Inter-Integrated Circuit (I2C) Interface - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 572

To confi gure the DS1631A with the desired setting, use the following instruction sequence to
call the previous function:
ldab #$0E
jsr openDS1631
The C language version of the function is as follows:
char openDS1631(char cy)
{

sendSlaveID(0x92); /* generate a start condition and send ID */

if (IBSR & RXAK)

return 2 1; /* error code when DS1631A did not acknowledge */

IBDR 5 0xAC; /* send command Access Config */

while(!(IBSR & IBIF));

IBSR 5 IBIF; /* clear the IBIF flag */

if (IBSR & RXAK)

return 2 1; /* error code when DS1631A did not acknowledge */

IBDR 5 cy; /* send configuration byte */

while(!(IBSR & IBIF));

IBSR 5 IBIF;

if (IBSR & RXAK)

return 2 1; /* error code when DS1631A did not acknowledge */

IBCR & 5 , MSSL; /* generate a stop condition */

return 0; /* normal return code */

}

▲

Example 11.11
▼

Write a function to start temperature conversion.
Solution: The procedure for starting temperature conversion using the DS1631A is as follows:
Step 1
Assert a start condition and send a control byte (0x92) to the DS1631A with R/W 5 0.
Step 2
Wait until the I 2 C bus is idle and check to see if the DS1631A acknowledges. If not, exit.
Step 3
Send a Start Convert T command to the DS1631A.
Step 4
Wait until the I 2 C transfer is completed and check to see if the DS1631A acknowledges.
If not, exit.
Step 5
Assert a stop condition to complete the whole process.
The assembly program that implements this procedure is as follows:
startConv

ldaa #$92

jsr sendSlaveID ; generate a start condition and send DS1631A's ID

brclr IBSR,RXAK,startOK0 ; did DS1631A acknowledge?

ldab #$FF ; return error code 2 1

rts