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CHAPTER 10 UART
10.1 Overview of UART
The UART is a serial I/O port used to implement asynchronous (start-stop)
communication or CLK synchronous communication.
The MB91F109 contains three UART channels.
UART Characteristics
•
Full duplex double buffer
•
Support of both asynchronous (start-stop) and CLK synchronous communication
•
Support of multiprocessor mode
•
Fully programmable baud rate
•
•
Support for setting any baud rate using external clocks
•
Error detection function (parity errors, framing errors, and overrun)
•
NRZ code for transfer signal
•
Support for starting DMA transfer by an interrupt
UART Registers
Figure 10.1-1 shows the UART registers.
15
7
6
D7
D6
7
6
PE
ORE
7
6
MD1
MD0
7
6
PEN
P
246
Any baud rate can be set using the built-in timer (See Section 9.3, "U-TIMER Operation").
Figure 10.1-1 UART Registers
8
SCR
SSR
8 bit
5
4
3
D5
D4
D3
5
4
3
FRE
RDRF TDRE
5
4
3
CS0
5
4
3
SBL
CL
A/D
7
SMR
SIDR(R)/SODR(W)
8 bit
2
1
0
D2
D1
D0
2
1
0
RIE
TIE
2
1
0
SCKE
SOE
2
1
0
REC
RXE
TXE
0
(R/W)
(R/W)
Serial input data register/serial output
data register (SIDR/SODR)
(SIDR / SODR)
Serial status register
(SSR)
Serial mode register
(SMR)
Serial control register
(SCR)
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