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[ESP8266/ESP32]利用Beetle ESP32-C3+ADS1115自制数字电压表

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2023-5-30 22:20:07 [显示全部楼层]
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[ESP8266/ESP32] 利用Beetle ESP32-C3+ADS1115自制数字电压表

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本帖最后由 glwz007 于 2023-5-30 22:20 编辑


    前言
感谢DFRobot提供活动的平台和提供硬件支持，祝DFRobot越办越好，人气越来越旺，祝各位创客老师们学习快乐，作品频出！
下面是活动链接：
一、项目由来

        我是一个物理老师，也是一个喜欢折腾实验的老师，在信息化数字化的浪潮下，一直有一个想法，就是将传统的物理实验信息化、数字化，在这方面我一直处于学习和不断的制作中。
        在中学物理实验中，电学实验也是一个重点，而电学实验，离不开电学三个基本物理量电压、电流、电阻的测量，这次先从电压的测量工具电压表入手进行学习。
        二、对电压表的对比分析
        1. 传统的电压表
        中学物理实验室传统的电压表都是电磁式电表，如下图所示：

      它是基于灵敏电流计G改装得到，下图是灵敏电流计G（俗称表头）的构造图，它的原理是利用通电线圈在磁场中受力转动，通过电流计的电流越大，与线圈相连接的指针转过的角度越大。

        通过串并联电路，可以将表头改装为不同量程的电压表和电流表。
这种传统的电流表，属于模拟式电压表，优点是结构简单，价格便宜，测量频率范围较宽；缺点是精度、分辨力较低，不便于与计算机组成自动测试系统。
        2.数字式电压表
        数字是电压表用A/D转换器和数字显示器代替了模拟电压表的测量显示部分，优缺点基本上正好与模拟式电压表相反。
        在中学实验室，常用的数字式电表，大多是商品化的DIS系统，DIS（ Digital Information System） 实验技术，又称“数字化信息系统”，是由“传感器、数据采集器、实验软件包（教材专用软件、通用扩展软件）、计算机”等构成的新型实验系统。该系统成功地克服了传统物理实验仪器的诸多弊端，有力地支持了信息技术与物理教学的全面整合。

        但是这种系统价格相对比较高，于是我萌生了自制数字电压表的想法，下面是初步的实验过程。
         三、基于Beetle ESP32-C3 + ADS1115的数字电压表
         前段时间，DFRobot论坛开展了Beetle ESP32-C3的免费试用活动，于是我申请了两块作为实验用主控板，在此向DFRobot表示衷心的感谢！
        （一）主要硬件
       本次使用的主要元件如下：
       1. 主控板：Beetle ESP32-C3，详细资料不再重复，可以看官网产品资料库信息。https://wiki.dfrobot.com.cn/_SKU_DFR0868_Beetle_ESP32_C3

       2.显示屏采用12864OLED，OLED 屏幕作为一种新型的显示技术，其自身可以发光，亮度，对比度高，功耗低，在当下备受追捧。而在我们正常的显示调整参数过程中，我们越来越多的使用这种屏幕。我们使用的一般是分辨率为 128x64 ，屏幕尺寸为 0.96 寸。

       3.AD转换器采用ADS1115，ADS1115是一种精密16位模数转换器（ADC），能将模拟信号转换为数字信号。它采用I2C接口进行通信，并具有四个单端或两个差分输入通道。由于其高精度和低功耗特性，ADS1115广泛用于温度、压力、湿度等传感器的数据采集与处理。

       （二）编程软件
       在以往的制作中，我大多数情况下采用图形化编程模式，这次转换使用代码编程。采用MicroPython，编辑器为Thonny。Thonny 是一个面向初学者的 Python IDE
Thonny 由爱沙尼亚的 Tartu 大学开发，它采用了不同的方法，因为它的调试器是专为学习和教学编程而设计的。

       （三）制作过程
       1. 硬件搭建
       将Beetle ESP32-C3、12864OLED屏、ADS1115通过连接线连接到面包板上，为了改变测量电压，还接了一个1KΩ的电位器，将电位器可变电压提供给自制电压表和数字万用表测量作为对比。连接示意图如下：

