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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.
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UART Characteristics
• Full duplex double buffer
• Support of both asynchronous (start-stop) and CLK synchronous communication
• Support of multiprocessor mode
• Fully programmable baud rate
• Any baud rate can be set using the built-in timer (See Section 9.3, "U-TIMER Operation").
• 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
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UART Registers
Figure 10.1-1 shows the UART registers.
Figure 10.1-1 UART Registers
15 8 7 0
SCR SMR (R/W)
SSR SIDR(R)/SODR(W) (R/W)
8 bit 8 bit
76543210
D7 D6 D5 D4 D3 D2 D1 D0
(SIDR / SODR)
76543210
PE ORE FRE RDRF TDRE RIE TIE
(SSR)
76543210
MD1 MD0 CS0 SCKE SOE
(SMR)
76543210
PEN P SBL CL A/D REC RXE TXE
(SCR)
Serial input data register/serial output
data register (SIDR/SODR)
Serial status register
Serial mode register
Serial control register