AN1105 datasheet(34/100 Pages) STMICROELECTRONICS

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ST7 pCAN PERIPHERAL DRIVER

CAN_Buffer periodic_transmission;

In the TIMA_Init() function, make sure the following lines are included:

TACR1=0x40

TACR2=0x08

TAOC1HR=0x3A

TAOC1LR=0x98

and finally,

#asm

LD _TAOC2HR,A; /* Write the Output Compare 2 high register to disable the OC2 */

LD A,_TASR

/* Clear the flags in case it is already set. To Clear

LD A,_TAOC1LR

/* OC1F flag: Read Status Register and Access OC1R low byte,

clearing OC1F flag */

LD A,_TAOC2LR

/* OC2F flag: Read Status Register and Access OC2R low

byte,clearing OC2F flag*/

LD _TAOC2HR,A//No access to low byte: OutputCompare 2 ITs disabled

#endasm

Note: The explanation of the code written here concerns timer programming and is beyond the scope of

this document. Its purpose is to configure timer A to trigger a timer interrupt every 15 ms. Further

explanations of timer functions can be found in the microcontroller datasheet.

Then we have to fill in the IT function of the timer:

void TIMA_Interrupt(void)

{

u16 output_value;

if (ValBit(TASR,OCF1))

{

TASR;

output_value = ((unsigned int)TAOC1HR << 8)| TAOC1LR;

}

output_value += 0x3A98;

TAOC1HR = output_value >>8;

TAOC1LR = (unsigned char) output_value;

//Note: The code above is only meant to update the value for the next IT

//Now comes the code that interests us

if (!periodic_transmission.message_in_queue) //Checks if the message is already

//in the transmission queue

{

periodic_transmission.msg_identifier=0x4020;

periodic_transmission.data_size=DLC1;

periodic_transmission.CAN_Msg_data[0]=ADC_Get(0x00);

AN1105 Datasheet(PDF) 34 Page - STMicroelectronics

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