MC9S08RG60 Datasheet, PDF (144/232 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface (SCI) Module
11.1 Features
Features of SCI module include:
• Full-duplex, standard non-return-to-zero (NRZ) format
• Double-buffered transmitter and receiver with separate enables
• Programmable baud rates (13-bit modulo divider)
• Interrupt-driven or polled operation:
– Transmit data register empty and transmission complete
– Receive data register full
– Receive overrun, parity error, framing error, and noise error
– Idle receiver detect
• Hardware parity generation and checking
• Programmable 8-bit or 9-bit character length
• Receiver wakeup by idle-line or address-mark
11.2 SCI System Description
The SCI allows full-duplex, asynchronous, NRZ serial communication among the MCU and remote
devices, including other MCUs. The SCI comprises a baud rate generator, transmitter, and receiver block.
The transmitter and receiver operate independently, although they use the same baud rate generator.
During normal operation, the MCU monitors the status of the SCI, writes the data to be transmitted, and
processes received data. The following describes each of the blocks of the SCI.
11.3 Baud Rate Generation
As shown in Figure 11-2, the clock source for the SCI baud rate generator is the bus-rate clock.
MODULO DIVIDE BY
(1 THROUGH 8191)
BUSCLK
SBR12:SBR0
BAUD RATE GENERATOR
OFF IF [SBR12:SBR0] = 0
DIVIDE BY
16
Tx BAUD RATE
Rx SAMPLING CLOCK
(16 × BAUD RATE)
BUSCLK
BAUD RATE =
[SBR12:SBR0] × 16
Figure 11-2 SCI Baud Rate Generation
144
MC9S08RC/RD/RE/RG
Freescale Semiconductor