Merge pull request #11 from siddacious/bus_voltage_range_fix

Fixes  #10, fix found by @barbudor, tested and committed by @siddacious

Author: ladyada

adafruit_ina219.py

@@ -175,7 +175,7 @@ def __init__(self, i2c_bus, addr=0x40):
     raw_shunt_voltage       = ROUnaryStruct(_REG_SHUNTVOLTAGE, ">h")
 
     #bus voltage register
-    raw_bus_voltage         = ROBits( 12, _REG_BUSVOLTAGE, 3, 2, False)
+    raw_bus_voltage         = ROBits( 13, _REG_BUSVOLTAGE, 3, 2, False)
     conversion_ready        = ROBit(      _REG_BUSVOLTAGE, 1, 2, False)
     overflow                = ROBit(      _REG_BUSVOLTAGE, 0, 2, False)