Chapter 11
Serial Communications Interface Module (SCI)
11.1 Introduction
The MC68HC908AP64 has two SCI modules:
•
•
SCI1 is a standard SCI module, and
SCI2 is an infrared SCI module.
This section describes SCI1, the serial communications interface (SCI) module, which allows high-speed
asynchronous communications with peripheral devices and other MCUs.
NOTE
When the SCI is enabled, the TxD pin is an open-drain output and requires
a pullup resistor to be connected for proper SCI operation.
11.2 Features
Features of the SCI module include the following:
•
•
•
•
•
•
•
•
Full-duplex operation
Standard mark/space non-return-to-zero (NRZ) format
32 programmable baud rates
Programmable 8-bit or 9-bit character length
Separately enabled transmitter and receiver
Separate receiver and transmitter CPU interrupt requests
Programmable transmitter output polarity
Two receiver wakeup methods:
–
–
Idle line wakeup
Address mark wakeup
•
Interrupt-driven operation with eight interrupt flags:
–
–
–
–
–
–
–
–
Transmitter empty
Transmission complete
Receiver full
Idle receiver input
Receiver overrun
Noise error
Framing error
Parity error
•
•
•
•
Receiver framing error detection
Hardware parity checking
1/16 bit-time noise detection
Configuration register bit, SCIBDSRC, to allow selection of baud rate clock source
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
155
FREESCALE [ Freescale ]
