Marin Purgar

#!/usr/bin/python
# -*- coding: utf-8 -*-
# Author: Marin Purgar - marin.purgar@gmail.com
# This code is freeware, do whatever you want with it!

# Imports

import sys
import usb

from PyQt4 import QtCore, QtGui

# Classes

# AnalogMultimeter

class AnalogMultimeter(QtGui.QWidget):
  needlePosition = 0
  needlePolygon = QtGui.QPolygon([QtCore.QPoint(2, -8), QtCore.QPoint(-2, -8), QtCore.QPoint(-1, 96), QtCore.QPoint(1, 96), ])

  def __init__(self, parent=None):
    super(AnalogMultimeter, self).__init__(parent)
    self.setWindowTitle("Analog Multimeter")
    self.resize(220, 140)

  def paintEvent(self, event):
    width = self.width()
    height = self.height()
    painter = QtGui.QPainter(self)
    painter.setRenderHint(QtGui.QPainter.Antialiasing)
    painter.translate(width / 2, height * 0.85)
    painter.scale(width / 220.0, height / 140.0)
# paint arc
    painter.setPen(QtGui.QPen(QtCore.Qt.gray, 1, QtCore.Qt.SolidLine))
    painter.drawArc(-88, -88, 176, 176, 20 * 16, 140 * 16)
# paint big ticks
    painter.setPen(QtGui.QPen(QtCore.Qt.black, 1, QtCore.Qt.SolidLine))
    painter.setFont(QtGui.QFont('Arial', 8))
    painter.rotate(200);
    for i in range(11):
      painter.drawLine(88, 0, 96, 0)
      if (i % 2) == 0:
        painter.save()
        painter.translate(98, -15)
        painter.rotate(90);
        painter.drawText(0, -10, 30, 10, QtCore.Qt.AlignCenter, str(i / 2))
        painter.restore()
      painter.rotate(14)
# paint small ticks
    painter.setPen(QtCore.Qt.gray)
    painter.rotate(206);
    for i in range(50):
      if (i % 5) != 0:
        painter.drawLine(88, 0, 92, 0)
      painter.rotate(2.8)
# paint needle
    painter.rotate(130 + self.needlePosition)
    painter.setPen(QtCore.Qt.NoPen)
    painter.setBrush(QtCore.Qt.red)
    painter.drawConvexPolygon(AnalogMultimeter.needlePolygon)
    painter.end()

  def updatePosition(self, position):
    if position != self.needlePosition:
      self.needlePosition = position
      self.repaint()

# Pinguino

class Pinguino():
  VENDOR = 0x04D8
  PRODUCT = 0xFEAA
  CONFIGURATION = 3
  INTERFACE = 0
  ENDPOINT_IN = 0x82
  ENDPOINT_OUT = 0x01

  device = None
  handle = None

  def __init__(self,):
    for bus in usb.busses():
      for dev in bus.devices:
        if dev.idVendor == self.VENDOR and dev.idProduct == self.PRODUCT:
          self.device = dev
    return None

  def open(self):
    if not self.device:
      print >> sys.stderr, "Unable to find device!"
      return None
    try:
      self.handle = self.device.open()
      self.handle.setConfiguration(self.CONFIGURATION)
      self.handle.claimInterface(self.INTERFACE)
    except usb.USBError, err:
      print >> sys.stderr, err
      self.handle = None
    return self.handle

  def close(self):
    try:
      self.handle.releaseInterface()
    except Exception, err:
      print >> sys.stderr, err
    self.handle, self.device = None, None

  def read(self, length, timeout = 0):
    return self.handle.bulkRead(self.ENDPOINT_IN, length, timeout)

  def write(self, buffer, timeout = 0):
    return self.handle.bulkWrite(self.ENDPOINT_OUT, buffer, timeout)

# Main methods

def updateMeter():
  usb_in = ''
  try:
    usb_in = pinguino.read(2, 1);
  except usb.USBError as err:
    pass
  if len(usb_in) > 0:
    i = usb_in[0] * 256 + usb_in[1];
    j = int(i * 140 / 1023.0 * 100) / 100.0
    meter.updatePosition(j)

# Main

app = QtGui.QApplication(sys.argv)

meter = AnalogMultimeter()
meter.show()

pinguino = Pinguino()

if pinguino.open() == None:
  print "Unable to open Pinguino device!"
  sys.exit()

timer = QtCore.QTimer()
timer.timeout.connect(updateMeter)
timer.start(10)

sys.exit(app.exec_())

# EOF