MC68HC08AZ0 Datasheet, PDF (188/444 Pages) Motorola, Inc – Advance Information

Freescale Semiconductor, Inc.
Serial Communications Interface Module (SCI)
Table 2. SCI transmitter I/O register summary
Register Name
Bit 7 6
5
4
3
2
1 Bit 0 Addr.
SCI Control Register 1 (SCC1)LOOPS ENSCI TXINV M WAKE ILTY PEN PTY $0013
SCI Control Register 2 (SCC2) SCTIE TCIE SCRIE ILIE TE RE RWU SBK $0014
SCI Control Register 3 (SCC3) R8 T8 DMARE DMATE ORIE NEIE FEIE PEIE $0015
SCI Status Register 1 (SCS1) SCTE TC SCRF IDLE OR NF FE PE $0016
SCI Data Register (SCDR)
$0018
SCI Baud Rate Register (SCBR)
SCP1 SCP0
SCR2 SCR1 SCR0 $0019
= Unimplemented
R = Reserved
Break characters
Writing a ‘1’ to the send break bit, SBK, in SCC2 loads the transmit shift
register with a break character. A break character contains all ‘0’s and
has no start, STOP, or parity bit. Break character length depends on the
M bit in SCC1. As long as SBK is at ‘1’, transmitter logic continuously
loads break characters into the transmit shift register. After software
clears the SBK bit, the shift register finishes transmitting the last break
character and then transmits at least one ‘1’. The automatic ‘1’ at the end
of a break character guarantees the recognition of the start bit of the next
character.
The SCI recognizes a break character when a start bit is followed by
8 or 9 ‘0’ data bits and a ‘0’ where the STOP bit should be. Receiving
a break character has the following effects on SCI registers:
• Sets the framing error bit (FE) in SCS1
• Sets the SCI receiver full bit (SCRF) in SCS1
• Clears the SCI data register (SCDR)
• Clears the R8 bit in SCC3
• Sets the break flag bit (BKF) in SCS2
• May set the overrun (OR), noise flag (NF), parity error (PE), or
reception in progress flag (RPF) bits
MC68HC08AZ0
186
Serial Communications Interface Module (SCI)
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