Freescale Semiconductor MC68HC908MR32 - Manual (Page 169)

I/O Registers
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 169
13.6.2 PTF4/RxD (Receive Data)
The PTF4/RxD pin is the serial data input to the SCI receiver. The SCI shares the PTF4/RxD pin with
port F. When the SCI is enabled, the PTF4/RxD pin is an input regardless of the state of the DDRF4 bit
in data direction register F (DDRF).
13.7 I/O Registers
These I/O registers control and monitor SCI operation:
• SCI control register 1 (SCC1)
• SCI control register 2 (SCC2)
• SCI control register 3 (SCC3)
• SCI status register 1 (SCS1)
• SCI status register 2 (SCS2)
• SCI data register (SCDR)
• SCI baud rate register (SCBR)
13.7.1 SCI Control Register 1
SCI control register 1 (SCC1):
• Enables loop-mode operation
• Enables the SCI
• Controls output polarity
• Controls character length
• Controls SCI wakeup method
• Controls idle character detection
• Enables parity function
• Controls parity type
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the PTF4/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
Address: $0038
Bit 7 6 5 4 3 2 1 Bit 0
Read:
LOOPS ENSCI TXINV M WAKE ILTY PEN PTY
Write:
Reset: 0 0 0 0 0 0 0 0
Figure 13-8. SCI Control Register 1 (SCC1)