MC9S08GB60 Datasheet, PDF (184/290 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface (SCI) Module
RAF — Receiver Active Flag
RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is cleared
automatically when the receiver detects an idle line. This status flag can be used to check whether an
SCI character is being received before instructing the MCU to go to stop mode.
1 = SCI receiver active (RxD1 input not idle).
0 = SCI receiver idle waiting for a start bit.
11.10.6 SCI x Control Register 3 (SCIxC3)
Bit 7
6
5
4
3
2
1
Bit 0
Read: R8
Write:
0
T8
TXDIR
ORIE NEIE FEIE PEIE
Reset: 0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-11. SCI x Control Register 3 (SCIxC3)
R8 — Ninth Data Bit for Receiver
When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a ninth receive data bit to
the left of the MSB of the buffered data in the SCIxD register. When reading 9-bit data, both R8 and
SCIxD must be read to complete the automatic RDRF clearing sequence.
T8 — Ninth Data Bit for Transmitter
When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a ninth transmit data bit
to the left of the MSB of the data in the SCIxD register. When writing 9-bit data, the entire 9-bit value
is transferred to the SCI shift register after SCIxD is written so T8 should be written (if it needs to
change from its previous value) before SCIxD is written. If T8 does not need to change in the new
value (such as when it is used to generate mark or space parity), it need not be written each time SCIxD
is written.
TXDIR — TxD1 Pin Direction in Single-Wire Mode
When the SCI is configured for single-wire half-duplex operation (LOOPS = RSRC = 1), this bit
determines the direction of data at the TxD1 pin.
1 = TxD1 pin is an output in single-wire mode.
0 = TxD1 pin is an input in single-wire mode.
ORIE — Overrun Interrupt Enable
This bit enables the overrun flag (OR) to generate hardware interrupt requests.
1 = Hardware interrupt requested when OR = 1.
0 = OR interrupts disabled (use polling).
MC9S08GB/GT Data Sheet, Rev. 2.3
184
Freescale Semiconductor