I want to use FTM2ch3 of KEA128 to achieve PWM wave duty cycle capture.However, the frequency band that can be captured is very limited, too low frequency PWM wave can not be captured, I would like to ask you have met the same situation.The code is as follows：
void init_FTM(void) {
SIM_SCGC |= SIM_SCGC_FTM2_MASK;/* Sys Clk Gate Ctrl: enable bus clock to FTM1,2 */
/* FTM2 module settings for desired channel modes: */
FTM2_MODE |= FTM_MODE_WPDIS_MASK; /* Write protect to registers disabled (default) */
FTM2_COMBINE = 0x00000000; /* DECAPEN (Dual Edge Capture Mode Enable) = 0 */
/* COMBINE (chans n & n+1) = 0 (default; independent chans) */
FTM2_MOD = 0xFFFF;
FTM2_CNTIN = 0x01;
FTM2_SC = 0x07; /* CWMS (Center aligned PWM Select) = 0 (default, up count) */
/* TOIE (Timer Overflow Interrupt Ena) = 0 (default) */
/* CLKS (Clock source) = 0 (default, no clock; FTM disabled) */
/* PS (Prescaler factor) = 7. Prescaler = 2**7 = 128 */
}
void init_FTM2_ch3_IC(void) {
FTM2_C3SC = 0x48; /* FTM2 ch3: Input Capture on falling edge */
/* CHIE (Chan Interrupt Ena) = 0 (default) */
/* MSB:MSA (chan Mode Select) = 0b00 */
/* ELSB:ELSA (chan Edge or Level Select) = 0b01 */
SIM_PINSEL1 &= ~SIM_PINSEL1_FTM2PS3_MASK;
}
void start_FTM_counters(void) {
FTM2_SC |= FTM_SC_CLKS(1); /* Start FTM2 ctr with clk source TIMER_CLK (20 MHz)*/
}
void FTM2_IRQHandler(void)
{
FTM2_C3SC &= ~FTM_CnSC_CHF_MASK;
if(flag == 0)
{
CurrentCaptureVal1 = FTM2_C3V;
FTM2_C3SC = 0x00000048; /* FTM2 ch3: Input Capture on falling edge */
/* CHIE (Chan Interrupt Ena) = 1 (default) */
/* MSB:MSA (chan Mode Select) = 0b00 */
/* ELSB:ELSA (chan Edge or Level Select) = 0b10 */
flag = 1;
FTM2_CNT = 0x00000001;
}
else
{
CurrentCaptureVal2 = FTM2_C3V;
FTM2_C3SC = 0x00000044; /* FTM2 ch3: Input Capture on rising edge */
/* CHIE (Chan Interrupt Ena) = 1 (default) */
/* MSB:MSA (chan Mode Select) = 0b00 */
/* ELSB:ELSA (chan Edge or Level Select) = 0b01 */
flag = 0;
}
}
int main(void) {
init_clks_FEE_40MHz(); /* KEA128 clks FEE, 8MHz xtal: core 40 MHz, bus 20MHz */
init_FTM (); /* Enable bus clock to FTM1,2 prescaled by 128 */
init_FTM2_ch3_IC(); /* PTB5 input; connect J2_5 and J2_10 */
NVIC_EnableIRQ(FTM2_IRQn);
start_FTM_counters();
for (;;) {}
}
Can you help me?
