RC circuit demo

RC circuit demo (current and voltage only) ported to python.

rc.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python2
+# Example driver for Pixelpulse
+# Distributed under the terms of the BSD License
+# (C) 2011 Kevin Mehall (Nonolith Labs) <[email protected]>
+
+import math, time
+import pixelpulse
+import webbrowser
+
+class RCDevice(pixelpulse.Device):
+
+	def __init__(self):
+		self.v = 0
+		self.i = 0
+		self.q = 0
+		self.r = 100.0
+		self.c = 10e-3
+
+		# Define the channels
+		self.voltage = pixelpulse.AnalogChannel(
+			name='voltage',
+			unit='V',
+			min=-5.0,
+			max=5.0,
+			state='source',
+			stateOptions=['source','measure'],
+			# Graph is initially shown. If False, the channel will be on the bottom bar
+			showGraph=True,
+			onSet=self.setChannel,
+		)
+
+		self.current = pixelpulse.AnalogChannel(
+			name='current',
+			unit='mA',
+			min=-200,
+			max=200,
+			state='measure',
+			stateOptions=['source','measure'],
+			showGraph=True,
+			onSet=self.setChannel,
+		)
+
+		# pixelpulse reads this property to determine which channels to show
+		self.channels = [self.voltage, self.current]
+
+		self.source = self.voltage
+
+		self.lastTime = time.time()
+
+	def start(self, server):
+		""" This method is called by Pixelpulse once the server is started """
+		server.poll(self.update) # ask the server to poll our update() method at its default sample rate
+
+	def update(self):
+		""" Polled to update the data as configured in start(). Returns a list of (channel. value) pairs """
+		self.t = time.time()
+		self.dt = self.t-self.lastTime
+		self.lastTime = self.t
+		if self.source == self.voltage:
+			self.i = (self.v-self.q/self.c)/self.r
+		else:
+			self.v = self.q/self.c
+		if (self.v>=5 and self.i>0) or (self.v<=-5 and self.i<0):
+			self.i=0
+		self.q += self.i*self.dt
+		return [
+			(self.voltage, self.v),
+			(self.current, self.i*1000),
+		]
+
+	def setChannel(self, channel, value, state):
+		if channel == self.voltage:
+			if state == 'source' and value != None:
+				self.v=value
+				self.source = self.voltage
+		elif channel == self.current:
+			if state == 'source' and value != None:
+				self.i=value/1000
+		else:
+			return
+
+		if state == 'source' and self.source != channel:
+			self.source = channel
+		if state == 'measure':
+			if self.source == self.voltage:
+				self.source = self.current
+			if self.source == self.current:
+				self.source = self.voltage
+
+		if self.source == self.voltage:
+			self.voltage.setState('source')
+			self.current.setState('measure')
+		else:
+			self.current.setState('source')
+			self.voltage.setState('measure')
+
+if __name__ == '__main__':
+	dev = RCDevice()
+	server = pixelpulse.DataServer(dev)
+	server.start(openWebBrowser=True)