MC908AP32CFBE Datasheet, PDF (168/324 Pages) Freescale Semiconductor, Inc – The following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location.

Serial Communications Interface Module (SCI)
NOTE
The PTB2/TxD pin is an open-drain pin when configured as an output.
Therefore, when configured as a general purpose output pin (PTB2), a
pullup resistor must be connected to this pin.
11.7.2 RxD (Receive Data)
When the SCI is enabled (ENSCI=1), the PTB3/RxD pin becomes the serial data input, RxD, to the SCI
receiver regardless of the state of the DDRB3 bit in data direction register B (DDRB).
NOTE
The PTB3/RxD pin is an open-drain pin when configured as an output.
Therefore, when configured as a general purpose output pin (PTB3), a
pullup resistor must be connected to this pin.
11.8 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)
MC68HC908AP Family Data Sheet, Rev. 4
168
Freescale Semiconductor