       2. 软件编程
       （1）首先要给Beetle ESP32-C3刷固件，刷固件的烧录工具、固件、方法采用官方资料中方法，参照如下链接：https://wiki.dfrobot.com.cn/_SKU_DFR0868_Beetle_ESP32_C3#target_24
       （2）编程环境配置
刷好固件后，启动Thonny，选择“运行”菜单，进行如下图配置：

       点击“视图”菜单中“文件”选项，如果前面配置正常，将会显示主控板中文件，一开始应该是空的。
       （3）新建”ssd1306.py”，复制下面代码，保存到“MicroPython设备”作为12864OLED显示屏的库。


  1. #MicroPython SSD1306 OLED driver, I2C and SPI interfaces created by Adafruit

  2.  

  3. import time

  4. import framebuf

  5.  

  6. # register definitions

  7. SET_CONTRAST        = const(0x81)

  8. SET_ENTIRE_ON       = const(0xa4)

  9. SET_NORM_INV        = const(0xa6)

  10. SET_DISP            = const(0xae)

  11. SET_MEM_ADDR        = const(0x20)

  12. SET_COL_ADDR        = const(0x21)

  13. SET_PAGE_ADDR       = const(0x22)

  14. SET_DISP_START_LINE = const(0x40)

  15. SET_SEG_REMAP       = const(0xa0)

  16. SET_MUX_RATIO       = const(0xa8)

  17. SET_COM_OUT_DIR     = const(0xc0)

  18. SET_DISP_OFFSET     = const(0xd3)

  19. SET_COM_PIN_CFG     = const(0xda)

  20. SET_DISP_CLK_DIV    = const(0xd5)

  21. SET_PRECHARGE       = const(0xd9)

  22. SET_VCOM_DESEL      = const(0xdb)

  23. SET_CHARGE_PUMP     = const(0x8d)

  24.  

  25.  

  26. class SSD1306:

  27.     def __init__(self, width, height, external_vcc):

  28.         self.width = width

  29.         self.height = height

  30.         self.external_vcc = external_vcc

  31.         self.pages = self.height // 8

  32.         # Note the subclass must initialize self.framebuf to a framebuffer.

  33.         # This is necessary because the underlying data buffer is different

  34.         # between I2C and SPI implementations (I2C needs an extra byte).

  35.         self.poweron()

  36.         self.init_display()

  37.  

  38.     def init_display(self):

  39.         for cmd in (

  40.             SET_DISP | 0x00, # off

  41.             # address setting

  42.             SET_MEM_ADDR, 0x00, # horizontal

  43.             # resolution and layout

  44.             SET_DISP_START_LINE | 0x00,

  45.             SET_SEG_REMAP | 0x01, # column addr 127 mapped to SEG0

  46.             SET_MUX_RATIO, self.height - 1,

  47.             SET_COM_OUT_DIR | 0x08, # scan from COM[N] to COM0

  48.             SET_DISP_OFFSET, 0x00,

  49.             SET_COM_PIN_CFG, 0x02 if self.height == 32 else 0x12,

  50.             # timing and driving scheme

  51.             SET_DISP_CLK_DIV, 0x80,

  52.             SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,

  53.             SET_VCOM_DESEL, 0x30, # 0.83*Vcc

  54.             # display

  55.             SET_CONTRAST, 0xff, # maximum

  56.             SET_ENTIRE_ON, # output follows RAM contents

  57.             SET_NORM_INV, # not inverted

  58.             # charge pump

  59.             SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,

  60.             SET_DISP | 0x01): # on

  61.             self.write_cmd(cmd)

  62.         self.fill(0)

  63.         self.show()

  64.  

  65.     def poweroff(self):

  66.         self.write_cmd(SET_DISP | 0x00)

  67.  

  68.     def contrast(self, contrast):

  69.         self.write_cmd(SET_CONTRAST)

  70.         self.write_cmd(contrast)

  71.  

  72.     def invert(self, invert):

  73.         self.write_cmd(SET_NORM_INV | (invert & 1))

  74.  

