CS18101X datasheet(36/54 Pages) CIRRUS

36 / 54 page

DS651UM23

Version 2.3

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 */

}

CS18101X Datasheet(PDF) 36 Page - Cirrus Logic