first commit

Software/Python/grove_compass_lib.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python
+#
+# GrovePi Library for using the Grove Compass module HCM5883 (http://www.seeedstudio.com/depot/Grove-3Axis-Digital-Compass-p-759.html)
+#
+# The GrovePi connects the Raspberry Pi and Grove sensors.  You can learn more about GrovePi here:  http://www.dexterindustries.com/GrovePi
+#
+# Have a question about this example?  Ask on the forums here:  http://forum.dexterindustries.com/c/grovepi
+#
+'''
+## License
+
+The MIT License (MIT)
+
+GrovePi for the Raspberry Pi: an open source platform for connecting Grove Sensors to the Raspberry Pi.
+Copyright (C) 2017  Dexter Industries
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+'''               
+# History
+# ------------------------------------------------
+# Author     Date      		Comments
+# Karan      22 July 14  	Initial Authoring
+# 	
+# NOTE:		                                                              
+# Refer to the datasheet to add additional functionality https://www.seeedstudio.com/wiki/images/4/42/HMC5883.pdf
+
+import smbus
+import time
+import math
+import RPi.GPIO as GPIO
+import struct
+
+rev = GPIO.RPI_REVISION
+if rev == 2 or rev == 3:
+    bus = smbus.SMBus(1)
+else:
+    bus = smbus.SMBus(0)
+	
+HMC5883L_ADDRESS            =0x1E
+
+#CONFIGURATION_REGISTERA     =0x00
+#CONFIGURATION_REGISTERB     =0x01
+MODE_REGISTER               =0x02
+#DATA_REGISTER_BEGIN         =0x03
+
+#MEASUREMENT_CONTINUOUS      =0x00
+#MEASUREMENT_SINGLE_SHOT     =0x01
+#MEASUREMENT_IDLE            =0x03
+
+#Do two's compiment of val (for parsing the input)
+#http://stackoverflow.com/a/9147327/1945052
+def twos_comp(val, bits):
+	"""compute the 2's compliment of int value val"""
+	if( (val&(1<<(bits-1))) != 0 ):
+		val = val - (1<<bits)
+	return val
+
+#Compass class for all the values and functions
+class compass:
+	x=0
+	y=0
+	z=0
+	heading=0
+	headingDegrees=0
+	
+	def __init__(self):
+		#Enable the compass
+		bus.write_byte_data(HMC5883L_ADDRESS,MODE_REGISTER,0)
+		time.sleep(.1)
+		data=bus.read_i2c_block_data(HMC5883L_ADDRESS,0)
+		compass.update(self)
+	
+	#Update the compass values
+	def update(self):
+		data=bus.read_i2c_block_data(HMC5883L_ADDRESS,0)
+		compass.x=twos_comp(data[3]*256+data[4],16)
+		compass.z=twos_comp(data[5]*256+data[6],16)
+		compass.y=twos_comp(data[7]*256+data[8],16)
+		compass.heading=math.atan2(compass.y, compass.x)
+		if compass.heading <0:
+			compass.heading+=2*math.pi
+		if compass.heading >2*math.pi:
+			compass.heading-=2*math.pi
+		
+		compass.headingDegrees=round(math.degrees(compass.heading),2)
+