Information

Table 47-2. I
2
S signal descriptions (continued)
Signal Description I/O
SRFS Serial receive frame Sync. The SRFS port can be used as an input or
output. The frame sync is used by the receiver to synchronize the transfer
of data. The frame sync signal can be one bit or one word in length and
can occur one bit before the transfer of data or right at the transfer of data.
If SRFS is configured as an input, the external device should drive SRFS
during the rising edge of STCK or SRCK.
I/O
SRXD Serial receive data. The SRXD port is an input and is used to bring serial
data into the receive data shift register.
I
STCK Serial transmit clock. The STCK port can be used as an input or output.
This clock signal is used by the transmitter and can be continuous or
gated. During gated clock mode, data on STCK is valid only during the
transmission of data. Otherwise, it is pulled to the inactive state. In
synchronous mode, this port is used by the transmit and receive sections.
I/O
STFS Serial transmit frame sync. The STFS port can be used as an input or
output. The frame sync is used by the transmitter to synchronize the
transfer of data. The frame sync signal can be one bit or one word in
length and can occur one bit before the transfer of data or right at the
transfer of data. In synchronous mode, this port is used by both the
transmit and receive sections. In gated clock mode, frame sync signals
are not used. If STFS is configured as an input, the external device should
drive STFS during the rising edge of STCK if TSCKP is positive-edge
triggered. The external device should drive STFS during the falling edge
of STCK if TSCKP is negative-edge triggered.
I/O
STXD Serial transmit data. The STXD port is an output and transmits data from
the serial transmit shift register. The STXD port is an output port when
data is being transmitted and is disabled between data word
transmissions and on the trailing edge of the bit clock after the last bit of a
word is transmitted.
O
The following figure shows the main I
2
S configurations. These ports support all transmit
and receive functions with continuous or gated clock as shown.
Note
Gated clock implementations do not require the use of the
frame sync ports (STFS and SRFS).
I2S signal descriptions
K10 Sub-Family Reference Manual, Rev. 6, Nov 2011
1454 Freescale Semiconductor, Inc.