MC68HC05C9A Datasheet, PDF (53/124 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 9
Serial Communications Interface (SCI)
9.1 Introduction
This section describes the on-chip asynchronous serial communications interface (SCI). The SCI allows
full-duplex, asynchronous, RS232 or RS422 serial communication between the microcontroller unit
(MCU) and remote devices, including other MCUs. The transmitter and receiver of the SCI operate
independently, although they use the same baud rate generator.
9.2 Features
Features of the SCI include:
• Standard mark/space non-return-to-zero format
• Full-duplex operation
• 32 programmable baud rates
• Programmable 8-bit or 9-bit character length
• Separately enabled transmitter and receiver
• Two receiver wakeup methods:
– Idle line wakeup
– Address mark wakeup
• Interrupt-driven operation capability with five interrupt flags:
– Transmitter data register empty
– Transmission complete
– Transmission data register full
– Receiver overrun
– Idle receiver input
• Receiver framing error detection
• 1/16 bit-time noise detection
NOTE
The serial communications data register (SCI SCDR) is controlled by the
internal R/W signal. It is the transmit data register when written to and the
receive data register when read.
MC68HC05C9A Advance Information Data Sheet, Rev. 5.1
Freescale Semiconductor
53