MC68HC908MR8 Datasheet, PDF (269/372 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface (SCI)
I/O Registers
NOTE: Writing to the RE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RWU — Receiver Wakeup Bit
This read/write bit puts the receiver in a standby state during which
receiver interrupts are disabled. The WAKE bit in SCC1 determines
whether an idle input or an address mark brings the receiver out of the
standby state and clears the RWU bit. Reset clears the RWU bit.
1 = Standby state
0 = Normal operation
SBK — Send Break Bit
Setting and then clearing this read/write bit transmits a break
character followed by a logic 1. The logic 1 after the break character
guarantees recognition of a valid start bit. If SBK remains set, the
transmitter continuously transmits break characters with no logic 1s
between them. Reset clears the SBK bit.
1 = Transmit break characters
0 = No break characters being transmitted
NOTE:
Do not toggle the SBK bit immediately after setting the SCTE bit.
Toggling SBK too early causes the SCI to send a break character
instead of a preamble.
13.9.3 SCI Control Register 3
SCI control register 3 (SCC3):
• Stores the ninth SCI data bit received and the ninth SCI data bit to
be transmitted
• Enables SCI receiver full (SCRF)
• Enables SCI transmitter empty (SCTE)
• Enables the following interrupts:
– Receiver overrun interrupts
– Noise error interrupts
– Framing error interrupts
– Parity error interrupts
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Serial Communications Interface (SCI)
Technical Data
269