MC68HC705MC4 Datasheet, PDF (82/99 Pages) Motorola, Inc – Microcontrollers

MC68HC705MC4 Specification Rev. 1.5
10.5 SCI I/O REGISTERS
The following I/O registers control and monitor SCI operation:
• SCI Data Register (SCDR)
• SCI Control Register 1 (SCCR1)
• SCI Control Register 2 (SCCR2)
• SCI Status Register (SCSR)
10.5.1 SCI Data Register (SCDR)
The SCI data register is the buffer for characters received and for characters transmitted.
SCDR
$000E
READ:
WRITE:
RESET:
7
6
5
4
3
2
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2
UNAFFECTED BY RESET
Figure 10-4: SCI Data Register (SCDR)
1
BIT 1
0
BIT 0
10.5.2 SCI Control Register 1 (SCCR1)
SCI control register 1 has the following functions:
• Stores ninth SCI data bit received and ninth SCI data bit transmitted
• Controls SCI character length
• Controls SCI wakeup method
7
6
5
4
3
2
1
0
SCCR1
$000B
READ
WRITE
R8
T8
M WAKE
RESET:
UNAFFECTED BY RESET
Figure 10-5: 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
Section 10: Serial Communications Interface
MOTOROLA
Page 73