MC68HC908MR8 Datasheet, PDF (263/372 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface (SCI)
I/O Signals
13.8 I/O Signals
Port B shares two of its pins with the SCI module. The two SCI I/O pins
are:
• PTB1/TxD — Transmit data
• PTB0/RxD — Receive data
13.8.1 PTE2/TxD (Transmit Data)
The PTB1/TxD pin is the serial data output from the SCI transmitter. The
SCI shares the PTB1/TxD pin with port B. When the SCI is enabled, the
PTB1/TxD pin is an output regardless of the state of the DDRF1 bit in
data direction register B (DDRB).
13.8.2 PTB0/RxD (Receive Data)
The PTB0/RxD pin is the serial data input to the SCI receiver. The SCI
shares the PTB0/RxD pin with port B. When the SCI is enabled, the
PTB0/RxD pin is an input regardless of the state of the DDRB0 bit in data
direction register B (DDRB).
13.9 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)
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Serial Communications Interface (SCI)
Technical Data
263