用于树莓派的数据采集卡MCC简介及代码

树莓派（Raspberry)官网https://www.raspberrypi.org/

树莓派在某些小规模的数据采集和显示方面具有笔记本等大型设备所不具有的小巧灵活特性，入门树莓派同时相当于入门linux系统的小型计算机，树莓派的学习应用为后面的嵌入式开发也提供有必要的基础和储备，树莓派用于工业的flagship应用当属数据采集，本文主要介绍使用MCC配合树莓派进行数据的采集，同时使用在树莓派的Python程序来进行数据采集和显示。

MCC介绍

主要的MCC说明信息链接：https://mccdaq.github.io/daqhats/overview.html#functional-block-diagram

MCC的数据采集介绍：https://shumeipai.nxez.com/2018/12/28/raspberry-pi-and-mcc118-for-data-collection.html

树莓派上的Python程序实现数据采集

其相应的参考代码可以通过github 查询MCC工程，里面有详细的不同情况代码，其中实时采集的参考代码如下：

方便用于实时采集的MCC数据采集，显示：

#!/usr/bin/env python3
"""
    MCC 118 Control Panel

    Purpose:
        Display the MCC 118 input voltages

    Description:
        This app reads and displays the input voltages.
"""
from daqhats import hat_list, mcc118, HatIDs, HatError
from tkinter import *
from tkinter import messagebox
import tkinter.font
# matplotlib command
import matplotlib

import matplotlib.pyplot as plt

import numpy as np
# matplotlib command

class ControlApp:

    def __init__(self, master):
        self.master = master
        master.title("MCC 118 Control Panel")

        # Initialize variables
        self.device_open = False
        self.open_address = 0
        self.board = None

        # GUI Setup

        self.BOLD_FONT = tkinter.font.Font(
            family=tkinter.font.nametofont("TkDefaultFont")["family"],
            size=tkinter.font.nametofont("TkDefaultFont")["size"],
            weight="bold")

        # Create and organize frames
        self.top_frame = LabelFrame(master, text="Select Device")
        self.top_frame.pack(side=TOP, expand=False, fill=X)

        self.bottom_frame = LabelFrame(master, text="Analog Inputs")
        self.bottom_frame.pack(side=BOTTOM, expand=True, fill=BOTH)

        # Create widgets

        self.dev_label = Label(self.top_frame, text="MCC 118 address:")
        self.dev_label.grid(row=0, column=0)

        self.open_button = Button(self.top_frame, text="Open", width=6, command=self.pressedOpenButton)

        # Get list of MCC 118 devices for the device list widget
        self.addr_list = self.listDevices()

        if len(self.addr_list) == 0:
            self.device_lister = Label(self.top_frame, text="None found")
            self.open_button.config(state=DISABLED)
        else:
            self.device_variable = StringVar(self.top_frame)
            self.device_variable.set(self.addr_list[0])
            self.device_lister = OptionMenu(self.top_frame, self.device_variable, *self.addr_list)

        self.device_lister.grid(row=0, column=1)
        self.open_button.grid(row=0, column=2)

        self.checkboxes = []
        self.check_values = []
        self.channel_labels = []
        self.voltages = []
        for index in range(mcc118.info().NUM_AI_CHANNELS):
            # Checkboxes
            self.check_values.append(IntVar())
            self.checkboxes.append(Checkbutton(self.bottom_frame, variable=self.check_values[index], command=lambda index=index:self.pressedCheck(index)))
            self.checkboxes[index].grid(row=index, column=0)
            self.checkboxes[index].select()
            # Labels
            self.channel_labels.append(Label(self.bottom_frame, text="Ch {}".format(index), font=self.BOLD_FONT))
            self.channel_labels[index].grid(row=index, column=1)
            self.channel_labels[index].grid_configure(sticky="W")
            # Voltages
            self.voltages.append(Label(self.bottom_frame, text="0.000", font=self.BOLD_FONT))
            self.voltages[index].grid(row=index, column=2)
            self.voltages[index].grid_configure(sticky="E")

            self.bottom_frame.grid_rowconfigure(index, weight=1)

        self.bottom_frame.grid_columnconfigure(1, weight=1)
        self.bottom_frame.grid_columnconfigure(2, weight=1)

        self.bottom_frame.bind("", self.resizeText)

        # Disable widgets until a device is opened
        self.disableControls()

        master.protocol('WM_DELETE_WINDOW', self.close) # exit cleanup

        icon = PhotoImage(file='/usr/share/mcc/daqhats/icon.png')
        master.tk.call('wm', 'iconphoto', master._w, icon)

    def resizeText(self, event):
        new_size = -max(12, int(event.height / 12))
        self.BOLD_FONT.configure(size=new_size)

    def pressedCheck(self, index):
        if self.check_values[index].get() == 0:
            self.channel_labels[index].config(state=DISABLED)
            self.voltages[index].config(state=DISABLED)
        else:
            self.channel_labels[index].config(state=NORMAL)
            self.voltages[index].config(state=NORMAL)

    def disableControls(self):
        # Enable the address selector
        self.device_lister.config(state=NORMAL)
        # Disable the board controls
        for child in self.bottom_frame.winfo_children():
            child.config(state=DISABLED)

    def enableControls(self):
        # Disable the address selector
        self.device_lister.config(state=DISABLED)
        # Enable the board controls
        for child in self.bottom_frame.winfo_children():
            child.config(state=NORMAL)

    def listDevices(self):
        self.dev_list = hat_list(HatIDs.MCC_118)
        addr_list = ["{}".format(dev.address) for dev in self.dev_list]
        return addr_list

    def openDevice(self, address):
        try:
            self.board = mcc118(address)
        except:
            return False
        else:
            return True

    def closeDevice(self):
        self.board = None

    def updateInputs(self):
        if self.device_open:
            for channel in range(mcc118.info().NUM_AI_CHANNELS):
                if self.check_values[channel].get() == 1:
                    value = self.board.a_in_read(channel)
                    self.voltages[channel].config(text="{:.3f}".format(value))
                    # corresponing with the channel 1
                    #t = np.arange(1, 10000, 1)
                    s=self.board.a_in_read(1)
                    fig, ax = plt.subplots()

ax.plot( s)




            # schedule another update in 200 ms
            self.master.after(200, self.updateInputs)

    # Event handlers
    def pressedOpenButton(self):
        if self.open_button.cget('text') == "Open":
            # Open the selected device
            address = int(self.device_variable.get())
            if self.openDevice(address):
                self.device_open = True
                self.open_address = address

                self.enableControls()

                # Periodically read the inputs and update controls
                self.updateInputs()

                self.open_button.config(text="Close")
            else:
                messagebox.showerror("Error", "Could not open device.")
        else:
            if self.device_open:
                self.closeDevice()
                self.device_open = False
            self.open_button.config(text="Open")
            self.disableControls()

    def close(self):
        self.master.destroy()


root = Tk()
app = ControlApp(root)
root.mainloop()

该文主要用于MCC的数据采集入门，通过树莓派结合MCC，Python 实现数据的采集，处理，显示等基础功能