The world of embedded systems is full of challenges, especially when it comes to communication between devices. While USB (Universal Serial Bus) and UART (Universal Asynchronous Receiver/Transmitter) are both serial communication protocols, many wonder whether one can substitute for the other. For example, is it possible to use USB as UART? This question arises particularly when engineers need to interface devices using different communication protocols.
In this article, we will explore the technical aspects of USB and UART communication, analyze the possibility of using USB as UART, and highlight solutions that make this transition seamless. By the end of this post, you’ll have a deeper understanding of how USB to MPSSE/UART adapters bridge the gap between these protocols, and why they are essential in embedded systems and device communication.
Let’s dive in!
Before discussing how USB can serve as UART, let’s first understand what makes each of these protocols unique. Although both are used for data transmission, their design and application differ significantly.
UART is a low-cost, simple communication protocol that has been in use for many years, particularly in microcontrollers and embedded systems. Asynchronous means that there’s no need for a clock signal to synchronize the data transmission. This makes it an ideal solution for many devices where simplicity and flexibility are required.
Asynchronous communication: No clock signal is required for data synchronization.
Low-speed data transfer: UART is typically used for lower-speed communication.
Two-wire communication: Uses only two lines, Tx (transmit) and Rx (receive), making it cost-effective.
Wide applications: Common in microcontrollers, sensors, GPS modules, and other embedded devices.
While UART is effective for many use cases, its limitations in speed and features often push developers to look for alternatives when high-speed data transfer is required.
USB, in contrast, was designed as a versatile, high-speed communication protocol for connecting various peripherals to computers and other devices. It allows for more complex communication and supports higher data transfer speeds, making it a superior choice for modern devices.
Synchronous communication: Uses differential signals for high-speed, reliable communication.
High-speed data transfer: USB supports much faster speeds than UART, from 12 Mbps (USB 1.1) to 40 Gbps (USB4).
Multiple device support: USB allows for the connection of multiple devices via hubs and supports dynamic hot-plugging.
Device enumeration: When a device is connected, the host (typically a computer) detects it and assigns it a unique address.
USB is the preferred interface in most modern computing devices, but its complexity makes it less suited for simple embedded systems, where UART is often the go-to solution.
So, can USB replace UART? The answer is yes, but with a few caveats. The two protocols differ significantly in their electrical characteristics and signaling methods, so they cannot be connected directly without some form of conversion. This is where USB to UART converters come in.
To enable communication between USB and UART devices, a USB to UART adapter is necessary. These adapters serve as the bridge between the two protocols by converting the USB differential signal into the single-ended signal used by UART devices. By using these adapters, developers can leverage USB ports for communication with devices that require UART.
USB to MPSSE/UART converters are a type of adapter that combines the functionality of USB-to-UART conversion with Multi-Protocol Synchronous Serial Engine (MPSSE) support. The MPSSE feature allows these converters to handle multiple communication protocols, including UART, SPI, I2C, and more, over a single USB interface. This provides flexibility for developers working with different types of embedded devices.
Multi-protocol support: A single device can communicate with various peripherals using UART, SPI, and I2C.
Faster communication: MPSSE allows for higher-speed communication compared to standard UART.
Reduced hardware complexity: By using USB for all serial communication, developers eliminate the need for additional ports or interfaces.
Cost-effective: USB to UART converters are inexpensive and widely available, making them accessible for both hobbyists and professionals.
Let’s break down how the conversion between USB and UART happens in a typical USB to MPSSE/UART converter.
Data Transfer via USB: When data is sent from a computer’s USB port, it is transmitted using differential signals (D+ and D-) over the USB connection.
Signal Conversion: The USB to UART adapter contains an integrated chip (like FTDI or CH340) that converts the differential USB signals into the single-ended signals used by UART.
Transmission to UART Devices: The converted signals are then transmitted to the UART device over the Tx and Rx lines, enabling communication.
Reverse Process: When data is received from the UART device, the converter performs the reverse operation, converting the UART signals back into USB differential signals for transmission to the host device.
MPSSE stands for Multi-Protocol Synchronous Serial Engine, and it plays a crucial role in enhancing the versatility of USB to UART converters. MPSSE allows the USB interface to support not only UART but also other synchronous communication protocols such as SPI and I2C.
Higher Data Transfer Rates: MPSSE supports faster data transfer speeds compared to traditional UART.
Synchronous Communication: Unlike standard UART, MPSSE uses a clock signal, enabling faster and more reliable communication.
Multiple Protocol Support: By using MPSSE, a single USB to UART converter can communicate with various devices using different protocols.
This combination of USB, MPSSE, and UART support provides a highly flexible solution for embedded system development and communication with peripherals.
USB to UART converters are essential in various industries, from embedded systems development to industrial automation. Below are some of the most common use cases where USB to UART adapters are indispensable.
Microcontrollers like Arduino, ESP32, and STM32 often use UART for programming and debugging. USB to UART converters allow users to connect their microcontrollers to modern PCs, which typically lack native UART ports. This enables easy programming, debugging, and communication with peripheral devices.
Embedded systems often use UART to communicate with sensors, GPS modules, Bluetooth modules, and other peripherals. A USB to UART adapter allows for seamless communication between these devices and a PC, making it easier for developers to access data and control hardware.
In industrial applications, machines and sensors frequently use UART for communication. USB to UART converters enable these systems to interface with modern computing devices, allowing for real-time monitoring, control, and automation in industrial environments.
Many devices that require data logging, such as environmental monitoring systems or medical devices, use UART to transmit data. USB to UART converters allow data from these devices to be collected on a PC or laptop for further analysis and storage.
Older systems that use UART for communication may not be compatible with modern USB-only computers. USB to UART converters bridge the gap, allowing older systems to communicate with newer devices and software.
As technology evolves, USB continues to advance with new standards like USB 3.0, USB4, and beyond. These new standards will offer even faster data transfer speeds and enhanced functionality, enabling more sophisticated applications for USB to UART converters.
Higher-Speed USB: With the development of USB 3.0 and USB4, data transfer speeds will continue to increase, making USB to UART converters even more efficient.
Integration of Multiple Protocols: MPSSE and similar technologies will allow USB interfaces to support a wider range of serial communication protocols, making converters even more versatile.
Increased Adoption in Embedded Systems: As embedded systems become more complex, the need for flexible, high-speed communication solutions like USB to UART converters will continue to grow.
USB and UART serve as critical communication protocols in the embedded systems world, each with its strengths and limitations. While USB cannot directly replace UART due to differences in signaling, USB to UART converters make it possible to bridge the gap between the two protocols. These converters, particularly those with MPSSE support, offer significant advantages in terms of speed, flexibility, and cost-effectiveness.
Shenzhen Caratar Technology Co., Ltd provides high-quality USB to MPSSE/UART converters, offering advanced features and reliability for a wide range of applications. Whether you're working with microcontrollers, sensors, or industrial systems, Caratar's products can help streamline your communication setup and enhance your project's efficiency.
A: No, USB and UART use different signaling methods, so a USB to UART converter is required for communication between the two.
A: MPSSE (Multi-Protocol Synchronous Serial Engine) is a feature that enables a USB interface to support multiple communication protocols like UART, SPI, and I2C.
A: USB to UART converters use a chip that converts USB differential signals into UART’s single-ended signals, enabling communication between USB-enabled devices and UART devices.
A: MPSSE allows for faster data transfer speeds, synchronous communication, and multi-protocol support, making the converter more versatile and efficient.
A: Shenzhen Caratar Technology Co., Ltd offers high-quality USB to MPSSE/UART converters with advanced features, ideal for embedded systems and device communication.
