Motorola DSP56012 - Manual (Page 198)

6-20 DSP56012 User’s Manual MOTOROLA
Serial Audio Interface
Serial Audio Interface Programming Model
6.3.4.9 TCS Transmitter Relative Timing (TREL)—Bit 9
The read/write Transmitter Relative timing (TREL) control bit selects the relative
timing of the WST signal in reference to the serial data output lines (SDOx). When
TREL is cleared, the transition of WST, indicating the start of a data word, occurs
together with the first bit of that data word. When TREL is set, the transition of WST
occurs one serial clock cycle earlier (together with the last bit of the previous data
word), as required by the I
2
S format (see Figure 6-13).The TREL bit is cleared during
hardware reset and software reset.
6.3.4.10 TCS Transmitter Data Word Expansion (TDWE)—Bit 10
The read/write Transmitter Data Word Expansion (TDWE) control bit selects the
method used to expand a 24-bit data word to 32 bits during transmission. When
TDWE is cleared, after transmitting the 24-bit data word from the transmit data
Figure 6-12 Transmitter Clock Polarity (TCKP) Programming
Figure 6-13 Transmitter Relative Timing (TREL) Programming
SDO
SCKT
TCKP = 0
SDO
SCKT
TCKP = 1
WST WST
AA0438k
MSB LSB LSB MSB
SDO
WST
MSB
Left
Right
MSB LSB LSB MSB
SDO
WST
MSB
Left
Right
LSB
TREL = 0
TREL = 1
AA0439