COP884CG Datasheet, PDF (16/42 Pages) National Semiconductor (TI) – 8-Bit Microcontroller with UART and Three Multi-Function Timers

UART
The COP888CG contains a full-duplex software program-
mable UART The UART (Figure 11) consists of a transmit
shift register a receiver shift register and seven address-
able registers as follows a transmit buffer register (TBUF)
a receiver buffer register (RBUF) a UART control and
status register (ENU) a UART receive control and status
register (ENUR) a UART interrupt and clock source register
(ENUI) a prescaler select register (PSR) and baud (BAUD)
register The ENU register contains flags for transmit and
receive functions this register also determines the length of
the data frame (7 8 or 9 bits) the value of the ninth bit in
transmission and parity selection bits The ENUR register
flags framming data overrun and parity errors while the
UART is receiving
Other functions of the ENUR register include saving the
ninth bit received in the data frame enabling or disabling the
UART’s attention mode of operation and providing addition-
al receiver transmitter status information via RCVG and
XMTG bits The determination of an internal or external
clock source is done by the ENUI register as well as select-
ing the number of stop bits and enabling or disabling trans-
mit and receive interrupts A control flag in this register can
also select the UART mode of operation asynchronous or
synchronous
FIGURE 11 UART Block Diagram
TL DD 9765 – 18
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