树莓派结合ADC做个光敏感应的灯

内容纲要

树莓派结合ADC做个光敏感应灯

前言

其实没有什么想法,就是想把ADC用熟练了,这些小案例都是自己杜撰的,实际上没有那么多场景需要用,但是最近真的用在了智能浇花设备上,土壤湿度采样的传感器是模拟的,所以,可以用ADC秀一波操作。

操作步骤

  • 步骤1:从https://www.raspberrypi.org/downloads/下载最新镜像,然后选择Raspbian。
  • 步骤2:烧录镜像然后启动树莓派。 
  • 步骤3:通过在终端中键入以下命令连接到Internet并更新系统:
    sudo apt-get update
    sudo apt-get upgrade
  • 步骤4:将所有东西连接在一起然后打开你的树莓派,不知道为啥网上给树莓派起名字叫覆盆子,太tm难听了。raspberry就改成树莓不行么?

    手绘电路图,看懂了就过,看不懂就自己学习一下再过。

    接驳示意图,ADC的AIN1 通道采样。中间抽头给树莓派,采集信号信息。

    C语言编程

    下面的内容就是开始编程了,如果你喜欢用C,那么就这样,写个源码:

    #include <stdio.h>
    #include <stdlib.h>
    #include <linux/i2c-dev.h>
    #include <sys/ioctl.h>
    #include <fcntl.h>
    #include <wiringPi.h>
    void main()
    {
    wiringPiSetup(); 
    //Physical Pin = 40, name is GPIO.29 and wPi name is 29, BCM 21.
    pinMode(29, OUTPUT);   
    int file; 
    char *bus = "/dev/i2c-1";
    if ((file = open(bus, O_RDWR)) < 0) 
    {
     printf("Failed to open the bus.\n");
     exit(1);
     } 
    // Get I2C device, ADS1115 I2C address is 0x48(72)
    ioctl(file, I2C_SLAVE, 0x48) 
    // Select configuration register(0x01)
    // AINP = AIN0 and AINN = AIN1, +/- 2.048V 
    // Continuous conversion mode, 128 SPS(0x84, 0x83) 
    char config[3] = {0}; 
    config[0] = 0x01; 
    config[1] = 0xD4; 
    config[2] = 0x83; 
    write(file, config, 3); 
    sleep(1); 
    // Read 2 bytes of data from register(0x00) 
    // raw_adc msb, raw_adc lsb 
    char reg[1] = {0x00};
    write(file, reg, 1); 
    char data[2]={0};
    if(read(file, data, 2) != 2) 
    { 
    printf("Error : Input/Output Error\n");
    }
    else
    { 
    // Convert the data 
    int raw_adc = (data[0] * 256 + data[1]);
    if (raw_adc > 32767) 
    { 
      raw_adc -= 65535; 
    }
    // Output data to screen 
    printf("Analog Data is: %d \n", raw_adc);
    if ( raw_adc > 3200 )
     { 
      printf("Turn on LED\n");
      digitalWrite(29, LOW); // turn on the LED 
      } 
    else { 
        printf("Turn off LED\n"); 
        digitalWrite(29, HIGH);  //turn off the LED
          }
     } 
    }

    编译和测试:

    gcc -o adc -lwiringPi adc.c 

    注意:

  • gcc是编译工具,-o表示定义输出文件名,-lwiringPi表示需要使用wiringPi的库来完成编译代码。
  • 编译后,将在工作目录中获得名为sensor的二进制文件,只需使用此命令执行它:
    while true
    do
    ./adc 
    done

Python编程

  • 如果你喜欢用python好吧,那么就更简单了。直接用adafruit的ads1x15的代码改改就能用。
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # Author: Jacky.Li
    # License: Public Domain
    import time
    import Adafruit_ADS1x15
    import os
    adc = Adafruit_ADS1x15.ADS1115()
    # Choose a gain of 1 for reading voltages from 0 to 4.09V.
    # Or pick a different gain to change the range of voltages that are read:
    # - 2/3 = +/-6.144V
    # - 1 = +/-4.096V
    # - 2 = +/-2.048V
    # - 4 = +/-1.024V
    # - 8 = +/-0.512V
    # - 16 = +/-0.256V
    # See table 3 in the ADS1015/ADS1115 datasheet for more info on gain.
    GAIN = 1
    print("Reading ADS1115 values, press Ctrl-C to quit...") 
    # Main loop. 
    while True:
    # Read all the ADC channel values in a list.
    values = [0]*4
    for i in range(4):
    # Read the specified ADC channel using the previously set gain value.
    values[i] = adc.read_adc(i, gain=GAIN) 
    # Note you can also pass in an optional data_rate parameter that controls 
    # the ADC conversion time (in samples/second). Each chip has a different 
    # set of allowed data rate values, see datasheet Table 9 config register 
    # DR bit values. 
    #values[i] = adc.read_adc(i, gain=GAIN, data_rate=128) 
    # Each value will be a 12 or 16 bit signed integer value depending on the   
    # ADC (ADS1015 = 12-bit, ADS1115 = 16-bit). 
    # Print the ADC values. 
    print(values[1]) 
    # print analog data which detected via ADC AIN1 port.
    if values[1] < 3000: 
        os.system("gpio mode 29 out")
        os.system("gpio write 29 1") 
    else: 
        os.system("gpio mode 29 in") 
    os.system("gpio write 29 0") 
    time.sleep(0.25)</span>

    运行看看效果

    python sensor.py

    嗯,就这样吧,开开脑洞就可以玩儿得更愉快。。哈哈, 白了个白~

发布者

yoyojacky

我是骑驴玩儿漂移, 喜欢玩儿电子,喜欢的编程语言, C, shell, python, 爱玩儿的开发板: 树莓派, arduino,STM32系列, 还有3D 打印机,四轴飞行器,业余时间也喜欢玩儿吉他,非洲鼓. 欢迎来光临我的小站~

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