【Python实战系列】串口实时接收数据并基于pyqtgraph绘图

╰半夏微凉° 2022-08-29 11:57 355阅读 0赞

# 0、前言 #

串口数据图形化调试助手，这乍一听起来貌似还挺阔以的样子。那究竟是啥子呢？且听慢慢道来。事情的缘由是当前在做的一个项目中，在调试Mag(地磁)相关的Sensor。获取Mag的原始数据之后，首先要做的就是判断原始数据的质量如何，及是否是我们想要的数据，不仅要看数据是否在相应状况下处于合理的范围内，且数据的变化是否符合规律，所以呢需要一个能将原始数据实时绘制成图的工具。OK，那么来列举一下需求：

1.  串口通讯：串口打印是嵌入式开发时重要的调试手段，所以此处数据也通过串口传输给上位机；
2.  实时图表：将串口输出的数据实时绘图；
3.  至少能够同时绘制更新三组数据(x轴、y轴、z轴)数据。

# 1、相关库的安装 #

pip install pyserial  	#python 串口库
    pip install pyqtgraph	#安装pyqtgraph	
    pip install PyQt5		#安装python QT

![在这里插入图片描述][fd0df81721d34841b4c576edb902ee3a.jpg_x-oss-process_pic_center]

# 2、实战实例 #

#!/usr/bin/env python
    #-*-coding:utf-8 -*-
    import os
    import sys
    import time
    import signal
    import string
    import pyqtgraph as pg
    import array
    import serial
    import threading
    import numpy as np
    from queue import Queue
    import re
    
    i = 0
    q_mag_x = Queue(maxsize=0)
    q_mag_y = Queue(maxsize=0)
    q_mag_z = Queue(maxsize=0)
    curve_num = 0;
    
    def Serial():
        global i;
        global q_mag_x;
        global q_mag_y;
        global q_mag_z;
        ret = b''
        while(True):
            n = mSerial.inWaiting()
            if(n):
                ret = mSerial.readline()
                print(ret)
                if len(ret):
                    data_get = ret.decode('UTF-8')
                    pattern = re.compile(r"[+-]?\d+(?:\.\d+)?")   # find the num
                    data_all = pattern.findall(data_get)
                    print(data_all)
                    for j in range(len(data_all)):
                        if j==0:
                            q_mag_x.put(data_all[j])
                        if j==1:
                            q_mag_y.put(data_all[j])
                        if j==2:
                            q_mag_z.put(data_all[j])
    
    def plotData():
        global i;
        if i < historyLength:
            data_x[i] = q_mag_x.get()
            if curve_num >= 2:
                data_y[i] = q_mag_y.get()
            if curve_num >= 3:
                data_z[i] = q_mag_z.get()
            i = i+1
        else:
            data_x[:-1] = data_x[1:]
            data_x[i-1] = q_mag_x.get()
            if curve_num >= 2:
                data_y[:-1] = data_y[1:]
                data_y[i-1] = q_mag_y.get()
            if curve_num >= 3:
                data_z[:-1] = data_z[1:]
                data_z[i-1] = q_mag_z.get()
    
        curve1.setData(data_x)
        curve2.setData(data_y)
        curve3.setData(data_z)
    
    def sig_handler(signum, frame):
        sys.exit(0)
    
    if __name__ == "__main__":
        curve_num = 3
        
        signal.signal(signal.SIGINT, sig_handler)
        signal.signal(signal.SIGTERM, sig_handler)
        app = pg.mkQApp()           # App Setup
        win = pg.GraphicsWindow()   # Window Setup
        win.setWindowTitle(u'pyqtgraph chart tool')
        win.resize(900, 600)        #window size
        data_x = array.array('i')
        data_y = array.array('i')
        data_z = array.array('i')
        historyLength = 160 
    
        data_x = np.zeros(historyLength).__array__('d')
        data_y = np.zeros(historyLength).__array__('d')
        data_z = np.zeros(historyLength).__array__('d')
        p = win.addPlot() 
        p.showGrid(x=True, y=True)
        p.setRange(xRange=[0, historyLength], yRange=[-1000, 1000], padding=0)
        p.setLabel(axis='left',     text='y-mag')
        p.setLabel(axis='bottom',   text='x-time')
        p.setTitle('Serial Chart')
        curve1 = p.plot(data_x, pen='r')
        curve2 = p.plot(data_y, pen='g')
        curve3 = p.plot(data_z, pen='b')
        
        portx = 'COM1'
        bps = 115200
        mSerial = serial.Serial(portx, int(bps))
        if (mSerial.isOpen()):
            print("open success")
            mSerial.flushInput()
        else:
            print("open failed")
            serial.close()
        
        #Serial data receive thread
        th1 = threading.Thread(target=Serial)
        th1.setDaemon(True)
        th1.start()
        
        #plot timer define
        timer = pg.QtCore.QTimer()
        timer.timeout.connect(plotData)
        timer.start(10)
        app.exec_()

# 3、实例演示 #

![在这里插入图片描述][8d8d91bd7ea44c8ba34a7952439c622f.gif_pic_center]

# 4、后记 #

之后有时间的话还是希望能够继续完善这个东东，以后也能再能把这玩意当成真正的调试工具来用！  
![在这里插入图片描述][673b880d1c7348deb294dd79f0708168.png_pic_center]

--------------------

参考传送门：

1.  pyqtgraph官网：[https://www.pyqtgraph.org/][https_www.pyqtgraph.org]
2.  博客： [用Python串口实时显示数据并绘图][Python]

[fd0df81721d34841b4c576edb902ee3a.jpg_x-oss-process_pic_center]: /images/20220829/59df4b6d8c7c49718d208a6497abe44f.png
[8d8d91bd7ea44c8ba34a7952439c622f.gif_pic_center]: /images/20220829/e0ca8a7ccc964feaa955e4e96d335233.png
[673b880d1c7348deb294dd79f0708168.png_pic_center]: /images/20220829/730680cd4e62484fbfa952681470742a.png
[https_www.pyqtgraph.org]: https://www.pyqtgraph.org/
[Python]: https://blog.csdn.net/weixin_43389179/article/details/89891895