MC68HC908KX8 Datasheet, PDF (197/310 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface Module (SCI)
I/O Signals
14.7 I/O Signals
Port B shares two of its pins with the SCI module. The two SCI I/O pins
are:
• TxD — Transmit data
• RxD — Receive data
14.7.1 TxD (Transmit Data)
The TxD pin is the serial data output from the SCI transmitter. The SCI
shares the TxD pin with port B. When the SCI is enabled, the TxD pin is
an output regardless of the state of the DDRB5 bit in data direction
register B (DDRB).
14.7.2 RxD (Receive Data)
The RxD pin is the serial data input to the SCI receiver. The SCI shares
the RxD pin with port B. When the SCI is enabled, the RxD pin is an input
regardless of the state of the DDRB4 bit in data direction register B
(DDRB).
14.8 I/O Registers
These I/O registers control and monitor SCI operation:
• SCI control register 1 (SCC1)
• SCI control register 2 (SCC2)
• SCI control register 3 (SCC3)
• SCI status register 1 (SCS1)
• SCI status register 2 (SCS2)
• SCI data register (SCDR)
• SCI baud rate register (SCBR)
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
MOTOROLA
Serial Communications Interface Module (SCI)
Technical Data
197