Freescale Semiconductor, Inc.
Serial Communications Interface (SCI)
10.6.2 SCI Control Register 1
SCI control register 1 (SCCR1) shown in Figure 10-6 has these
functions:
• Stores ninth SCI data bit received and ninth SCI data bit
transmitted
• Controls SCI character length
• Controls SCI wakeup method
Address: $000E
Bit 7
R8
U
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
T8
U
M
U
WAKE
U
= Unimplemented
U = Unaffected
Figure 10-6. SCI Control Register 1 (SCCR1)
R8 — Bit 8 (Received)
When the SCI is receiving 9-bit characters, R8 is the ninth bit of the
received character. R8 receives the ninth bit at the same time that the
SCDR receives the other eight bits. Reset has no effect on the R8 bit.
T8 — Bit 8 (Transmitted)
When the SCI is transmitting 9-bit characters, T8 is the ninth bit of the
transmitted character. T8 is loaded into the transmit shift register at
the same time that SCDR is loaded into the transmit shift register.
Reset has no effect on the T8 bit.
M — Character Length Bit
This read/write bit determines whether SCI characters are eight or
nine bits long. The ninth bit can be used as an extra stop bit, as a
receiver wakeup signal, or as a mark or space parity bit. Reset has no
effect on the M bit.
1 = 9-bit SCI characters
0 = 8-bit SCI characters
Technical Data
130
MC68HC705C8A — Rev. 3
Serial Communications Interface (SCI)
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