MC68HC908AS60ACFN FREESCALE [Freescale Semiconductor, Inc], MC68HC908AS60ACFN Datasheet - Page 182

• Manufacturer Part Number: MC68HC908AS60ACFN
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Serial Communications Interface (SCI)
18.4.2.3 Break Characters
Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit shift register with a break
character. A break character contains all logic 0s and has no start, stop, or parity bit. Break character
length depends on the M bit in SCC1. As long as SBK is at logic 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 eight or nine logic 0 data bits and a
logic 0 where the stop bit should be. Receiving a break character has the following effects on SCI
registers:
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SCI Baud Rate Register (SCBR)
SCI Status Register 1 (SCS1)
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
Register Name
SCI Data Register (SCDR)
Register
Address
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
Figure 18-5. SCI Transmitter I/O Register Summary (Continued)
Table 18-3. SCI Transmitter I/O Address Summary
Reset:
Reset:
Reset:
Read:
Read:
Read:
SCC1
$0013
Write:
Write:
Write:
SCTE
Bit 7
R7
T7
1
0
0
SCC2
$0014
= Unimplemented
TC
R6
T6
6
1
0
0
SCC3
$0015
SCRF
SCP1
R5
T5
5
0
0
$0016
SCS1
U = Unaffected
Unaffected by Reset
SCP0
IDLE
R4
T4
4
0
0
SCDR
$0018
OR
R3
T3
R
3
0
0
R = Reserved
SCR2
SCBR
$0019
NF
R2
T2
2
0
0
Freescale Semiconductor
SCR1
FE
R1
T1
1
0
0
SCR0
Bit 0
PE
R0
T0
0
0