Description

The D16750 is a soft Core of a Universal Asynchronous Receiver / Transmitter (UART), functionally identical to the TL16C750. The D16750 allows serial transmission in two modes – UART and FIFO. In the FIFO mode, internal FIFOs are activated allowing up to 512 bytes (plus 3 bits data error per byte in the RCVR FIFO) to be stored both in receive and transmit directions. Our trustworthy core performs serial-to-parallel conversion on data characters received from a peripheral device or from MODEM, and a parallel-to-serial conversion on data characters received from the CPU. The CPU can read a complete status of the UART at any time during functional operation. Reported status information includes a type and condition of transfer operations performed by the UART, as well as any error conditions (parity, overrun, framing or break interrupt). The D16750 includes a programmable baud rate generator, which is capable of dividing the timing reference clock input by divisors of 1 to (216-1) and producing a 16 × clock for driving internal transmitter logic. Provisions are also included to use this 16 × clock to drive receiver logic. What’s more important, our revolutionary core has a complete MODEM control capability and processor-interrupt system. Thanks to it, interrupts can be programmed in accordance to your requirements, minimizing the computing required to handle the communication link. A separate BAUD CLK line allows to set an exact transmission speed, while the UART internal logic is clocked with CPU frequency. The configuration capability allows you to enable or disable the Modem Control Logic and FIFO’s, or change the FIFO’s size during the Synthesis process. So, in applications with area limitation and where the UART works only in the 16450 mode, disabling Modem Control and FIFO’s allow saving about 50% of logic resources. The core is perfect for applications where the UART Core and microcontroller are clocked by the same clock signal and are implemented inside the same ASIC or FPGA chip, as well as for standalone implementation, where several UARTs are required to be implemented inside a single chip and driven by some off-chip devices. Thanks to a universal interface, the D16750 core implementation and verification are very simple, just by eliminating a number of clock trees in the complete system. Moreover, we have implemented a selectable autoflow control feature in the FIFO mode. What does it mean for you? Thanks to this useful feature, you can significantly reduce software overload and increase system efficiency. It’ll be done automatically by controlling serial data flow through the RTS output and the CTS input signals. The D16750 includes fully automated test bench with complete set of tests, allowing easy package validation at each stage of SoC design flow. Our core is a technology independent design, which can be implemented in variety of process technologies.

Key features

  • Software compatible with 16450, 16550 and 16750 UARTs
  • Configuration capability
  • Separate configurable BAUD clock line
  • Majority Voting Logic
  • Supports RS232 and RS485 standards
  • Two modes of operation: UART mode and FIFO mode
    • In the FIFO mode transmitter and receiver are each buffered with 64 byte FIFO to reduce the number of interrupts presented to the CPU
    • In UART mode receiver and transmitter are double buffered to eliminate a need for precise synchronization between the CPU and serial data
  • Configurable FIFO size allowing up to 512 levelsdeep FIFOs in both Rx and Tx directions.
  • 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)
  • Programmable automatic Hardware Flow Control logic through Auto-RTS and Auto-CTS
  • 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 Bus
    • Altera Avalon Bus
    • Xilinx OPB Bus
  • Fully synthesizable

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