Many embedded devices, particularly those found in industrial machines, networking equipment and scientific instruments, have been connected to the host system (such as PC) via the RS-232 interface for configuring hardware, performing firmware updates and diagnostics, and exchanging control signals and data. However, RS-232 has limitations including lower transmission speed, short maximum cable length and large standard connectors. In modern PCs, USB has replaced RS-232 for most of the peripheral interface roles.
Because most host systems (PCs) will have few, or even no, serial ports and only USB ports, you need to use an external or internal USB-to-UART bridge to connect the host system to multiple embedded devices.
The interactive block diagram below illustrates how our products can be integrated to create a USB-to-dual-UART bridge application. Click on each product to learn more about it.
This application demonstrates the use of the USB CDC device class to implement a dual USB-to-UART bridge. A 32-bit SAM D21 microcontroller (MCU) on the SAM D21 Xplained Pro Evaluation Board is used as the USB-to-UART bridge to enumerate two virtual COM ports on the host system:
- Any data sent through the virtual COM ports on the host system, will be seen at the UART port’s Tx pin (on the SAM D21 MCU as the USB-to-UART bridge)
- Any data sent through the UART port’s Rx pin on the SAM D21 MCU will be seen at the virtual COM port on the host system
This solution has been tested to support a transfer rate of up to 1 Mbps (UART baud rate of 1,024,000 bps) and a USB-to-UART bridge with up to two channels.