  75.     def show(self):

  76.         x0 = 0

  77.         x1 = self.width - 1

  78.         if self.width == 64:

  79.             # displays with width of 64 pixels are shifted by 32

  80.             x0 += 32

  81.             x1 += 32

  82.         self.write_cmd(SET_COL_ADDR)

  83.         self.write_cmd(x0)

  84.         self.write_cmd(x1)

  85.         self.write_cmd(SET_PAGE_ADDR)

  86.         self.write_cmd(0)

  87.         self.write_cmd(self.pages - 1)

  88.         self.write_framebuf()

  89.  

  90.     def fill(self, col):

  91.         self.framebuf.fill(col)

  92.  

  93.     def pixel(self, x, y, col):

  94.         self.framebuf.pixel(x, y, col)

  95.  

  96.     def scroll(self, dx, dy):

  97.         self.framebuf.scroll(dx, dy)

  98.  

  99.     def text(self, string, x, y, col=1):

  100.         self.framebuf.text(string, x, y, col)

  101.  

  102.  

  103. class SSD1306_I2C(SSD1306):

  104.     def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False):

  105.         self.i2c = i2c

  106.         self.addr = addr

  107.         self.temp = bytearray(2)

  108.         # Add an extra byte to the data buffer to hold an I2C data/command byte

  109.         # to use hardware-compatible I2C transactions.  A memoryview of the

  110.         # buffer is used to mask this byte from the framebuffer operations

  111.         # (without a major memory hit as memoryview doesn't copy to a separate

  112.         # buffer).

  113.         self.buffer = bytearray(((height // 8) * width) + 1)

  114.         self.buffer[0] = 0x40  # Set first byte of data buffer to Co=0, D/C=1

  115.         self.framebuf = framebuf.FrameBuffer1(memoryview(self.buffer)[1:], width, height)

  116.         super().__init__(width, height, external_vcc)

  117.  

  118.     def write_cmd(self, cmd):

  119.         self.temp[0] = 0x80 # Co=1, D/C#=0

  120.         self.temp[1] = cmd

  121.         self.i2c.writeto(self.addr, self.temp)

  122.  

  123.     def write_framebuf(self):

  124.         # Blast out the frame buffer using a single I2C transaction to support

  125.         # hardware I2C interfaces.

  126.         self.i2c.writeto(self.addr, self.buffer)

  127.  

  128.     def poweron(self):

  129.         pass

  130.  

  131.  

  132. class SSD1306_SPI(SSD1306):

  133.     def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):

  134.         self.rate = 10 * 1024 * 1024

  135.         dc.init(dc.OUT, value=0)

  136.         res.init(res.OUT, value=0)

  137.         cs.init(cs.OUT, value=1)

  138.         self.spi = spi

  139.         self.dc = dc

  140.         self.res = res

  141.         self.cs = cs

  142.         self.buffer = bytearray((height // 8) * width)

  143.         self.framebuf = framebuf.FrameBuffer1(self.buffer, width, height)

  144.         super().__init__(width, height, external_vcc)

  145.  

  146.     def write_cmd(self, cmd):

  147.         self.spi.init(baudrate=self.rate, polarity=0, phase=0)

  148.         self.cs.high()

  149.         self.dc.low()

  150.         self.cs.low()

  151.         self.spi.write(bytearray([cmd]))

  152.         self.cs.high()

  153.  

  154.     def write_framebuf(self):

  155.         self.spi.init(baudrate=self.rate, polarity=0, phase=0)

  156.         self.cs.high()

  157.         self.dc.high()

  158.         self.cs.low()

  159.         self.spi.write(self.buffer)

  160.         self.cs.high()

  161.  

  162.     def poweron(self):

  163.         self.res.high()

  164.         time.sleep_ms(1)

  165.         self.res.low()

  166.         time.sleep_ms(10)

  167.         self.res.high()
复制代码






       新建”ads1x15.py”，复制下面代码，保存到“MicroPython设备”作为ADS1115的库。


  1. # The MIT License (MIT)

  2. #

  3. # Copyright (c) 2016 Radomir Dopieralski (@deshipu),

  4. #               2017 Robert Hammelrath (@robert-hh)

  5. #

  6. # Permission is hereby granted, free of charge, to any person obtaining a copy

  7. # of this software and associated documentation files (the "Software"), to deal

  8. # in the Software without restriction, including without limitation the rights

  9. # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

  10. # copies of the Software, and to permit persons to whom the Software is

  11. # furnished to do so, subject to the following conditions:

  12. #

  13. # The above copyright notice and this permission notice shall be included in

  14. # all copies or substantial portions of the Software.

