S32K144 EVB之FTM

开发环境

IAR7.8 + S32K144-EVB

关于FTM的使用，参考了AN5413.pdf中的例程

首先是端口初始化，使用PTD15和PTD16引脚：

void PORT_init(void)
{
        PCC->PCCn[PCC_PORTD_INDEX ]|=PCC_PCCn_CGC_MASK; /* Enable clock for PORTD */
        PORTD->PCR[15]|=PORT_PCR_MUX(2); /* Port D15: MUX = ALT2, FTM0CH0 red */
        PORTD->PCR[16]|=PORT_PCR_MUX(2); /* Port D16: MUX = ALT2, FTM0CH1 green */
}

然后是FTM模块初始化:

void FTM0_init(void)
{
        PCC->PCCn[PCC_FTM0_INDEX] &= ~PCC_PCCn_CGC_MASK; /* Ensure clk disabled for config */
        PCC->PCCn[PCC_FTM0_INDEX] |= PCC_PCCn_PCS(1) | PCC_PCCn_CGC_MASK;
        /* Clock Src=1, 8 MHz SOSCDIV1_CLK */
        /* Enable clock for FTM regs */
        FTM0->MODE |= FTM_MODE_WPDIS_MASK; /* Write protect to registers disabled (default) */
        FTM0->SC |= FTM_SC_PWMEN1_MASK | FTM_SC_PWMEN0_MASK | FTM_SC_PS(7);
        /* Enable PWM channel 0,1 output*/
        /* TOIE (Timer Overflow Interrupt Ena) = 0 (default) */
        /* CPWMS (Center aligned PWM Select) = 0 (default, up count) */
        /* CLKS (Clock source) = 0 (default, no clock; FTM disabled) */
        /* PS (Prescaler factor) = 7. Prescaler = 128 */
        FTM0->COMBINE = 0x00000000;/* FTM mode settings used: DECAPENx, MCOMBINEx, COMBINEx=0 */
        FTM0->POL = 0x00000000; /* Polarity for all channels is active high (default) */
        FTM0->MOD = 62500 -1 ; /* FTM1 counter final value (used for PWM mode) */
        /* FTM1 Period = MOD-CNTIN+0x0001 ~= 62500 ctr clks */
        /* 8MHz / 128 = 62500Hz -> ticks -> 1Hz */
        FTM0->SC |= FTM_SC_CPWMS_MASK;
}

void FTM0_CH0_init(void)
{
        FTM0->CONTROLS[0].CnSC = 0x00000008;

        FTM0->CONTROLS[0].CnV = 31250;
}

void FTM0_CH1_init(void)
{
        FTM0->CONTROLS[1].CnSC = 0x00000008;

        FTM0->CONTROLS[1].CnV = 31250;
}

void start_FTM0_counter(void)
{
        FTM0->SC |= FTM_SC_CLKS(3);
        /* Start FTM0 counter with clk source = external clock (SOSCDIV1_CLK)*/
}

注意，在CPWM模式时，CnV的值不能超过0x7FFF:

全部示例代码如下：

#include "S32K144.h"
#include "S32K144_features.h"
#include "fsl_core_cm4.h"

#define BIT(n)          (1 << (n))
#define UNUSED(x)       ((void)(x))
#define do_nothing()    {static u32 cnt = 0;cnt ++;}
#define ARRAY_SIZE(x)   (sizeof(x)/sizeof(x[0]))

typedef unsigned char   u8;
typedef unsigned short  u16;
typedef unsigned long   u32;

void SOSC_init_8MHz(void);
void SPLL_init_160MHz(void);
void NormalRUNmode_80MHz(void);
void PORT_init(void);
void FTM0_init(void);
void FTM0_CH0_init(void);
void FTM0_CH1_init(void);
void start_FTM0_counter(void);

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 */
        FTM0_init(); /* Init FTM0 */
        FTM0_CH0_init(); /* Init FTM0 CH0 */
        FTM0_CH1_init(); /* Init FTM0 CH1 */
        PORT_init(); /* Configure ports */
        start_FTM0_counter(); /* Start FTM0 counter */
        for(;;) {
                do_nothing();
        }
}

void SOSC_init_8MHz(void)
{
        SCG->SOSCDIV=0x00000101; /* SOSCDIV1 & SOSCDIV2 =1: divide by 1 */
        SCG->SOSCCFG=0x00000024; /* Range=2: Medium freq (SOSC between 1MHz-8MHz)*/
        /* HGO=0: Config xtal osc for low power */
        /* EREFS=1: Input is external XTAL */
        while(SCG->SOSCCSR & SCG_SOSCCSR_LK_MASK); /* Ensure SOSCCSR unlocked */
        SCG->SOSCCSR=0x00000001; /* LK=0: SOSCCSR can be written */
        /* SOSCCMRE=0: OSC CLK monitor IRQ if enabled */
        /* SOSCCM=0: OSC CLK monitor disabled */
        /* SOSCERCLKEN=0: Sys OSC 3V ERCLK output clk disabled */
        /* SOSCLPEN=0: Sys OSC disabled in VLP modes */
        /* SOSCSTEN=0: Sys OSC disabled in Stop modes */
        /* SOSCEN=1: Enable oscillator */
        while(!(SCG->SOSCCSR & SCG_SOSCCSR_SOSCVLD_MASK)); /* Wait for sys OSC clk valid */
}

