SYNCHRONOUS SERIAL INTERFACE (SSI)
6 - 130
PORT C
MOTOROLA
6.4.7.2.1
Normal Mode Transmit
The conditions for data transmission from the SSI are as follows:
1. Transmitter is Enabled (TE=1)
2. Frame sync (or clock in gated clock mode) is active
When these conditions occur in normal mode, the next data word will be transferred from
TX to the transmit shift register, the TDE flag will be set (transmitter empty), and the trans-
mit interrupt will occur if TIE equals one (transmit interrupt enabled.) The new data word
will be transmitted immediately.
The transmit data output (STD) is three-stated, except during the data transmission peri-
od. The optional frame sync output, flag outputs, and clock outputs are not three-stated
even if both receiver and transmitter are disabled.
The optional output flags are always updated at the beginning of the frame, regardless of
TE. The state of the flag does not change for the entire frame.
DSP DATA
DSP DATA
SERIAL CLOCK
SERIAL SYNC
TRANSMIT DATA
CODEC DATA
RECEIVE DATA
MC1550x
CODEC FILTER
DSP56002
TDD
RDD
TDC
RDC
TDE
RCE
MSI
TX1
RX0
SRD
STD
SCK
SC2
ANALOG
INPUT
ANALOG
OUTPUT
CODEC DATA
Figure 6-72 Normal Mode Example
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Freescale Semiconductor, Inc.
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