MC80F0424 Datasheet, PDF (86/135 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC80F0424/0432/0448
Preliminary
17. UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART)
17.1 UART Serial Interface Functions
The Universal Asynchronous Receiver/Transmitter(UART) en-
ables full-duplex operation wherein one byte of data after the start
bit is transmitted and received. The on-chip baud rate generator
dedicated to UART enables communications using a wide range
of selectable baud rates. In addition, a baud rate can also be de-
fined by dividing clocks input to the ACLK pin.
The UART driver consists of RXR, TXR, ASIMR, ASISR and
BRGCR register. Clock asynchronous serial I/O mode (UART)
can be selected by ASIMR register. Figure 17-1 shows a block di-
agram of the UART driver.
In operation of UART0 and UART1, their operations are same as
UART0 and UART1
Note: The UART1 control register ASIMR1,ASISR1,
BRGCR1, RXR1 and TXR1 are located at EE6H ~ EE9H
address. These address must be controlled (read and writ-
ten) by absolute addressing manipulation instruction.
Internal Data Bus
Receive Buffer Register
(RXR / RXR1)
RXE
RxD0 PIN /
RxD1 PIN
TXE
TxD0 PIN /
TxD1 PIN
Receive Shift Register
(RXSR)
2
1
0
PE FE OVE (ASISR /
ASISR1)
Transmit Shift Register
(TXR / TXR1)
Transmit Controller
(Parity Addition)
ACLK0 PIN /
ACLK1 PIN
f_XIN/2 ~ f_XIN/128
Receive Controller
(Parity Check)
Baud Rate
Generator
IFRX0 / IFRX1
IFTX0 / IFTX1
UART0IF /
UART1IF
(UART0/1 interrupt)
Figure 17-1 UART Block Diagram
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MAR. 2005 Ver 0.2