Renesas SH7781 - Manual (Page 1342)

26. Serial Sound Interface (SSI) Module
Rev.1.00 Jan. 10, 2008 Page 1312 of 1658
REJ09B0261-0100
Bit Bit Name
Initial
Value R/W Description
1 SWNO 1 R Serial Word Number
The number indicates the current word number.
When TRMD = 0 (Receive Mode):
This bit indicates which system word the current data in
SSIRDR is. Regardless whether the data has been read
out from SSIRDR, when the data in SSIRDR is updated
by transfer from the shift register, this value will change.
When TRMD = 1 (Transmit Mode):
This bit indicates which system word should be written
in SSITDR. When data is copied to the shift register,
regardless whether the data is written in SSITDR, this
value will change.
0 IDST 1 R Idle Mode Status Flag
Indicates that the serial bus activity has ceased.
This bit is cleared if EN = 1 and the serial bus is
currently active.
This bit can be set to 1 automatically under the
following conditions.
SSI = Serial bus master transmitter (SWSD = 1 and
TRMD = 1):
This bit is set to 1 if no more data has been written to
SSITDR and the current system word has been
completed. It can also be set to 1 when the EN bit has
been cleared and the data that has been written to
SSITDR is output on the serial data input/output pin
(SSI_SDATA), i.e., the serial data of the system word
length is output.
SSI = Serial bus master receiver (SWSD = 1 and TRMD
= 0):
This bit is set to 1 if the EN bit is cleared and the current
system word is completed.
SSI = slave transmitter/ receiver (SWSD = 0):
This bit is set to 1 if the EN bit is cleared and the current
system word is completed.
Note that when transmitting the data transmission in
slave mode, the WS signal should be input until
SSICR.IDST becomes 1 after SSICR.EN is cleared to
0.
Note: If the external device stops the serial bus clock
before the current system word is completed
then this bit will never be set.
Note: * These bits are readable/writable bits. If writing 0, these bits are initialized, although
writing 1 is ignored.