Posted on October 18, 2004 at 12:52Hi! Does anybody knows / has an exapmle for using one of the timer as a counter without using the GPIO. Just initialize the timer, set an external variable to a specific value wich will be counted down/up by the interruptroutine. In my program, i use the timer just as a counter but
my main problem is the prescalervalue. I can change it between 0xf and 0xf0 and the time between 2 interrupts will change from 31 microseconds to 148 microsecond. This seems to be very short. I would like to have times around 10-100 milliseconds between an interrupt. So, perhaps i have something forgotten to initialize and somebody has a suggestion?
hein_b
void start_time1(ushort x_in_sek)
{
u32 sekundenfaktor=1; // 10
timer1_cnt = 0x1*sekundenfaktor*x_in_sek; // 0x300 *...
Myprescaler1=0x50;
// just for time-measurements (not necessary for real program)
// Configure Port 2 pins
GPIO_Config (GPIO0, 0xFFFF, GPIO_OUT_PP);
GPIO0->PD = 0x0000;
// Initialize the Timer
TIM_Init ( TIM1 );
//---------------------------------------------------------------------------
// Configure the EIC Timer1 IRQ channel
//---------------------------------------------------------------------------
EIC_IRQChannelConfig( T1TIMI_IRQChannel, ENABLE );
EIC_IRQChannelPriorityConfig( T1TIMI_IRQChannel , 1);
EIC_IRQConfig( ENABLE );
// Configure the TIM Prescaler
TIM_PrescalerConfig ( TIM1, Myprescaler1 );
// Enable the OverFlow Interrupt
TIM_ITConfig ( TIM1 , TIM_TO_IT , ENABLE );
TIM_CounterConfig ( TIM1, TIM_START );
// own flags
timer1_fin = 0; // ;timer ist noch nicht abgelaufen
timer1_run = 1; // ;timer laeuft
time_out = 0;
return;
}
// routine, called by the interruptprogram
void cnt_dwn1()
{
if (timer1_run==1) // und der timer laeuft
{
if (timer1_cnt > 0) // und noch nicht abgelaufen ist
{
timer1_cnt -=1; // dann einen runterzaehlen
// GPIO0->PD = ~GPIO0->PD; //just for time measurement
}
else
{
time_out = 1; // sonst time_out flag setzen!
}
}
}
