Sci Status Register 1 (Scix_S1) - NXP Semiconductors MC9S08SU16 Reference Manual

Register definition
Field
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 Send Break
SBK
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.

22.4.5 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: 1868h base + 4h offset = 186Ch
Bit 7
Read TDRE
Write
Reset
1
Field
7 Transmit Data Register Empty Flag
TDRE
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 Transmission Complete Flag
TC 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]
404
SCIx_C2 field descriptions (continued)
6 5
TC RDRF IDLE
1 0
SCIx_S1 field descriptions
Table continues on the next page...
MC9S08SU16 Reference Manual, Rev. 5, 4/2017
Description
4 3
OR NF
0 0
Description
2 1
FE PF
0 0
NXP Semiconductors
0
0