学习KEA之ADC之二：查询方式

拼搏现实的明天。 2023-02-21 02:29 2阅读 0赞

> 作者：曾Jerry 或 大橙员, 250359225@qq.com

[学习KEA之ADC之一：基本介绍][KEA_ADC]  
[学习KEA之ADC之二：查询方式][KEA_ADC 1]  
[学习KEA之ADC之三：中断方式][KEA_ADC 2]  
[学习KEA之ADC之四：FIFO][KEA_ADC_FIFO]

**需求：**

*  读取AD7(PTB3), AD12(PTF4), AD14(PTF6)，并转换成 mV, 范围是0 - 5000mV，这三个输入都是电压大概是2.157V, 2.146V, 2.144V。
 *  基本配置：时钟来自bus\_clock, 20MHz, Single模式， Software trigger，10-bit mode operation

**例程：**

#include "derivative.h" /* include peripheral declarations SSKEAZN64M2 */
    
    void Clk_Init(void);
    
    uint32_t adcResultInMv7 = 0;
    uint32_t adcResultInMv12 = 0;
    uint32_t adcResultInMv14 = 0;
    
    int main(void)
    { 
    	Clk_Init();
    	init_ADC();
    
    	adcResultInMv7 = ADC_Read(7);
    	adcResultInMv12 = ADC_Read(12);
    	adcResultInMv14 = ADC_Read(14);
    
    	for(;;)
    	{ 
    
    	}
    
    	return 0;
    }
    
    
    /*********************************************************************************************** * * @brief CLK_Init - Initialize Core Clock to 40MHz, Bus Clock to 20MHz * @param none * @return none * ************************************************************************************************/
    void Clk_Init(void)
    { 
    	ICS_C1|= ICS_C1_IRCLKEN_MASK; /* Enable the internal reference clock*/
    	ICS_C3 = 0x50; /* Reference clock frequency = 31.25 kHz*/
    
    	while(!(ICS_S & ICS_S_LOCK_MASK)); /* Wait for PLL lock, now running at 40 MHz (1024*39.0625 kHz) */
    
    	ICS_C2 |= ICS_C2_BDIV(1) ; /* BDIV=b001, Bus clock = 20 MHz*/
    	ICS_S |= ICS_S_LOCK_MASK ; /* Clear Loss of lock sticky bit */
    }
    
    void init_GPIO(void)
    { 
    	GPIOA_PDDR |= 1<<PTD2; /* Port D2: Data Direction= output */
    	GPIOA_PIDR &= 1<<PTD2; /* Port D2: Input Disable= 1 (default) */
    }
    
    void init_ADC(void)  { 
      SIM_SCGC |= SIM_SCGC_ADC_MASK; /* Enable bus clock in ADC*/
      ADC_SC3 |= ADC_SC3_ADICLK(0b00); /* Bus clock selected, 20 MHz*/
      ADC_SC2 |= 0x00; /* Software Conversion trigger, disable compare function*/
      ADC_SC2 |= ADC_SC2_REFSEL(0b01); /* Select VDD and VSS as voltage reference source*/
      ADC_SC1 = 0 ; /* Enable ADC by setting ADCH bits as low*/
      ADC_SC1 &= ~ADC_SC1_ADCO_MASK; /* Single mode operation */
      ADC_APCTL1 |= ADC_APCTL1_ADPC(1<<7 | 1<<12 | 1<<14); /* Channel selection */
      ADC_SC3 |= ADC_SC3_MODE(0b01); /* 10-bit mode operation */
    }
    
    uint32_t ADC_Read(char channel)
    { 
    	ADC_SC1 &= ~ADC_SC1_ADCH_MASK;         /* Clear any prior ADCH bits*/
    	ADC_SC1 |= ADC_SC1_ADCH(channel);      /* Select channel to read */
    	while(!(ADC_SC1 & ADC_SC1_COCO_MASK)); /* Wait conversion to complete */
    
    	//return ADC_R;
    	return (uint32_t) ((5000*ADC_R)/0x3FF);  /* Convert result to mv for 0-5V range */
    }

上面程序的仿真结果如下：  
![在这里插入图片描述][20200628112424546.png]  
如果启用12位的ADC采样，结果就更准确了：

void init_ADC(void)  { 
      SIM_SCGC |= SIM_SCGC_ADC_MASK; /* Enable bus clock in ADC*/
      ADC_SC3 |= ADC_SC3_ADICLK(0b00); /* Bus clock selected, 20 MHz*/
      ADC_SC2 |= 0x00; /* Software Conversion trigger, disable compare function*/
      ADC_SC2 |= ADC_SC2_REFSEL(0b01); /* Select VDD and VSS as voltage reference source*/
      ADC_SC1 = 0 ; /* Enable ADC by setting ADCH bits as low*/
      ADC_SC1 &= ~ADC_SC1_ADCO_MASK; /* Single mode operation */
      ADC_APCTL1 |= ADC_APCTL1_ADPC(1<<7 | 1<<12 | 1<<14); /* Channel selection */
      ADC_SC3 |= ADC_SC3_MODE(0b10); /* 12-bit mode operation */
    }
    
    uint32_t ADC_Read(char channel)
    { 
    	ADC_SC1 &= ~ADC_SC1_ADCH_MASK;         /* Clear any prior ADCH bits*/
    	ADC_SC1 |= ADC_SC1_ADCH(channel);      /* Select channel to read */
    	while(!(ADC_SC1 & ADC_SC1_COCO_MASK)); /* Wait conversion to complete */
    
    	//return ADC_R;
    	return (uint32_t) ((5000*ADC_R)/0xFFF);  /* Convert result to mv for 0-5V range */
    }

![在这里插入图片描述][20200628114130856.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW1lbmcxMTY_size_16_color_FFFFFF_t_70]

[KEA_ADC]: https://blog.csdn.net/feimeng116/article/details/106949471
[KEA_ADC 1]: https://blog.csdn.net/feimeng116/article/details/106998567
[KEA_ADC 2]: https://blog.csdn.net/feimeng116/article/details/107003190
[KEA_ADC_FIFO]: https://blog.csdn.net/feimeng116/article/details/107037460
[20200628112424546.png]: https://img-blog.csdnimg.cn/20200628112424546.png
[20200628114130856.png]: https://img-blog.csdnimg.cn/20200628114130856.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW1lbmcxMTY_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200702205236938.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW1lbmcxMTY=,size_16,color_FFFFFF,t_70