SCIx_C2 field descriptions (continued)
Field
Description
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 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.
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 or 12, 13 or 14 or 15 if BRK13 = 1, bit times of logic 0 are queued as long as SBK is
set. 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.
0
Normal transmitter operation.
1
Queue break character(s) to be sent.
14.3.5 SCI Status Register 1 (SCIx_S1)
This register has eight read-only status flags. Writes have no effect. Special software
sequences, which do not involve writing to this register, clear these status flags.
Address: 3080h base + 4h offset = 3084h
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
1
1
0
0
0
0
0
0
SCIx_S1 field descriptions
Field
Description
7
TDRE
Transmit Data Register Empty Flag
TDRE is set out of reset and when a transmit data value transfers from the transmit data buffer to the
transmit shifter, leaving room for a new character in the buffer. To clear TDRE, read SCI_S1 with TDRE
set and then write to the SCI data register (SCI_D).
0
Transmit data register (buffer) full.
1
Transmit data register (buffer) empty.
6
TC
Transmission Complete Flag
TC is set out of reset and when TDRE is set and no data, preamble, or break character is being
transmitted.
TC is cleared automatically by reading SCI_S1 with TC set and then doing one of the following:
• Write to the SCI data register (SCI_D) to transmit new data
• Queue a preamble by changing TE from 0 to 1
• Queue a break character by writing 1 to SCI_C2[SBK]
Table continues on the next page...
Chapter 14 Serial communications interface (SCI)
MC9S08PA4 Reference Manual, Rev. 5, 08/2017
NXP Semiconductors
277
Summary of Contents for MC9S08PA4
Page 1: ...MC9S08PA4 Reference Manual Supports MC9S08PA4 Document Number MC9S08PA4RM Rev 5 08 2017 ...
Page 2: ...MC9S08PA4 Reference Manual Rev 5 08 2017 2 NXP Semiconductors ...
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Page 28: ...System clock distribution MC9S08PA4 Reference Manual Rev 5 08 2017 28 NXP Semiconductors ...
Page 150: ...Port data registers MC9S08PA4 Reference Manual Rev 5 08 2017 150 NXP Semiconductors ...
Page 196: ...Human machine interfaces HMI MC9S08PA4 Reference Manual Rev 5 08 2017 196 NXP Semiconductors ...
Page 224: ...Instruction Set Summary MC9S08PA4 Reference Manual Rev 5 08 2017 224 NXP Semiconductors ...
Page 232: ...Functional Description MC9S08PA4 Reference Manual Rev 5 08 2017 232 NXP Semiconductors ...
Page 258: ...FTM Interrupts MC9S08PA4 Reference Manual Rev 5 08 2017 258 NXP Semiconductors ...
Page 294: ...Functional description MC9S08PA4 Reference Manual Rev 5 08 2017 294 NXP Semiconductors ...
Page 398: ...Resets MC9S08PA4 Reference Manual Rev 5 08 2017 398 NXP Semiconductors ...
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