Page 296 - Programming Microcontrollers in C

Timer Operations 281

PWM_count= ((motor_speed+12528)/63)*8;
PWM_count=limit(PWM_count);
}
if(tick)
{
tick=FALSE;
delpc=(3809500lu/motor_period);
delpc=delpc*(motor_period-
measured_period)/motor_period;
PWM_count -=delpc;
PWM_count=limit(PWM_count);
rpm=30000000L/measured_period;
}
/* input the new motor speed */
/* Send out the measured RPM to the terminal
periodically */
if(tick1&&!in_process)
{
tick1=FALSE;
rpm=30000000L/measured_period;
dprint(rpm);
do_crlf();
}

if (SCSR.RDRF==ON) /* read in data if it is
there */
{
in_process=TRUE;
new_character=SCDR; /* get new byte and
save it */
while(SCSR.TDRE==OFF); /* wait until transmit
buffer is empty */
SCDR=new_character; /* send out byte and
reset TDRE */
/* got a number, process it */
if(new_character>=’0' && new_character <=’9')
new_speed = 10*new_speed + new_character-‘0’;
else if(new_character==’\r’)