UART/IrDA Modes of Operation
12-83
UART Devices
12.8 UART/IrDA Modes of Operation
The UART/IrDA module can operate in two different modes: UART mode and
slow infrared (SIR) mode.
The modules perform serial-to-parallel conversion on data characters
received and parallel-to-serial conversion on data characters transmitted by
the processor. The complete status of each channel of the modules and each
received character/frame can be read at any time during functional operation
via the line control register (LSR).
You can place the modules in an alternate mode (FIFO mode) to relieve the
processor of excessive software overhead by buffering received/transmitted
characters. Both the receiver and transmitter FIFOs can store up to 64 bytes
of data (plus three additional bits of error status per byte for the receiver FIFO)
and have selectable trigger levels.
Both interrupts and DMA are available to control the data-flow between the
host (MPU or DSP) and the module.
12.8.1 UART Mode
The UART uses a wired interface for serial communication with a remote
device.
UART modules are functionally compatible to the TL16C750 UART and are
also functionally compatible with earlier designs such as the TL16C550.
UART modules can use hardware or software flow controls to manage
transmission/reception. Hardware flow control significantly reduces software
overhead and increases system efficiency by automatically controlling serial
data flow using the RTS output and CTS input signals. Software flow control
automatically controls data flow by using programmable XON/XOFF charac-
ters.
12.8.2 SIR Mode
In slow infrared (SIR) mode, data transfer takes place between the host (MPU
or DSP) and peripheral devices at speeds of up to 115200 bauds. An SIR
transmit frame starts with start flags (either a single C0h, multiple C0hs, or a
single C0h preceded by a number of FFh flags), followed by frame data,
CRC - 16, and a stop flag (C1h).
BLR[6] selects whether C0h or FFh start patterns are to be used when multiple
start flags are required.
The SIR transmit state machine attaches start flags, CRC - 16, and stop flags.
It checks the outgoing data to establish if data transparency is required.