Posted on May 17, 2011 at 11:35Hi there!
i've got a problem with the MFT0.
i just want to measure the duration auf a signal, which comes about 50times a second.
the MFT0 is programmed with:
trigger on T0INA, Clear on Capture, IT for Capture enabled.
DMA not enabled.
But the Capture-IT will be called to often, while the Capture-Event occures rare.
when the capture occures, the count-value is ok, when no signal is connected, the overflow-IT occures - this is all correct so far.
but why is the capture-IT called so often, with no Flag (T_FLAGR & Tm_cp0) set?
I don't know were the problem is.
can anybody help me?
thanks.
siggi
----------------------- here is the listing: --------------------------- snip
void INIT_MFT(void)
{
// Disable IT
di();
spp(T0D_PG);
T_PRSR =2; // Value of the prescaler
T_REG0R = 0x8000; // Initial value of the counter
T_REG1R = 0x8000;
T_TCR = Tm_ccp0 | Tm_udc; // Clear on Capture, Direction=Up
T_TMR = Tm_rm0 | Tm_ren; // Capture on REG0R, Disable Retrigger
T_ICR = Tm_exa_r | Tm_ab_ti; // TxINA=rising, Function=Trigger / IO
T_OACR = bin(1,1,1,1,1,1,0,0); // Disable Outputs
T_OBCR = bin(1,1,1,1,1,1,0,0);
T_CMP0R = 0xf000; /* Initial value of Compare0 register */
T_CMP1R = 0xf000; /* Initial value of Compare1 register */
// Init II
spp(T0C_PG);
T0_IVR = 0x40; // IT vector
T0_IDCR = 0; // Set priority
spp(T0D_PG);
T_IDMR = Tm_gtien | Tm_cp0i | Tm_oui; // Global IT mask for the MFT
T_FLAGR = 0; // clear previous requests (=errors)
ei();
// Start MFT
T_TCR |= Tm_cen;
}
#pragma INTERRUPT INT_MFT0_OVER 10
void INT_MFT0_OVER(void) {
debug2++;
spp(T0D_PG);
T_FLAGR &= ~Tm_ouf;
};
#pragma INTERRUPT INT_MFT0_CAPT 11
void INT_MFT0_CAPT(void) {
spp(T0D_PG);
if ( (T_FLAGR & Tm_cp0)==Tm_cp0 ) {
// Capture 0 occured
debug3++;
count[index]=T_REG0R;
index++;
if (index > 4) index=0;
T_FLAGR &= ~Tm_cp0;
} else {
// Anything else occured !?
debug4++;
};
};
