TL16C550D_09 Datasheet, PDF (41/54 Pages) Texas Instruments – ASYNCHRONOUS COMMUNICATIONS ELEMENT WITH AUTOFLOW CONTROL

TL16C550D, TL16C550DI
www.ti.com .................................................................................................................................................. SLLS597E – APRIL 2004 – REVISED DECEMBER 2008
Scratch Register
The scratch register is an 8-bit register that is intended for the programmer's use as a scratchpad in the sense
that it temporarily holds the programmer's data without affecting any other ACE operation.
Transmitter Holding Register (THR)
The ACE transmitter section consists of a THR and a transmitter shift register (TSR). The THR is actually a
16-byte FIFO. Timing is supplied by BAUDOUT. Transmitter section control is a function of the ACE line control
register.
The ACE THR receives data off the Internal data bus and when the shift register is idle, moves it into the TSR.
The TSR serializes the data and outputs it at SOUT. In the TL16C450 mode, if the THR is empty and the
transmitter-holding-register-empty (THRE) interrupt is enabled (IER1 = 1), an interrupt is generated. This interrupt
is cleared when a character is loaded into the register. In the FIFO mode, the interrupts are generated based on
the control setup in the FIFO control register.
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