  15. #

  16. # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

  17. # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

  18. # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

  19. # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

  20. # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

  21. # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

  22. # THE SOFTWARE.

  23. #

  24. import utime as time

  25.  

  26. _REGISTER_MASK = const(0x03)

  27. _REGISTER_CONVERT = const(0x00)

  28. _REGISTER_CONFIG = const(0x01)

  29. _REGISTER_LOWTHRESH = const(0x02)

  30. _REGISTER_HITHRESH = const(0x03)

  31.  

  32. _OS_MASK = const(0x8000)

  33. _OS_SINGLE = const(0x8000)  # Write: Set to start a single-conversion

  34. _OS_BUSY = const(0x0000)  # Read: Bit=0 when conversion is in progress

  35. _OS_NOTBUSY = const(0x8000)  # Read: Bit=1 when no conversion is in progress

  36.  

  37. _MUX_MASK = const(0x7000)

  38. _MUX_DIFF_0_1 = const(0x0000)  # Differential P  =  AIN0, N  =  AIN1 (default)

  39. _MUX_DIFF_0_3 = const(0x1000)  # Differential P  =  AIN0, N  =  AIN3

  40. _MUX_DIFF_1_3 = const(0x2000)  # Differential P  =  AIN1, N  =  AIN3

  41. _MUX_DIFF_2_3 = const(0x3000)  # Differential P  =  AIN2, N  =  AIN3

  42. _MUX_SINGLE_0 = const(0x4000)  # Single-ended AIN0

  43. _MUX_SINGLE_1 = const(0x5000)  # Single-ended AIN1

  44. _MUX_SINGLE_2 = const(0x6000)  # Single-ended AIN2

  45. _MUX_SINGLE_3 = const(0x7000)  # Single-ended AIN3

  46.  

  47. _PGA_MASK = const(0x0E00)

  48. _PGA_6_144V = const(0x0000)  # +/-6.144V range  =  Gain 2/3

  49. _PGA_4_096V = const(0x0200)  # +/-4.096V range  =  Gain 1

  50. _PGA_2_048V = const(0x0400)  # +/-2.048V range  =  Gain 2 (default)

  51. _PGA_1_024V = const(0x0600)  # +/-1.024V range  =  Gain 4

  52. _PGA_0_512V = const(0x0800)  # +/-0.512V range  =  Gain 8

  53. _PGA_0_256V = const(0x0A00)  # +/-0.256V range  =  Gain 16

  54.  

  55. _MODE_MASK = const(0x0100)

  56. _MODE_CONTIN = const(0x0000)  # Continuous conversion mode

  57. _MODE_SINGLE = const(0x0100)  # Power-down single-shot mode (default)

  58.  

  59. _DR_MASK = const(0x00E0)     # Values ADS1015/ADS1115

  60. _DR_128SPS = const(0x0000)   # 128 /8 samples per second

  61. _DR_250SPS = const(0x0020)   # 250 /16 samples per second

  62. _DR_490SPS = const(0x0040)   # 490 /32 samples per second

  63. _DR_920SPS = const(0x0060)   # 920 /64 samples per second

  64. _DR_1600SPS = const(0x0080)  # 1600/128 samples per second (default)

  65. _DR_2400SPS = const(0x00A0)  # 2400/250 samples per second

  66. _DR_3300SPS = const(0x00C0)  # 3300/475 samples per second

  67. _DR_860SPS = const(0x00E0)  # -   /860 samples per Second

  68.  

  69. _CMODE_MASK = const(0x0010)

  70. _CMODE_TRAD = const(0x0000)  # Traditional comparator with hysteresis (default)

  71. _CMODE_WINDOW = const(0x0010)  # Window comparator

  72.  

  73. _CPOL_MASK = const(0x0008)

  74. _CPOL_ACTVLOW = const(0x0000)  # ALERT/RDY pin is low when active (default)

  75. _CPOL_ACTVHI = const(0x0008)  # ALERT/RDY pin is high when active

  76.  

