S32K144 EVB之ADC

开发环境

IAR7.8 + S32K144-EVB

关于ADC的使用，参考了AN5413.pdf中的例程

首先是ADC初始化，使用PTC14和RGB灯相关引脚：

void ADC_init(void)
{
        PCC->PCCn[PCC_ADC0_INDEX] &=~ PCC_PCCn_CGC_MASK; /* Disable clock to change PCS */
        PCC->PCCn[PCC_ADC0_INDEX] |= PCC_PCCn_PCS(1); /* PCS=1: Select SOSCDIV2 */
        PCC->PCCn[PCC_ADC0_INDEX] |= PCC_PCCn_CGC_MASK; /* Enable bus clock in ADC */
        ADC0->SC1[0] = 0x0000003F;
        /* ADCH=3F: Module is disabled for conversions*/
        /* AIEN=0: Interrupts are disabled */
        ADC0->CFG1 = 0x000000004;
        /* ADICLK=0: Input clk=ALTCLK1=SOSCDIV2 */
        /* ADIV=0: Prescaler=1 */
        /* MODE=1: 12-bit conversion */
        ADC0->CFG2 = 0x00000000C;
        /* SMPLTS=12(default): sample time is 13 ADC clks */
        ADC0->SC2 = 0x00000000;
        /* ADTRG=0: SW trigger */
        /* ACFE,ACFGT,ACREN=0: Compare func disabled */
        /* DMAEN=0: DMA disabled */
        /* REFSEL=0: Voltage reference pins= VREFH, VREEFL */
        ADC0->SC3 = 0x00000000;
        /* CAL=0: Do not start calibration sequence */
        /* ADCO=0: One conversion performed */
        /* AVGE,AVGS=0: HW average function disabled */
}

然后是ADC相关函数:

void convertAdcChan(u16 adcChan)
{
        /* For SW trigger mode, SC1[0] is used */
        ADC0->SC1[0]&=~ADC_SC1_ADCH_MASK; /* Clear prior ADCH bits */
        ADC0->SC1[0] = ADC_SC1_ADCH(adcChan); /* Initiate Conversion*/
}

u8 adc_complete(void)
{
        return ((ADC0->SC1[0] & ADC_SC1_COCO_MASK)>>ADC_SC1_COCO_SHIFT); /* Wait for completion */
}

u32 read_adc_chx(void)
{
        u16 adc_result=0;
        adc_result = ADC0->R[0]; /* For SW trigger mode, R[0] is used */
        return (u32) ((5000*adc_result)/0xFFF); /* Convert result to mv for 0-5V range */
}

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;

#define RED     15
#define GREEN   16
#define BLUE    0

void SOSC_init_8MHz(void);
void SPLL_init_160MHz(void);
void NormalRUNmode_80MHz(void);

void PORT_init(void);
void LED_light(u8 color);
void ADC_init(void);
void convertAdcChan(u16 adcChan);
u8 adc_complete(void);
u32 read_adc_chx(void);

u8 color = 0;
u32 adcResultInMv = 0;

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 */
        PORT_init(); /* Init port clocks and gpio outputs */
        ADC_init(); /* Init ADC resolution 12 bit*/

        for(;;) {
                //PTC14
                convertAdcChan(12); /* Convert Channel AD12 to pot on EVB */
                while(adc_complete()==0){} /* Wait for conversion complete flag */
                adcResultInMv = read_adc_chx(); /* Get channel's conversion results in mv */

                color = adcResultInMv / 625;
                if (adcResultInMv == 5000)
                        color --;
                LED_light(color);

                //011101b - VREFSH is selected as input. Voltage reference selected is determined by SC2[REFSEL].
                convertAdcChan(29); /* Convert chan 29, Vrefsh */
                while(adc_complete()==0){} /* Wait for conversion complete flag */
                adcResultInMv = read_adc_chx(); /* Get channel's conversion results in mv */
        }
}

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[RED  ] = 0x00000100; /* Port D0: MUX = GPIO */
        PORTD->PCR[GREEN] = 0x00000100; /* Port D15: MUX = GPIO */
        PORTD->PCR[BLUE ] = 0x00000100; /* Port D16: MUX = GPIO */
        PTD->PDDR |= BIT(RED  ); /* Port D0: Data Direction= output */
        PTD->PDDR |= BIT(GREEN); /* Port D15: Data Direction= output */
        PTD->PDDR |= BIT(BLUE ); /* Port D16: Data Direction= output */
}

void LED_light(u8 color)
{
        PTD->PSOR |= BIT(RED) | BIT(GREEN) | BIT(BLUE);

        if (color & 0x01)
                PTD->PCOR |= BIT(RED);
        if (color & 0x02)
                PTD->PCOR |= BIT(GREEN);
        if (color & 0x04)
                PTD->PCOR |= BIT(BLUE);
}

void ADC_init(void)
{
        PCC->PCCn[PCC_ADC0_INDEX] &=~ PCC_PCCn_CGC_MASK; /* Disable clock to change PCS */
        PCC->PCCn[PCC_ADC0_INDEX] |= PCC_PCCn_PCS(1); /* PCS=1: Select SOSCDIV2 */
        PCC->PCCn[PCC_ADC0_INDEX] |= PCC_PCCn_CGC_MASK; /* Enable bus clock in ADC */
        ADC0->SC1[0] = 0x0000003F;
        /* ADCH=3F: Module is disabled for conversions*/
        /* AIEN=0: Interrupts are disabled */
        ADC0->CFG1 = 0x000000004;
        /* ADICLK=0: Input clk=ALTCLK1=SOSCDIV2 */
        /* ADIV=0: Prescaler=1 */
        /* MODE=1: 12-bit conversion */
        ADC0->CFG2 = 0x00000000C;
        /* SMPLTS=12(default): sample time is 13 ADC clks */
        ADC0->SC2 = 0x00000000;
        /* ADTRG=0: SW trigger */
        /* ACFE,ACFGT,ACREN=0: Compare func disabled */
        /* DMAEN=0: DMA disabled */
        /* REFSEL=0: Voltage reference pins= VREFH, VREEFL */
        ADC0->SC3 = 0x00000000;
        /* CAL=0: Do not start calibration sequence */
        /* ADCO=0: One conversion performed */
        /* AVGE,AVGS=0: HW average function disabled */
}

void convertAdcChan(u16 adcChan)
{
        /* For SW trigger mode, SC1[0] is used */
        ADC0->SC1[0]&=~ADC_SC1_ADCH_MASK; /* Clear prior ADCH bits */
        ADC0->SC1[0] = ADC_SC1_ADCH(adcChan); /* Initiate Conversion*/
}

u8 adc_complete(void)
{
        return ((ADC0->SC1[0] & ADC_SC1_COCO_MASK)>>ADC_SC1_COCO_SHIFT); /* Wait for completion */
}

u32 read_adc_chx(void)
{
        u16 adc_result=0;
        adc_result = ADC0->R[0]; /* For SW trigger mode, R[0] is used */
        return (u32) ((5000*adc_result)/0xFFF); /* Convert result to mv for 0-5V range */
}

编译运行，可以通过调节电位器来改变RGB灯的颜色。