CobraNet Hardware User’s Manual
HMI Reference Code
8.3 CM-1, CM-2 Auto-detection
The following function is useful for systems that support both the CM-1 and CM-2 or
where a CobraNet interface is an optional add-in.
Detect() returns 0 if no CobraNet interface module is detected, 1 for CM-1 and 2 for CM-2.
int Detect( void ) {
/* check for presence of CM-1 */
MSG_B = 0x55; /* write to CM-1 CVR register */
DATA_A = 0xaa; /* write to unused CM-1 register to flip data bus */
if( MSG_B == 0x55 ) { /* read back CVR */
/* redo same detection with different data */
MSG_B = 0x3c;
DATA_A = 0xc3;
if( MSG_B == 0x3c ) {
return 1; /* CM-1 detected */
}
}
/* check for presence of CM-2 */
/* issue identify command */
MSG_C = MOP_IDENTIFY;
MSG_D = CVR_MULTIPLEX_OP;
int msgack = MSG_D; /* clean pipeline */
msgack = MSG_D;
/* wait for togglebit to flip in response to command */
int tm0 = gettimeofday();
while( !( ( MSG_D ^ toggle ) & ( 1 << MSG_TOGGLE_BO ) ) ) {
int tm1 = gettimeofday();
if( ( tm1 - tm0 ) > time_out ) {
return 0; /* command timed out, no CobraNet interface present */
}
}
int garbage = MSG_D; /* clean pipeline */
/* verify identify results */
if( DATA_A == 'C' ) if( DATA_B == 'S' )
if( DATA_C == ( 18101 >> 8 ) ) if( DATA_D == ( 18101&0xff ) {
return 2; /* CM-2 detected */
}
return 0; /* no interface or non-supported interface */
}
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