  77. _CLAT_MASK = const(0x0004)  # Determines if ALERT/RDY pin latches once asserted

  78. _CLAT_NONLAT = const(0x0000)  # Non-latching comparator (default)

  79. _CLAT_LATCH = const(0x0004)  # Latching comparator

  80.  

  81. _CQUE_MASK = const(0x0003)

  82. _CQUE_1CONV = const(0x0000)  # Assert ALERT/RDY after one conversions

  83. _CQUE_2CONV = const(0x0001)  # Assert ALERT/RDY after two conversions

  84. _CQUE_4CONV = const(0x0002)  # Assert ALERT/RDY after four conversions

  85. # Disable the comparator and put ALERT/RDY in high state (default)

  86. _CQUE_NONE = const(0x0003)

  87.  

  88. _GAINS = (

  89.     _PGA_6_144V,  # 2/3x

  90.     _PGA_4_096V,  # 1x

  91.     _PGA_2_048V,  # 2x

  92.     _PGA_1_024V,  # 4x

  93.     _PGA_0_512V,  # 8x

  94.     _PGA_0_256V   # 16x

  95. )

  96.  

  97. _GAINS_V = (

  98.     6.144,  # 2/3x

  99.     4.096,  # 1x

  100.     2.048,  # 2x

  101.     1.024,  # 4x

  102.     0.512,  # 8x

  103.     0.256  # 16x

  104. )

  105.  

  106. _CHANNELS = {

  107.     (0, None): _MUX_SINGLE_0,

  108.     (1, None): _MUX_SINGLE_1,

  109.     (2, None): _MUX_SINGLE_2,

  110.     (3, None): _MUX_SINGLE_3,

  111.     (0, 1): _MUX_DIFF_0_1,

  112.     (0, 3): _MUX_DIFF_0_3,

  113.     (1, 3): _MUX_DIFF_1_3,

  114.     (2, 3): _MUX_DIFF_2_3,

  115. }

  116.  

  117. _RATES = (

  118.     _DR_128SPS,   # 128/8 samples per second

  119.     _DR_250SPS,   # 250/16 samples per second

  120.     _DR_490SPS,   # 490/32 samples per second

  121.     _DR_920SPS,   # 920/64 samples per second

  122.     _DR_1600SPS,  # 1600/128 samples per second (default)

  123.     _DR_2400SPS,  # 2400/250 samples per second

  124.     _DR_3300SPS,  # 3300/475 samples per second

  125.     _DR_860SPS    # - /860 samples per Second

  126. )

  127.  

  128.  

  129. class ADS1115:

  130.     def __init__(self, i2c, address=0x48, gain=1):

  131.         self.i2c = i2c

  132.         self.address = address

  133.         self.gain = gain

  134.         self.temp2 = bytearray(2)

  135.  

  136.     def _write_register(self, register, value):

  137.         self.temp2[0] = value >> 8

  138.         self.temp2[1] = value & 0xff

  139.         self.i2c.writeto_mem(self.address, register, self.temp2)

  140.  

  141.     def _read_register(self, register):

  142.         self.i2c.readfrom_mem_into(self.address, register, self.temp2)

  143.         return (self.temp2[0] << 8) | self.temp2[1]

  144.  

  145.     def raw_to_v(self, raw):

  146.         v_p_b = _GAINS_V[self.gain] / 32767

  147.         return raw * v_p_b

  148.  

  149.     def set_conv(self, rate=4, channel1=0, channel2=None):

  150.         """Set mode for read_rev"""

  151.         self.mode = (_CQUE_NONE | _CLAT_NONLAT |

  152.                      _CPOL_ACTVLOW | _CMODE_TRAD | _RATES[rate] |

  153.                      _MODE_SINGLE | _OS_SINGLE | _GAINS[self.gain] |

  154.                      _CHANNELS[(channel1, channel2)])

  155.  

  156.     def read(self, rate=4, channel1=0, channel2=None):

  157.         """Read voltage between a channel and GND.

