MC68HC11E Family
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Rev. 4
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
145
Technical Data
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M68HC11E Family
Section 7. Serial Communications Interface (SCI)
7.1 Contents
7.2
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
7.3
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
7.4
Transmit Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
7.5
Receive Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148
7.6
7.6.1
7.6.2
Wakeup Feature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Idle-Line Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Address-Mark Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . .150
7.7
SCI Error Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151
7.8
7.8.1
7.8.2
7.8.3
7.8.4
7.8.5
SCI Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152
Serial Communications Data Register . . . . . . . . . . . . . . . .152
Serial Communications Control Register 1 . . . . . . . . . . . .153
Serial Communications Control Register 2 . . . . . . . . . . . .154
Serial Communication Status Register. . . . . . . . . . . . . . . .155
Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
7.9
Status Flags and Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . .160
7.10
Receiver Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
7.2 Introduction
The serial communications interface (SCI) is a universal asynchronous
receiver transmitter (UART), one of two independent serial input/output
(I/O) subsystems in the M68HC11 E series of microcontrollers. It has a
standard non-return-to-zero (NRZ) format (one start bit , eight or nine
data bits, and one stop bit). Several baud rates are available. The SCI