SYNCHRONOUS SERIAL INTERFACE (SSI)
MOTOROLA
PORT C
6 - 141
Figure 6-78 differs from the program shown in Figure 6-73 only in that it uses the network
mode to transmit only right-channel data. A time slot is assigned for the left-channel data,
which could be inserted by another DSP using the network mode. In the “Initialize SSI
Port” section of the program, two words per frame are selected using CRA, and the net-
work mode is selected by setting MOD to one in the CRB. The main interrupt routine,
which waits to move the data to TX, only transmits data if the current time slot is for the
right channel. If the current time slot is for the left channel, the TSR is written, which
three-states the output to allow another DSP to transmit the left channel during the time
slot.
;*************************************************
;
SSI and other I/O EQUATES
*
;*************************************************
IPR
EQU
$FFFF
CRA
EQU
$FFEC
CRB
EQU
$FFED
PCC
EQU
$FFE1
TX
EQU
$FFEF
TSR
EQU
$FFEE
FLG
EQU
$0010
ORG
X:0
DC
$AAAA00
;Data to transmit.
DC
$333300
DC
$CCCC00
DC
$F0F000
;*************************************************
;
INTERRUPT VECTOR
*
;*************************************************
ORG
P:$0010
JSR
XMT
;*************************************************
;
MAIN PROGRAM
*
;*************************************************
ORG
P:$40
MOVE
#0,R0
;Pointer to data buffer.
MOVE
#3,M0
;Set modulus to 4.
MOVE
#0,X0
;Initialize user flag for SSI flag.
MOVE
X0,X:FLG
;Start with the right channel.
Figure 6-78 Network Mode Transmit Example Program (Sheet 1 of 2)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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