D16450

D16450 UART IP Core – Classic Asynchronous UART for FPGA & ASIC

The D16450 UART IP Core from DCD-SEMI is a compact and reliable Universal Asynchronous Receiver/Transmitter (UART) designed for FPGA and ASIC integration. Delivered as a flexible bridge to APB, AHB, and AXI bus architectures, the D16450 is functionally identical to the TL16C450, ensuring full compatibility with legacy software and hardware environments.

The core performs serial-to-parallel conversion for data received from peripherals or MODEMs and parallel-to-serial conversion for data transmitted from the CPU, providing a proven and deterministic UART implementation for embedded systems.

Complete Status Visibility and Error Reporting

The processor can read the full UART status at any time during operation. Status information includes:

• Current transfer operation state

• Parity, overrun, framing, and break error detection

• Interrupt source identification

This comprehensive reporting ensures predictable communication behavior and simplifies software development and debugging.

Programmable Baud Rate and Flexible Clocking

The D16450 integrates a programmable baud rate generator capable of dividing a reference clock by divisors from 1 to (2¹⁶ − 1), generating a 16× clock for the internal transmitter logic. The same clock can also be used to drive the receiver logic.

A dedicated BAUD CLK input allows designers to set an exact transmission speed, while the UART internal logic continues to operate at the CPU clock frequency. This separation simplifies timing closure and improves design robustness.

MODEM Control and Interrupt-Driven Operation

The core includes full MODEM control capability and a programmable processor interrupt system, allowing efficient, interrupt-driven communication. Interrupts can be tailored to application requirements, minimizing CPU overhead and eliminating unnecessary polling.

Optimized for SoC and Multi-UART Designs

The D16450 is ideal for systems where the UART and microcontroller share the same clock domain inside a single FPGA or ASIC. Its universal interface reduces clock-tree complexity and significantly simplifies both implementation and verification.

The core is also well suited for standalone multi-UART designs, where several UART instances are implemented within one chip and connected to off-chip devices.

Verification-Ready and Technology Independent

Like all DCD-SEMI UART IP Cores, the D16450 is delivered with a fully automated testbench and complete test suite, enabling straightforward validation throughout every stage of the SoC design flow.

The IP Core is technology-independent and can be implemented across a wide range of FPGA and ASIC process technologies.

Typical Applications

• Legacy UART replacement

• Embedded controllers and SoCs

• Industrial and instrumentation systems

• FPGA-based multi-UART designs

• ASIC designs requiring deterministic serial communication

Which UART IP Core Should You Choose?

Choosing the right UART IP Core depends on software compatibility, throughput requirements, and CPU load constraints. DCD-SEMI offers three UART solutions covering classic legacy replacement up to high-performance designs.

Quick Decision Guide

Choose D16450 if:

• You are replacing a TL16C450 / 16450 UART

• You need 100% register compatibility

• Minimal validation effort is critical

Choose D16550 if:

• You need FIFO buffering but still want classic UART behavior

• You are migrating from 16550-based systems

• Moderate throughput improvement is required

Choose D16950 if:

• You need maximum throughput and lowest CPU load

• Large FIFO depth and advanced flow control are required

• You are upgrading legacy UARTs in performance-critical systems

Feature Comparison Table

Engineering Trade-Offs Explained

D16450 – Lowest Risk Legacy Replacement

• Exact behavior match to legacy hardware

• No FIFO → deterministic timing

• Best choice when software must remain untouched

Best for: industrial legacy systems, PC-compatible UART emulation

D16550 – Balanced Upgrade Path

• Adds FIFO buffering to reduce interrupts

• Still widely supported by legacy drivers

• Good compromise between compatibility and performance

Best for: embedded Linux, RTOS-based systems

D16950 – Performance-Oriented Modern UART

• Deep FIFOs dramatically reduce CPU overhead

• Autoflow control prevents data loss at high speeds

• Supports multi-UART SoCs and clock-synchronous designs

Best for: telecom, industrial gateways, FPGA-based SoCs

Migration Scenarios

Migrating from Discrete UART ICs to FPGA/ASIC

• 16450 IC → D16450 (no software changes)

• 16550 IC → D16550 (minimal validation)

• OX16C950 → D16950 (performance parity or better)

Selection Summary

ALL DCD’S IP CORES ARE TECHNOLOGY AGNOSTIC, ENSURING 100% COMPATIBILITY WITH ALL FPGA AND ASIC VENDORS.

For further details, email info@dcd-semi.com.

• Software compatible with 16450 UART
• Configuration capability
• Separate configurable BAUD clock line
• Majority Voting Logic
• Adds or deletes standard asynchronous communication bits (start, stop and parity) to or from the serial data
• Independently controlled transmit, receive, line status and data set interrupts
• False start bit detection
• 16 bit programmable baud generator
• Independent receiver clock input
• MODEM control functions (CTS, RTS, DSR, DTR, RI and DCD)
• Fully programmable serial-interface characteristics:
  • 5-, 6-, 7-, or 8-bit characters
  • Even, odd, or no-parity bit generation and detection
  • 1-, 1,5-, or 2-stop bit generation
  • Internal baud generator
• Complete status reporting capabilities
• Line break generation and detection. Internal diagnostic capabilities:
  • Loop-back controls for communications link fault isolation
  • Break, parity, overrun, framing error simulation
• Full prioritized interrupt system controls
• Available system interface wrappers:
  • AMBA – APB / AHB / AXI Bus
  • Altera Avalon Bus
  • Xilinx OPB Bus
• Fully synthesizable
• Static synchronous design and no internal tri-states