  158.            Time depends on conversion rate."""

  159.         self._write_register(_REGISTER_CONFIG, (_CQUE_NONE | _CLAT_NONLAT |

  160.                              _CPOL_ACTVLOW | _CMODE_TRAD | _RATES[rate] |

  161.                              _MODE_SINGLE | _OS_SINGLE | _GAINS[self.gain] |

  162.                              _CHANNELS[(channel1, channel2)]))

  163.         while not self._read_register(_REGISTER_CONFIG) & _OS_NOTBUSY:

  164.             time.sleep_ms(1)

  165.         res = self._read_register(_REGISTER_CONVERT)

  166.         return res if res < 32768 else res - 65536

  167.  

  168.     def read_rev(self):

  169.         """Read voltage between a channel and GND. and then start

  170.            the next conversion."""

  171.         res = self._read_register(_REGISTER_CONVERT)

  172.         self._write_register(_REGISTER_CONFIG, self.mode)

  173.         return res if res < 32768 else res - 65536

  174.  

  175.     def alert_start(self, rate=4, channel1=0, channel2=None,

  176.                     threshold_high=0x4000, threshold_low=0, latched=False) :

  177.         """Start continuous measurement, set ALERT pin on threshold."""

  178.         self._write_register(_REGISTER_LOWTHRESH, threshold_low)

  179.         self._write_register(_REGISTER_HITHRESH, threshold_high)

  180.         self._write_register(_REGISTER_CONFIG, _CQUE_1CONV |

  181.                              _CLAT_LATCH if latched else _CLAT_NONLAT |

  182.                              _CPOL_ACTVLOW | _CMODE_TRAD | _RATES[rate] |

  183.                              _MODE_CONTIN | _GAINS[self.gain] |

  184.                              _CHANNELS[(channel1, channel2)])

  185.  

  186.     def conversion_start(self, rate=4, channel1=0, channel2=None):

  187.         """Start continuous measurement, trigger on ALERT/RDY pin."""

  188.         self._write_register(_REGISTER_LOWTHRESH, 0)

  189.         self._write_register(_REGISTER_HITHRESH, 0x8000)

  190.         self._write_register(_REGISTER_CONFIG, _CQUE_1CONV | _CLAT_NONLAT |

  191.                              _CPOL_ACTVLOW | _CMODE_TRAD | _RATES[rate] |

  192.                              _MODE_CONTIN | _GAINS[self.gain] |

  193.                              _CHANNELS[(channel1, channel2)])

  194.  

  195.     def alert_read(self):

  196.         """Get the last reading from the continuous measurement."""

  197.         res = self._read_register(_REGISTER_CONVERT)

  198.         return res if res < 32768 else res - 65536

  199.  

  200.  

  201. class ADS1113(ADS1115):

  202.     def __init__(self, i2c, address=0x48):

  203.         super().__init__(i2c, address, 1)

  204.  

  205.     def raw_to_v(self, raw):

  206.         return super().raw_to_v(raw)

  207.  

  208.     def read(self, rate=4):

  209.         return super().read(rate, 0, 1)

  210.  

  211.     def alert_start(self, rate=4, threshold_high=0x4000, threshold_low=0, latched=False):

  212.         return super().alert_start(rate, 0, 1, threshold_high, threshold_low, latched)

  213.  

  214.     def alert_read(self):

  215.         return super().alert_read()

  216.  

  217.  

  218. class ADS1114(ADS1115):

  219.     def __init__(self, i2c, address=0x48, gain=1):

  220.         super().__init__(i2c, address, gain)

  221.  

  222.     def raw_to_v(self, raw):

  223.         return super().raw_to_v(raw)

  224.  

  225.     def read(self, rate=4):

  226.         return super().read(rate, 0, 1)

  227.  

  228.     def alert_start(self, rate=4, threshold_high=0x4000, threshold_low=0, latched=False):

  229.         return super().alert_start(rate, 0, 1, threshold_high,

  230.             threshold_low, latched)

  231.  

  232.     def alert_read(self):

  233.         return super().alert_read()

  234.  

  235.  

  236. class ADS1015(ADS1115):

  237.     def __init__(self, i2c, address=0x48, gain=1):

  238.         super().__init__(i2c, address, gain)

  239.  

  240.     def raw_to_v(self, raw):

  241.         return super().raw_to_v(raw << 4)

  242.  

