MC81F4x16
24. UART
Data Bus
TB8
S
BRDATA
D
Q
UDAT
CLK
RxD
TxD
TxD
1/8
1/4
1/2
1/1
UMS0
UMS1
M
U
X
Baud Rate
Generator
CLK
Zero Detector
Write to
UDAT
Shift
Start
UCLK
EN
Tx Control
Tx Clock
Send
UTIR
Uart Tx INT request
UTIF
Uart Tx INT enable
UTIE
UART Tx INT
Shift
Clock
URIE
UART Rx INT
URIF
Uart Rx INT enable
Uart Rx INT request
URIR
Receive
Rx Clock
Start
SDR
URIR
Rx Control
Shift
1-to-0
Transition
Detector
Shift
Value
Bit Detector
Shift
Register
UMS0
UMS1
UDAT
RxD
Data Bus
Figure 24-1 UART Block Diagram
The UART block has four communication modes. One synchronous mode and three UART (Universal
Asynchronous Receiver/Transmitter) modes.
-
Mode 0 : Serial I/O with baud rate of fxx/(16 × (BRDAT+1))
half-duplex and master mode only
-
-
-
Mode 1 : 8-bit UART mode; variable baud rate : no parity bit
Mode 2 : 9-bit UART mode; fxx/16
Mode 3 : 9-bit UART mode, variable baud rate
October 19, 2009 Ver.1.35
151
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