mc9s08ac16 Freescale Semiconductor, Inc, mc9s08ac16 Datasheet - Page 201

• Manufacturer Part Number: mc9s08ac16
• Description: Hcs08 Microcontrollers 8-bit Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

11.2.4
This register has eight read-only status flags. Writes have no effect. Special software sequences (which do
not involve writing to this register) are used to clear these status flags.
Freescale Semiconductor
Reset
Field
RWU
SBK
RE
TE
3
2
1
0
W
R
TDRE
SCI Status Register 1 (SCIxS1)
Transmitter Enable
0 Transmitter off.
1 Transmitter on.
TE must be 1 in order to use the SCI transmitter. When TE = 1, the SCI forces the TxD pin to act as an output
for the SCI system.
When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the direction of
traffic on the single SCI communication line (TxD pin).
TE also can be used to queue an idle character by writing TE = 0 then TE = 1 while a transmission is in progress.
Refer to
When TE is written to 0, the transmitter keeps control of the port TxD pin until any data, queued idle, or queued
break character finishes transmitting before allowing the pin to revert to a general-purpose I/O pin.
Receiver Enable — When the SCI receiver is off, the RxD pin reverts to being a general-purpose port I/O pin.
If LOOPS = 1 the RxD pin reverts to being a general-purpose I/O pin even if RE = 1.
0 Receiver off.
1 Receiver on.
Receiver Wakeup Control — This bit can be written to 1 to place the SCI receiver in a standby state where it
waits for automatic hardware detection of a selected wakeup condition. The wakeup condition is either an idle
line between messages (WAKE = 0, idle-line wakeup), or a logic 1 in the most significant data bit in a character
(WAKE = 1, address-mark wakeup). Application software sets RWU and (normally) a selected hardware
condition automatically clears RWU. Refer to
0 Normal SCI receiver operation.
1 SCI receiver in standby waiting for wakeup condition.
Send Break — Writing a 1 and then a 0 to SBK queues a break character in the transmit data stream. Additional
break characters of 10 or 11 (13 or 14 if BRK13 = 1) bit times of logic 0 are queued as long as SBK = 1.
Depending on the timing of the set and clear of SBK relative to the information currently being transmitted, a
second break character may be queued before software clears SBK. Refer to
Queued
0 Normal transmitter operation.
1 Queue break character(s) to be sent.
1
7
Section 11.3.2.1, “Send Break and Queued
Idle” for more details.
= Unimplemented or Reserved
TC
1
6
Table 11-4. SCIxC2 Field Descriptions (continued)
Figure 11-8. SCI Status Register 1 (SCIxS1)
MC9S08AC16 Series Data Sheet, Rev. 0
RDRF
0
5
PRELIMINARY
IDLE
Section 11.3.3.2, “Receiver Wakeup
0
4
Description
Idle” for more details.
Chapter 11 Serial Communications Interface (S08SCIV4)
OR
3
0
NF
0
2
Section 11.3.2.1, “Send Break and
Operation” for more details.
FE
0
1
PF
0
0
201