  243.     def read(self, rate=4, channel1=0, channel2=None):

  244.         return super().read(rate, channel1, channel2) >> 4

  245.  

  246.     def alert_start(self, rate=4, channel1=0, channel2=None, threshold_high=0x400,

  247.         threshold_low=0, latched=False):

  248.         return super().alert_start(rate, channel1, channel2, threshold_high << 4,

  249.             threshold_low << 4, latched)

  250.  

  251.     def alert_read(self):

  252.         return super().alert_read() >> 4
复制代码






       新建”main.py”，复制下面代码，作为主程序，主控板启动会自动执行这个程序。


  1. # 使用ADS1115测量电压，并用OLED屏幕显示

  2.  

  3. import ads1x15 ,time

  4. from machine import Pin, SoftI2C

  5. import ssd1306

  6. import time

  7.  

  8. i2c = SoftI2C(scl=Pin(9), sda=Pin(8),freq=400000)

  9. oled = ssd1306.SSD1306_I2C(128, 64 ,i2c)

  10. adc = ads1x15.ADS1115(i2c)

  11.  

  12. # 汉字字典

  13. character_dict = {

  14.     '电': [0x01,0x01,0x01,0x3F,0x21,0x21,0x21,0x3F,0x21,0x21,0x21,0x3F,0x21,0x01,0x01,0x00,

  15.         0x00,0x00,0x00,0xF8,0x08,0x08,0x08,0xF8,0x08,0x08,0x08,0xF8,0x0A,0x02,0x02,0xFE],

  16.     '压': [0x00,0x3F,0x20,0x20,0x20,0x20,0x20,0x2F,0x20,0x20,0x20,0x20,0x20,0x40,0x5F,0x80,

  17.         0x00,0xFE,0x00,0x80,0x80,0x80,0x80,0xFC,0x80,0x80,0x90,0x88,0x88,0x80,0xFE,0x00],

  18.     '流': [0x00,0x20,0x17,0x10,0x81,0x42,0x47,0x10,0x10,0x22,0xE2,0x22,0x22,0x22,0x24,0x08,

  19.         0x80,0x40,0xFE,0x80,0x10,0x08,0xFC,0x04,0x00,0x48,0x48,0x48,0x48,0x4A,0x4A,0x46],

  20.     '测': [0x00,0x27,0x14,0x14,0x85,0x45,0x45,0x15,0x15,0x25,0xE5,0x21,0x22,0x22,0x24,0x08,

  21.         0x04,0xC4,0x44,0x54,0x54,0x54,0x54,0x54,0x54,0x54,0x54,0x04,0x84,0x44,0x14,0x08],

  22.     '量': [0x00,0x1F,0x10,0x1F,0x10,0xFF,0x00,0x1F,0x11,0x1F,0x11,0x1F,0x01,0x1F,0x01,0x7F,

  23.         0x00,0xF0,0x10,0xF0,0x10,0xFE,0x00,0xF0,0x10,0xF0,0x10,0xF0,0x00,0xF0,0x00,0xFC],

  24.     'A': [0x00,0x00,0x00,0x10,0x10,0x18,0x28,0x28,0x24,0x3C,0x44,0x42,0x42,0xE7,0x00,0x00],

  25.     'V': [0x00,0x00,0x00,0xE7,0x42,0x42,0x44,0x24,0x24,0x28,0x28,0x18,0x10,0x10,0x00,0x00],

  26.     ':': [0x00,0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x00,0x00,0x00,0x00,0x18,0x18,0x00,0x00],

  27.     '-': [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00],

  28.     '.': [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x60,0x60,0x00,0x00],

  29.     '0': [0x00,0x00,0x00,0x18,0x24,0x42,0x42,0x42,0x42,0x42,0x42,0x42,0x24,0x18,0x00,0x00],

  30.     '1': [0x00,0x00,0x00,0x08,0x38,0x08,0x08,0x08,0x08,0x08,0x08,0x08,0x08,0x3E,0x00,0x00],

  31.     '2': [0x00,0x00,0x00,0x3C,0x42,0x42,0x42,0x02,0x04,0x08,0x10,0x20,0x42,0x7E,0x00,0x00],

