Microcontrollers with USB

What is USB?

USB (Universal Serial Bus) is a widely-used communication protocol for connecting peripherals such as keyboards, mice, storage devices, and other hardware to computers or microcontrollers. It provides high-speed data transfer, plug-and-play functionality, and supports power delivery for connected devices.

Key Features of USB

• High Data Transfer Rates: Supports speeds ranging from 1.5 Mbps (USB 1.0) to 10 Gbps (USB 3.1 and above).
• Standardized Connectors: Includes USB-A, USB-B, Micro-USB, and USB-C connectors for various use cases.
• Power Delivery: Supplies power to connected devices, with USB-C supporting up to 100W.
• Hot-Swappable: Allows devices to be connected or removed without rebooting the system.
• Multiple Device Types: Supports communication with HID (Human Interface Devices), storage devices, audio interfaces, and more.

Microcontrollers with USB Support

Many modern microcontrollers come with built-in USB capabilities, including host, device, or OTG (On-The-Go) support. Examples include:

• Arduino Uno/Leonardo: USB for programming and communication, with Leonardo supporting HID devices.
• ESP32-S2: Provides native USB functionality, ideal for HID and CDC (Communication Device Class) applications.
• STM32 Series: Offers USB Full-Speed and High-Speed controllers for a range of applications.
• Teensy: Advanced USB functionality, including HID, MIDI, and Serial communication.
• Raspberry Pi Pico: Built-in USB controller for serial communication and device emulation.

How to Set Up USB Communication

Setting up USB on a microcontroller involves initializing the USB hardware and configuring it as a host or device. The basic steps are as follows:

Basic Steps:

1. Ensure the microcontroller supports USB and connect the required pins (D+, D-, and VBUS).
2. Select a USB stack or library (e.g., Arduino USB library, TinyUSB).
3. Configure the USB device type (e.g., Serial, HID, Mass Storage).
4. Initialize USB communication in the firmware.
5. Test the connection with a computer or other USB host.

Example Code: USB Communication

Using Arduino as a USB Serial Device

// Example USB Serial Communication on Arduino
void setup() {
    Serial.begin(9600); // Initialize USB Serial communication
    while (!Serial) {
        ; // Wait for Serial connection
    }
    Serial.println("USB Serial Initialized");
}

void loop() {
    if (Serial.available()) {
        char c = Serial.read(); // Read data from USB
        Serial.print("Received: ");
        Serial.println(c);
    }
}
            

Using USB HID on Arduino Leonardo

// Example USB HID Keyboard on Arduino Leonardo
#include 

void setup() {
    Keyboard.begin(); // Initialize USB Keyboard
}

void loop() {
    Keyboard.print("Hello USB!"); // Send text as a keyboard
    delay(1000);
}
            

Troubleshooting USB

Common issues and their solutions:

• Device Not Recognized: Check USB connections, ensure the correct drivers are installed, and verify microcontroller settings.
• Communication Errors: Ensure the USB baud rate and data format match between devices.
• Power Issues: Confirm the USB port provides sufficient power for the connected device.

Example Projects with USB

Project 1: USB Keyboard Emulator

Create a USB device that mimics a keyboard, useful for automation or custom input devices.

Project 2: USB Data Logger

Build a data logger that stores sensor data on a USB drive for easy access and analysis.

Further Reading

To learn more about USB, check out these resources:

• Mastering USB Protocols - A comprehensive guide for beginners and professionals.
• USB Projects for Makers - Practical projects to enhance your USB knowledge.

Conclusion

USB is a versatile and powerful communication protocol that simplifies the connection between devices. Its widespread adoption and advanced capabilities make it a vital component in modern microcontroller applications.