Programmable Auto-RTS\ and Auto-CTS\

In Auto-CTS\ Mode, CTS\ Controls Transmitter

In Auto-RTS\ Mode, RCV FIFO Contents and Threshold Control RTS\

Serial and Modem Control Outputs Drive a RJ11 Cable Directly When Equipment Is on the Same Power Drop

Capable of Running With All Existing TL16C450 Software

After Reset, All Registers Are Identical to the TL16C450 Register Set

Up to 16-MHz Clock Rate for up to 1-Mbaud Operation

In the TL16C450 Mode, Hold and Shift Registers Eliminate the Need for Precise Synchronization Between the CPU and Serial Data

Programmable Baud Rate Generator Allows Division of Any Input Reference Clock by 1 to (216 –1) and Generates an Internal 16× Clock

Standard Asynchronous Communication Bits (Start, Stop, and Parity) Added to or Deleted From the Serial Data Stream

5-V and 3.3-V Operation

Independent Receiver Clock Input

Transmit, Receive, Line Status, and Data Set Interrupts Independently Controlled

Fully Programmable Serial Interface Characteristics:

5-, 6-, 7-, or 8-Bit Characters

Even-, Odd-, or No-Parity Bit Generation and Detection

1-, 1 1/2-, or 2-Stop Bit Generation

Baud Generation (dc to 1 Mbit/s)

False-Start Bit Detection

Complete Status Reporting Capabilities

3-State Output TTL Drive Capabilities for Bidirectional Data Bus and Control Bus

Line Break Generation and Detection

Internal Diagnostic Capabilities:

Loopback Controls for Communications Link Fault Isolation

Break, Parity, Overrun, and Framing Error Simulation

Fully Prioritized Interrupt System Controls

Modem Control Functions (CTS\, RTS\, DSR\, DTR\, RI\, and DCD\)

 

Description for the TL16C550C

The TL16C550C and the TL16C550CI are functional upgrades of the TL16C550B asynchronous communications element (ACE), which in turn is a functional upgrade of the TL16C450. Functionally equivalent to the TL16C450 on power up (character or TL16C450 mode), the TL16C550C and the TL16C550CI, like the TL16C550B, can be placed in an alternate FIFO mode. This relieves the CPU of excessive software overhead by buffering received and transmitted characters. The receiver and transmitter FIFOs store up to 16 bytes including three additional bits of error status per byte for the receiver FIFO. In the FIFO mode, there is a selectable autoflow control feature that can significantly reduce software overload and increase system efficiency by automatically controlling serial data flow using RTS\ output and CTS\ input signals.

 

The TL16C550C and TL16C550CI perform serial-to-parallel conversions on data received from a peripheral device or modem and parallel-to-serial conversion on data received from its CPU. The CPU can read the ACE status at any time. The ACE includes complete modem control capability and a processor interrupt system that can be tailored to minimize software management of the communications link.

 

Both the TL16C550C and the TL16C550CI ACE include a programmable baud rate generator capable of dividing a reference clock by divisors from 1 to 65535 and producing a 16× reference clock for the internal transmitter logic. Provisions are included to use this 16× clock for the receiver logic. The ACE accommodates a 1-Mbaud serial rate (16-MHz input clock) so that a bit time is 1 µs and a typical character time is 10 µs (start bit, 8 data bits, stop bit).

 

Two of the TL16C450 terminal functions on the TL16C550C and the TL16C550CI have been changed to TXRDY\ and RXRDY\, which provide signaling to a DMA controller.