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。