MC68HC11P2 Datasheet, PDF (88/268 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Serial Communications Interface (SCI)
The SCI shares I/O with two of port D’s pins:
ST4XCK
Pin
Alternate
function
PD0 RXD1
PD1 TXD1
The SCI transmit and receive functions are enabled by TE and RE
respectively, in SCCR2.
The SCI features enabled on this MCU include: 13-bit modulus
prescaler; idle line detect; receiver-active flag; transmitter and receiver
hardware parity. A block diagram of the enhanced baud rate generator
is shown in Figure 5-1. See Table 5-1 for example baud rate control
values.
13-bit counter
Reset
13-bit compare ^EQ
SCBDH/L: SCI baud control
Internal
phase 2 clock
÷2
Sync
Transmitter
baud rate
clock
÷ 16
Receiver
baud rate
clock
Figure 5-1. SCI baud rate generator circuit diagram
5.3 Data format
The serial data format requires the following conditions:
• An idle-line condition before transmission or reception of a
message.
• A start bit, logic zero, transmitted or received, that indicates the
start of each character.
• Data that is transmitted and received least significant bit (LSB)
first.
Technical Data
Serial Communications Interface (SCI)
For More Information On This Product,
Go to: www.freescale.com
MC68HC11P2 — Rev 1.0