Freescale Semiconductor HCS08 Series, Reference Manual

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Serial Communications Interface (S08SCIV4)
MC9S08JS16 MCU Series Reference Manual, Rev. 4
Freescale Semiconductor 175
12.2.4 SCI Status Register 1 (SCIS1)
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.
2
RE
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.
1
RWU
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
Section 12.3.3.2, “Receiver Wakeup Operation ” for more details.
0 Normal SCI receiver operation.
1 SCI receiver in standby waiting for wakeup condition.
0
SBK
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
Section 12.3.2.1, “Send Break and
Queued Idle ” for more details.
0 Normal transmitter operation.
1 Queue break character(s) to be sent.
7 6 5 4 3 2 1 0
R TDRE TC RDRF IDLE OR NF FE PF
W
Reset 1 1 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 12-8. SCI Status Register 1 (SCIS1)
Table 12-4. SCIC2 Field Descriptions (continued)
Field Description