void SPLL_init_160MHz(void)
{
        while(SCG->SPLLCSR & SCG_SPLLCSR_LK_MASK); /* Ensure SPLLCSR unlocked */
        SCG->SPLLCSR = 0x00000000; /* SPLLEN=0: SPLL is disabled (default) */
        SCG->SPLLDIV = 0x00000302; /* SPLLDIV1 divide by 2; SPLLDIV2 divide by 4 */
        SCG->SPLLCFG = 0x00180000; /* PREDIV=0: Divide SOSC_CLK by 0+1=1 */
        /* MULT=24: Multiply sys pll by 4+24=40 */
        /* SPLL_CLK = 8MHz / 1 * 40 / 2 = 160 MHz */
        while(SCG->SPLLCSR & SCG_SPLLCSR_LK_MASK); /* Ensure SPLLCSR unlocked */
        SCG->SPLLCSR = 0x00000001; /* LK=0: SPLLCSR can be written */
        /* SPLLCMRE=0: SPLL CLK monitor IRQ if enabled */
        /* SPLLCM=0: SPLL CLK monitor disabled */
        /* SPLLSTEN=0: SPLL disabled in Stop modes */
        /* SPLLEN=1: Enable SPLL */
        while(!(SCG->SPLLCSR & SCG_SPLLCSR_SPLLVLD_MASK)); /* Wait for SPLL valid */
}

void NormalRUNmode_80MHz(void)
{
        /* Change to normal RUN mode with 8MHz SOSC, 80 MHz PLL*/
        SCG->RCCR=SCG_RCCR_SCS(6) | SCG_RCCR_DIVCORE(1) | SCG_RCCR_DIVBUS(1) | SCG_RCCR_DIVSLOW(2);
        /* PLL as clock source*/
        /* DIVCORE=1, div. by 2: Core clock = 160/2 MHz = 80 MHz*/
        /* DIVBUS=1, div. by 2: bus clock = 40 MHz*/
        /* DIVSLOW=2, div. by 3: SCG slow, flash clock= 26 2/3 MHz*/
        while (((SCG->CSR & SCG_CSR_SCS_MASK) >> SCG_CSR_SCS_SHIFT ) != 6) {}
        /* Wait for sys clk src = SPLL */
}

void PORT_init(void)
{
        PCC->PCCn[PCC_PORTD_INDEX ]|=PCC_PCCn_CGC_MASK; /* Enable clock for PORTD */
        PORTD->PCR[15]|=PORT_PCR_MUX(2); /* Port D15: MUX = ALT2, FTM0CH0 red */
        PORTD->PCR[16]|=PORT_PCR_MUX(2); /* Port D16: MUX = ALT2, FTM0CH1 green */
}

void FTM0_init(void)
{
        PCC->PCCn[PCC_FTM0_INDEX] &= ~PCC_PCCn_CGC_MASK; /* Ensure clk disabled for config */
        PCC->PCCn[PCC_FTM0_INDEX] |= PCC_PCCn_PCS(1) | PCC_PCCn_CGC_MASK;
        /* Clock Src=1, 8 MHz SOSCDIV1_CLK */
        /* Enable clock for FTM regs */
        FTM0->MODE |= FTM_MODE_WPDIS_MASK; /* Write protect to registers disabled (default) */
        FTM0->SC |= FTM_SC_PWMEN1_MASK | FTM_SC_PWMEN0_MASK | FTM_SC_PS(7);
        /* Enable PWM channel 0 output*/
        /* TOIE (Timer Overflow Interrupt Ena) = 0 (default) */
        /* CPWMS (Center aligned PWM Select) = 0 (default, up count) */
        /* CLKS (Clock source) = 0 (default, no clock; FTM disabled) */
        /* PS (Prescaler factor) = 7. Prescaler = 128 */
        FTM0->COMBINE = 0x00000000;/* FTM mode settings used: DECAPENx, MCOMBINEx, COMBINEx=0 */
        FTM0->POL = 0x00000000; /* Polarity for all channels is active high (default) */
        FTM0->MOD = 62500 -1 ; /* FTM1 counter final value (used for PWM mode) */
        /* FTM1 Period = MOD-CNTIN+0x0001 ~= 62500 ctr clks */
        /* 8MHz / 128 = 62500Hz -> ticks -> 1Hz */
        FTM0->SC |= FTM_SC_CPWMS_MASK;
}

void FTM0_CH0_init(void)
{
        //mode select
        FTM0->CONTROLS[0].CnSC = 0x00000008;
        /* FTM0 ch0 compare value (~50% duty cycle) */
        FTM0->CONTROLS[0].CnV = 31250;
}

void FTM0_CH1_init(void)
{
        //mode select
        FTM0->CONTROLS[1].CnSC = 0x00000008;
        /* FTM0 ch1 compare value (~50% duty cycle) */
        FTM0->CONTROLS[1].CnV = 31250;
}

void start_FTM0_counter(void)
{
        FTM0->SC |= FTM_SC_CLKS(3);
        /* Start FTM0 counter with clk source = external clock (SOSCDIV1_CLK)*/
}

编译运行，即可见LED灯以1s的周期闪烁黄色灯光