demo-hcsr04/main.py

#!/usr/bin/env python
import time

from PyQt4 import QtCore, QtGui
from PyQt4.QtGui import QApplication, QMainWindow

import sys, math
import gex

class MyMainScreen(QMainWindow):
    def __init__(self, client=None, parent=None):
        QtGui.QMainWindow.__init__(self, parent)
        self.resize(800, 600)

        self.LINEWIDTH = 1

        self.CAPLEN = 1400
        self.CAPRATE = 115000 # must be > 80 for nyquist

        self.samples_trig = None
        self.samples_echo = None

        self.timer  = QtCore.QTimer(self)
        self.timer.setInterval(10)
        self.timer.timeout.connect(self.measure)
        self.timer.start()
        #
        self.timer2  = QtCore.QTimer(self)
        self.timer2.setInterval(25)
        self.timer2.timeout.connect(self.updatedisp)
        self.timer2.start()

        self.pending = False

        # init GEX
        self.client = client
        self.trig = gex.DOut(client, 'trig')
        self.adc = gex.ADC(client, 'adc')

        self.failcount = 0
        self.skipcount = 0
        self.wantredraw = False

        # self.fcap = gex.FCAP(client, 'fcap')

    def closeEvent(self,event):
        self.timer.stop()
        self.client.close()
        self.close()

    def measure(self):
        if self.pending:
            self.failcount += 1
            if self.failcount > 2:
                self.pending = False
                # self.adc.disarm()
                self.skipcount = 0
            return

        if self.skipcount < 5:
            self.skipcount += 1
            return
        else:
            self.skipcount = 0

        self.pending = True

        self.failcount = 0

        #self.adc.setup_trigger(1, level=2000, edge='rising', count=1366, handler=self.handle_meas)
        #self.adc.arm()

        self.adc.set_sample_rate(self.CAPRATE)
        self.adc.capture(self.CAPLEN, async=True, lst=self.handle_meas)
        self.trig.pulse_us(10)

    def handle_meas(self, rawsamp):
        self.samples_echo = rawsamp[:,0]
        self.samples_trig = rawsamp[:,1]

        # crop
        cropped = False
        for i in range(20, 150):
            if self.samples_echo[i] > 2000:
                # fail
                break

            if self.samples_trig[i] > 2500:
                self.samples_echo = self.samples_echo[i-20:]
                self.samples_trig = self.samples_trig[i-20:]
                cropped = True
                # crop
                break

        if not cropped:
            pass
        else:
            self.wantredraw = True

        self.pending = False

    def updatedisp(self):
        if self.wantredraw:
            self.repaint()
            self.wantredraw = False

    def paintEvent(self, event):
        if self.samples_trig is None:
            return

        W = self.width()
        H = self.height()

        painter = QtGui.QPainter(self)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setRenderHint(QtGui.QPainter.HighQualityAntialiasing)
        painter.fillRect(0,0, W,H, QtCore.Qt.black)

        step = round(W / self.CAPLEN)
        if step == 0:
            step = 1

        color_rx = 0xFFFF00
        color_tx = 0xFF00FF

        # Rx
        mult = 0.17*H/500
        painter.setPen(QtGui.QPen(QtGui.QColor(color_rx), self.LINEWIDTH))
        n = 0
        for i in range(0, W, step):
            if n == len(self.samples_echo) - 1:
                break

            y0 = H - self.samples_echo[n] * mult
            y1 = H - self.samples_echo[n + 1] * mult
            n += 1
            painter.drawLine(QtCore.QLine(i, round(y0), i + step, round(y1)))

        # Tx
        mult = 0.12*H/500
        painter.setPen(QtGui.QPen(QtGui.QColor(color_tx), self.LINEWIDTH))
        n = 0
        for i in range(0, W, step):
            if n == len(self.samples_trig)-1:
                break

            y0 = H - self.samples_trig[n]*mult
            y1 = H - self.samples_trig[n + 1]*mult
            n += 1
            painter.drawLine(QtCore.QLine(i, round(y0), i+step, round(y1)))

        font = painter.font()
        font.setPointSize(22)
        font.setWeight(QtGui.QFont.DemiBold)
        painter.setFont(font)

        # label - Raw HC-SR04 signal
        painter.drawText(W-170, 50, "Vysílač")

        painter.setPen(QtGui.QPen(QtGui.QColor(color_rx), 2))
        painter.drawText(W-170, 85, "Přijímač")

        painter.setPen(QtGui.QPen(QtGui.QColor(0xFFFFFF), 2))
        painter.drawText(round(W/2)-220, 50, "Ultrazvukový dálkoměr HC-SR04")

with gex.Client(gex.TrxSerialThread()) as client:
    app = QApplication(sys.argv)
    mainscreen = MyMainScreen(client)
    mainscreen.showFullScreen()
    #mainscreen.show()
    app.exec_()