The SPI Function - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 497

PTM | 5 BIT1; // enable TC72 data transfer

putcspi0(0x02); // send MSB temperature read address

hi_byte 5 getcspi0(); // read the temperature high byte

lo_byte 5 getcspi0(); // save the temperature low byte and clear SPIF

PTM & 5 , BIT1; // disable TC72 data transfer

lo_byte & 5 0xC0; // make sure the lower 6 bits are 0s

result 5 (int)hi_byte * 256 1 (int)lo_byte;

if (hi_byte & 0x80) { // temperature is negative

result 5 2 result; // take the two's complement of result

result ..5 6;

temp 5 result & 0x0003; // place the lowest 2 bits in temp

result ..5 2; // get rid of fractional part

*ptr 115 0x2D; // store the minus sign

int2alpha(result, ptr);

}

else { // temperature is positive

result ..5 6;

temp 5 result & 0x0003; // save fractional part

result ..5 2; // get rid of fractional part

int2alpha(result, ptr); // convert to ASCII string

}

while(*bptr){ // search the end of the string

bptr 11 ;

};

switch (temp){ // add fractional digits to the temperature

case 0:

break;

case 1: // fractional part is 25

*bptr 115 0x2E; // add decimal point

*bptr 115 0x32;

*bptr 115 0x35;

*bptr 5 '\0';

break;

case 2: // fractional part is 5

*bptr 115 0x2E; // add decimal point

*bptr 115 0x35;

*bptr 5 '\0';

break;

case 3: // fractional part is 75

*bptr 115 0x2E; // add decimal point

*bptr 115 0x37;

*bptr 115 0x35;

*bptr 5 '\0';

break;

default:

break;

}

}

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