog IO. A digital IO can be a binary device such as a switch, button, etc., and has only two states: on or off. Analog IO can be analog devices such as temperature sensors and light sensors, and its output value is a continuous analog signal, which can be voltage, current, etc.

I/O interface

Digital IO and analog IO can be connected using different interfaces, among which common interfaces are GPIO, I2C, SPI, etc. GPIO is a general-purpose input/output interface that can connect digital devices. I2C and SPI are serial interfaces that can interface digital and analog devices.

GPIO of MCU

MCU is a common controller and a commonly used development tool in IoT development. The GPIO of the single-chip microcomputer is the most familiar to us in the development of the Internet of Things. The GPIO port of the microcontroller has multiple working modes, and different modes can meet different application requirements. The following are several working modes of the GPIO port of the single-chip microcomputer:

Input Mode: GPIO is used as an input port, which can read the level status of external signals, and can use internal pull-up and pull-down resistors or external circuits to provide input levels. In input mode, the output state of GPIO is a high-impedance state, which will not affect external circuits.

Output Mode: GPIO is used as an output port, which can control the state of external devices, output high level or low level. In output mode, the output level of GPIO can be controlled by programming, which can be high level, low level or high impedance state. Usually, it is necessary to pay attention to the current and voltage parameters of the external circuit.

Open-drain output mode (Open-drain Output Mode): also known as open-drain output mode or bidirectional open-drain output mode, can control the state of external devices, but can only output low level, when high level will set the output port to to a high-impedance state. Therefore, if you need to output a high level, you usually need an external pull-up resistor to pull the output level high.

Tri-state Output Mode (Tri-state Output Mode): also known as high-impedance output mode, which can put GPIO in high-impedance state without output level, usually used in scenarios where multiple channels share signal lines.

IO application scenarios

IO has a wide range of application scenarios in the Internet of Things, such as:

Control smart home devices: By controlling the IO ports of smart sockets, smart lights and other devices, the switch and brightness of the devices can be controlled.

Monitoring of environmental parameters: By connecting the IO ports of analog devices such as temperature sensors and humidity sensors, environmental parameters can be monitored in real time.

Data collection and transmission: By connecting the IO port of the sensor, the data collection and transmission can be realized, such as GPS positioning, accelerometer and other sensors.

Summarize

The above is the basic knowledge of IO and the introduction of MCU related content. Understanding the basics of IO is very important for developing IoT applications, because IO is the most common way of data interaction in IoT devices. The single-chip microcomputer is a commonly used development tool in the development of the Internet of Things. Mastering the IO programming of the single-chip microcomputer can realize the development of various Internet of Things applications.

Hope this article can help readers to better understand the basics of IO and help in IoT development.

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