PSoc™62开发板之ADC读取电压

实验目的

1.使用ADC1读取可调电位器电压值

2.使用OLED显示电压值

实验准备

PSoc62™开发板
电位器
SSD1306 OLED模块
公母头杜邦线

组件配置

ADC配置

RT-Thread的HAL层目前只适配了ADC1，在RT-Thread Settings里边只能看到一个选项，我们把它开启了

ADC1设备使能.png

打开libraries/HAL_Drivers/drv_adc.c文件，发现ADC1对应的GPIO为P10.0

adc文件.png

OLED配置

OLED模块的主控是ssd1306，需要在RT-Thread Settings里边使能u8g2软件包，这里使用软件的方式模拟i2c时序

使能u8g2软件包.png

注意要在代码里边绑定i2c引脚，pin number和GPIO的对应关系：P8.0 : 8 x 8 = 64，P8.1 : 8 x 8 + 1 = 65

#define OLED_I2C_PIN_SCL                    64  // P8.0
#define OLED_I2C_PIN_SDA                    65  // P8.1

模块电路

OLED

MCU_ARD_SCL -> P8.0

oled连接图00.jpg

MCU_ARD_SDA -> P8.1

i2c引脚图.png

右侧排母从上往下第1、2引脚分别对应SCL、SDA

i2c模块图.png

依次连接OLED模块的VCC、GND、SDL、SDA引脚

oled连接图00.jpg

电位器

下图中的①、②、③引脚分别连接电位器的VCC、GND、OUT引脚，③即A0代表P10.0

电位器引脚.png

电位器连接图.jpg

程序设计

由于RT-Thread给PSoc62™适配的ADC驱动有一些问题，这里需要修改一下电压获取接口，打开libraries/HAL_Drivers/drv_adc.c文件，修改函数ifx_get_adc_value的实现：用cyhal_adc_read_uv接口替代cyhal_adc_read

#define MICRO_TO_MILLI_CONV_RATIO        (1000u)
static rt_err_t ifx_get_adc_value(struct rt_adc_device *device, rt_uint32_t channel, rt_uint32_t *value)
 {
  cyhal_adc_channel_t *adc_ch;
 
  RT_ASSERT(device != RT_NULL);
  adc_ch = device->parent.user_data;
 
  channel = adc_ch->channel_idx;
 
 #if 1
  *value = cyhal_adc_read_uv(adc_ch) / MICRO_TO_MILLI_CONV_RATIO;
 #else
  *value = cyhal_adc_read(adc_ch);
 #endif
  return RT_EOK;
 }

OLED初始化

// OLED
 u8g2_t u8g2;
 char buffer[50];
 u8g2_Setup_ssd1306_i2c_128x64_noname_f( &u8g2, U8G2_R0, u8x8_byte_sw_i2c, u8x8_gpio_and_delay_rtthread);
 u8x8_SetPin(u8g2_GetU8x8(&u8g2), U8X8_PIN_I2C_CLOCK, OLED_I2C_PIN_SCL);
 u8x8_SetPin(u8g2_GetU8x8(&u8g2), U8X8_PIN_I2C_DATA, OLED_I2C_PIN_SDA);
 u8g2_InitDisplay(&u8g2);
 u8g2_SetPowerSave(&u8g2, 0);

ADC1初始化

// ADC1
 rt_adc_device_t adc_dev;
 rt_uint32_t value;
 rt_err_t ret = RT_EOK;
 
 adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);
 if (adc_dev == RT_NULL)
 {
 rt_kprintf("adc sample run failed! can't find %s device!\n", ADC_DEV_NAME);
 }
 
 ret = rt_adc_enable(adc_dev, ADC_DEV_CHANNEL);
 if(ret == RT_EOK)
 {
 rt_kprintf("adc sample run success!  find %s device!\n", ADC_DEV_NAME);
 }

整合代码

#include <rtthread.h>
 #include <rtdbg.h>
 #include <board.h>
 #include <rtdevice.h>
 #include <u8g2_port.h>
 
 #define OLED_I2C_PIN_SCL                    64  // P8.0
 #define OLED_I2C_PIN_SDA                    65  // P8.1
 
 #define ADC_DEV_NAME        "adc1" 
 #define ADC_DEV_CHANNEL     0 
 
 int main(void)
 {
  // OLED
  u8g2_t u8g2;
  char buffer[50];
  u8g2_Setup_ssd1306_i2c_128x64_noname_f( &u8g2, U8G2_R0, u8x8_byte_sw_i2c, u8x8_gpio_and_delay_rtthread);
  u8x8_SetPin(u8g2_GetU8x8(&u8g2), U8X8_PIN_I2C_CLOCK, OLED_I2C_PIN_SCL);
  u8x8_SetPin(u8g2_GetU8x8(&u8g2), U8X8_PIN_I2C_DATA, OLED_I2C_PIN_SDA);
  u8g2_InitDisplay(&u8g2);
  u8g2_SetPowerSave(&u8g2, 0);
 
  // ADC1
  rt_adc_device_t adc_dev;
  rt_uint32_t value;
  rt_err_t ret = RT_EOK;
 
  adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);
  if (adc_dev == RT_NULL)
  {
  rt_kprintf("adc sample run failed! can't find %s device!\n", ADC_DEV_NAME);
  }
  /* 使能设备 */
  ret = rt_adc_enable(adc_dev, ADC_DEV_CHANNEL);
  if(ret == RT_EOK)
  {
  rt_kprintf("adc sample run success!  find %s device!\n", ADC_DEV_NAME);
  }
 
  while(1)
  {
  // read adc value
  value = rt_adc_read(adc_dev, ADC_DEV_CHANNEL);
  memset(buffer, 0, 50);
 
  if(4294965 <= value) value = 0;
  snprintf(buffer, 50, "Voltage : %d.%02dV\n", value / 1000, value % 1000);
 
  // display on OLED
  u8g2_ClearBuffer(&u8g2);
  u8g2_SetFont(&u8g2, u8g2_font_ncenB08_tr);
 
  u8g2_DrawStr(&u8g2, 20, 36, buffer);
  u8g2_SendBuffer(&u8g2);
  cyhal_system_delay_ms(200);
  }
  return 0;
 }

实验效果

使用示波器查看电位器不同旋转位置时的输出电压值，和OLED显示的ADC1电压值做比较，3.3V和1.1V的数值基本吻合

3.3V测量结果

电压3.3.jpg

1.1V测量结果

电压1.1.jpg