NXP SC16IS750: Bridging UART and I2C/SPI for Embedded Systems

In the world of embedded systems, efficient communication between microcontrollers and peripheral devices is crucial. Many microcontrollers feature Universal Asynchronous Receiver/Transmitters (UARTs) for serial communication, but the number of available hardware UARTs is often limited. Conversely, buses like I²C (Inter-Integrated Circuit) and SPI (Serial Peripheral Interface) are commonly available and excel at connecting multiple devices with fewer I/O pins. The NXP SC16IS750 bridge IC elegantly solves the interface mismatch, providing a robust solution for expanding serial connectivity.

This versatile chip functions as a single-channel UART with an I²C or SPI interface, allowing a host microcontroller to communicate with standard serial devices (like sensors, modems, or GPS modules) using a simple two-wire I²C bus or a four-wire SPI bus. It effectively translates protocols on the fly, offloading the demanding task of UART communication from the main microcontroller. This is particularly valuable for microcontrollers that are rich in I²C/SPI but have few or no hardware UARTs.

The core functionality of the SC16IS750 revolves around its high-performance UART core. It supports data rates up to 5 Mbit/s (with a 80 MHz clock) and includes 64-byte FIFOs (First-In, First-Out buffers) for both transmit and receive paths. These FIFOs are critical for reducing the interrupt loading on the host processor, enabling smoother system operation and higher data throughput without loss. The UART features are comprehensive, including programmable data format (data bits, stop bits, parity), hardware flow control signals (RTS/CTS), and modem control signals, making it compatible with a vast array of existing serial devices.

A key advantage of the SC16IS750 is its dual-bus interface option. Designers can select either I²C (with a maximum speed of 400 kbit/s in Fast-mode) or SPI (up to 15 Mbit/s as a slave device) as the control interface, providing flexibility to fit into different system architectures. This choice allows engineers to optimize for speed (favoring SPI) or for minimizing pin count (favoring I²C).

From a software perspective, the IC is designed for easy integration. It features register-based control that is fully compatible with the industry-standard 16C450 UART, which simplifies driver development. Experienced embedded developers can quickly port existing code to manage the device, significantly shortening the development cycle.

Typical applications are widespread. It is used to add extra serial ports to Raspberry Pi or Arduino platforms, interface with legacy industrial equipment that uses RS-232 or RS-485, manage multiple GPS receivers, or connect wireless modules (like Wi-Fi or Bluetooth) over a simple I²C bus, thereby conserving the microcontroller's precious hardware UARTs for other critical tasks.

ICGOOODFIND: The NXP SC16IS750 is an indispensable bridge IC for modern embedded design, offering a seamless and high-performance pathway to convert between UART and I²C/SPI protocols. Its integrated FIFOs, flexible bus options, and software compatibility make it an optimal solution for expanding serial connectivity while optimizing processor load and board space.

Keywords: UART-to-I²C/SPI bridge, Serial Port Expansion, FIFO Buffers, Protocol Converter, Embedded Systems Communication.