I have completed a PWM code with a duty ratio of 1KHz and 0.5D.
And I adjusted the cnv value between 0 and 8000 because I wanted to adjust D.
But it worked contrary to what I thought.
From the FTM0 Initialization function: I wanted 0.1 duty for 800cnv based on 8,000tick.
However, the results showed a waveform of 0.9D.
Why does this result come out even though it's in low true mode?
How should I solve this in order to do it the way I want?
I am attaching my code at the bottom.
=======================================================================
#include "device_registers.h"
#include "clocks_and_modes.h"
int lpit0_ch0_flag_counter = 0; /*< LPIT0 timeout counter */
void LPIT0_init (uint32_t delay)
{
uint32_t timeout;
/*!
* LPIT Clocking:
* ==============================
*/
PCC->PCCn[PCC_LPIT_INDEX] = PCC_PCCn_PCS(6); /* Clock src=6 (SPLL2_DIV2_CLK)*/
PCC->PCCn[PCC_LPIT_INDEX] |= PCC_PCCn_CGC_MASK; /* Enable clk to LPIT0 regs */
/*!
* LPIT Initialization:
*/
LPIT0->MCR |= LPIT_MCR_M_CEN_MASK; /* DBG_EN-0: Timer chans stop in Debug mode */
/* DOZE_EN=0: Timer chans are stopped in DOZE mode */
/* SW_RST=0: SW reset does not reset timer chans, regs */
/* M_CEN=1: enable module clk (allows writing other LPIT0 regs) */
timeout=delay* 40;
LPIT0->TMR[0].TVAL = timeout; /* Chan 0 Timeout period: 40M clocks */
LPIT0->TMR[0].TCTRL |= LPIT_TMR_TCTRL_T_EN_MASK;
/* T_EN=1: Timer channel is enabled */
/* CHAIN=0: channel chaining is disabled */
/* MODE=0: 32 periodic counter mode */
/* TSOT=0: Timer decrements immediately based on restart */
/* TSOI=0: Timer does not stop after timeout */
/* TROT=0 Timer will not reload on trigger */
/* TRG_src=0: External trigger soruce */
/* TRG_SEL=0: Timer chan 0 trigger source is selected*/
}
void delay_us (volatile int us){
LPIT0_init(us); /* Initialize PIT0 for 1 second timeout */
while (0 == (LPIT0->MSR & LPIT_MSR_TIF0_MASK)) {} /* Wait for LPIT0 CH0 Flag */
lpit0_ch0_flag_counter++; /* Increment LPIT0 timeout counter */
LPIT0->MSR |= LPIT_MSR_TIF0_MASK; /* Clear LPIT0 timer flag 0 */
}
void FTM_init (void){
//FTM0 clocking
PCC->PCCn[PCC_FTM0_INDEX] &= ~PCC_PCCn_CGC_MASK; //Ensure clk diabled for config
PCC->PCCn[PCC_FTM0_INDEX] |= PCC_PCCn_PCS(0b010) //Clocksrc=1, 8MHz SIRCDIV1_CLK
| PCC_PCCn_CGC_MASK; //Enable clock for FTM regs
//FTM0 Initialization
FTM0->SC = FTM_SC_PWMEN1_MASK //Enable PWM channel 1output
|FTM_SC_PS(0); //TOIE(timer overflow Interrupt Ena) = 0 (deafault)
//CPWMS(Center aligned PWM Select) =0 (default, up count)
/* CLKS (Clock source) = 0 (default, no clock; FTM disabled) */
/* PS (Prescaler factor) = 0. Prescaler = 1 */
FTM0->MOD = 8000-1; //FTM0 counter final value (used for PWM mode)
// FTM0 Period = MOD-CNTIN+0x0001~=16000 ctr clks=8ms
//8Mhz /1 =8MHz -> ticks -> 1KHz
FTM0->CNTIN = FTM_CNTIN_INIT(0);
FTM0->CONTROLS[1].CnSC |=FTM_CnSC_MSB_MASK;
FTM0->CONTROLS[1].CnSC |=FTM_CnSC_ELSA_MASK; /* FTM0 ch1: edge-aligned PWM, low true pulses */
/* CHIE (Chan Interrupt Ena) = 0 (default) */
/* MSB:MSA (chan Mode Select)=0b10, Edge Align PWM */
/* ELSB:ELSA (chan Edge/Level Select)=0b10, low true */
}
void FTM0_CH1_PWM (){
FTM0->CONTROLS[1].CnV = 4000;//8000~0 duty; ex(7200=> Duty 0.1 / 800=>Duty 0.9)
//start FTM0 counter with clk source = external clock (SOSCDIV1_CLK)
FTM0->SC|=FTM_SC_CLKS(3);
}
void PORT_init (void)
{
/*!
* Pins definitions
* ===================================================
*
* Pin number | Function
* ----------------- |------------------
* PTD16 | FTM0CH1
*/
PCC->PCCn[PCC_PORTD_INDEX ]|=PCC_PCCn_CGC_MASK; /* Enable clock for PORTD */
PORTD->PCR[16]|=PORT_PCR_MUX(2); /* Port D16: MUX = ALT2, FTM0CH1 */
}
int main(void)
{
SOSC_init_8MHz(); /* Initialize system oscillator for 8 MHz xtal */
SPLL_init_160MHz(); /* Initialize SPLL to 160 MHz with 8 MHz SOSC */
NormalRUNmode_80MHz(); /* Init clocks: 80 MHz SPLL & core, 40 MHz bus, 20 MHz flash */
FTM_init();
FTM0_CH1_PWM ();
PORT_init(); /* Configure ports */
for(;;)
{
}
}
