Serial Communications Interface Module (SCI)
I/O Registers
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Serial Communications Interface Module (SCI) 293
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the
PTE6/RxD pin is disconnected from the SCI, and the transmitter
output goes into the receiver input. Both the transmitter and the
receiver must be enabled to use loop mode. Reset clears the
LOOPS bit.
1 = Loop mode enabled
0 = Normal operation enabled
ENSCI — Enable SCI Bit
This read/write bit enables the SCI and the SCI baud rate generator.
Clearing ENSCI sets the SCTE and TC bits in SCI status register 1
and disables transmitter interrupts. Reset clears the ENSCI bit.
1 = SCI enabled
0 = SCI disabled
TXINV — Transmit Inversion Bit
This read/write bit reverses the polarity of transmitted data. Reset
clears the TXINV bit.
1 = Transmitter output inverted
0 = Transmitter output not inverted
NOTE: Setting the TXINV bit inverts all transmitted values, includ ing idle, brea k,
start, and stop bits.
M — Mode (Character Length) Bit
This read/write bit determines whether SCI characters are eight or
nine bits long. See Table 14-4. The ninth bit can serve as an extra
stop bit, as a receiver wakeup signal, or as a parity bit. Reset clears
the M bit.
1 = 9-bit SCI characters
0 = 8-bit SCI characters
Address: $0038
Bit 7654321Bit 0
Read: LOOPS ENSCI TXINV M WAKE ILTY PEN PTY
Write:
Reset:00000000
Figure 14-7. SCI Control Register 1 (SCC1)