  32.     '3': [0x00,0x00,0x00,0x3C,0x42,0x42,0x02,0x04,0x18,0x04,0x02,0x42,0x42,0x3C,0x00,0x00],

  33.     '4': [0x00,0x00,0x00,0x04,0x0C,0x0C,0x14,0x24,0x24,0x44,0x7F,0x04,0x04,0x1F,0x00,0x00],

  34.     '5': [0x00,0x00,0x00,0x7E,0x40,0x40,0x40,0x78,0x44,0x02,0x02,0x42,0x44,0x38,0x00,0x00],

  35.     '6': [0x00,0x00,0x00,0x18,0x24,0x40,0x40,0x5C,0x62,0x42,0x42,0x42,0x22,0x1C,0x00,0x00],

  36.     '7': [0x00,0x00,0x00,0x7E,0x42,0x04,0x04,0x08,0x08,0x10,0x10,0x10,0x10,0x10,0x00,0x00],

  37.     '8': [0x00,0x00,0x00,0x3C,0x42,0x42,0x42,0x24,0x18,0x24,0x42,0x42,0x42,0x3C,0x00,0x00],

  38.     '9': [0x00,0x00,0x00,0x38,0x44,0x42,0x42,0x42,0x46,0x3A,0x02,0x02,0x24,0x18,0x00,0x00]

  39. }

  40.  

  41.  

  42. # 显示中文

  43. def display_zh_character(character, x, y):

  44.     num_list = character_dict[character]

  45.     for i in range(16):

  46.         left = bin(num_list[i]).replace('0b', '')

  47.         right = bin(num_list[i + 16]).replace('0b', '')

  48.     

  49.         # 补 0

  50.         while len(left) < 8:

  51.             left = '0' + left

  52.         while len(right) < 8:

  53.             right = '0' + right

  54.         num_binary = left+right

  55.         for j in range(len(num_binary)):

  56.             oled.pixel(x + j, y + i, int(num_binary[j]))

  57.  

  58.  

  59. # 显示英文、数字和其他符号

  60. def display_en_character(character, x, y):

  61.     num_list = character_dict[character]

  62.     for i in range(16):

  63.         left = bin(num_list[i]).replace('0b', '')

  64.         # 补 0

  65.         while len(left) < 8:

  66.             left = '0' + left

  67.         num_binary = left

  68.         for j in range(len(num_binary)):

  69.             oled.pixel(x + j, y + i, int(num_binary[j]))

  70.  

  71.         

  72. def display_zh(text, x, y):

  73.     for i in range(len(text)):

  74.         display_zh_character(text[i], x + i * 16, y)

  75.  

  76. def display_en(text, x, y):

  77.     for i in range(len(text)):

  78.         display_en_character(text[i], x + i * 8, y)

  79.  

  80.  

  81. # 测量电压并显示在oled

  82. while True:

  83.     value = adc.read() 

  84.     voltage=str('{:.3f}'.format((value/2**15)*4.096)) #量程为4.096V

  85.     oled.fill(0)

  86.     display_zh('电压电流测量', 16, 3)

  87.     display_zh('电压', 0, 24)

  88.     display_en(":",32,24)

  89.     display_en(voltage,40,24)

  90.     display_en('V',(40+len(voltage)*8),24)

  91.     oled.show()

  92.     time.sleep(0.5)
复制代码






       完成后文件目录如下图所示：


  四、实验结果

       下图是连接成功，运行程序，进行测量电压的照片：

       下表是利用自制电压表和数字万用表测量结果对比，由表中可以看出，自制数字电压表测量结果和数字万用表测量结果基本一致，实验取得基本成功。

       近期学校事务较多，时间紧张，实验进行的比较简略和粗糙，我会在以后继续完善和扩充，请各位批评指正。实验中所用图片、库和部分代码，参考了网络资源，仅作为自己学习之用，如有侵权，请联系我修改删除。



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乘风破浪4700  学徒

发表于 2025-10-18 14:15:49

测自己的电压还是准的，但是测外电路就有误差了
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乘风破浪4700  学徒

发表于 2025-10-19 00:42:20

乘风破浪4700 发表于 2025-10-18 14:15
测自己的电压还是准的，但是测外电路就有误差了

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