raspberrypiでADS1015を使用したい

前提・実現したいこと

raspberry piでADS1015(A-Dコンバータ)を使用しようとしています。

最終的にraspberry　piで距離センサを使用したいです。

Adafruitのサイトを参考に、サンプルプログラム(Adafruitのもの)を
実行しましたがエラーが起き、解決方法が判らず
教えていただけないでしょうか。

発生している問題・エラーメッセージ

Reading ADS1x15 values, press Ctrl-C to quit...
|      0 |      1 |      2 |      3 |
-------------------------------------
Traceback (most recent call last):
  File "simpletest.py", line 42, in <module>
    values[i] = adc.read_adc(i, gain=GAIN)
  File "/usr/local/lib/python3.5/dist-packages/Adafruit_ADS1x15-1.0.2-py3.5.egg/Adafruit_ADS1x15/ADS1x15.py", line 192, in read_adc
  File "/usr/local/lib/python3.5/dist-packages/Adafruit_ADS1x15-1.0.2-py3.5.egg/Adafruit_ADS1x15/ADS1x15.py", line 128, in _read
  File "/usr/local/lib/python3.5/dist-packages/Adafruit_GPIO-1.0.4-py3.5.egg/Adafruit_GPIO/I2C.py", line 129, in writeList
  File "/usr/local/lib/python3.5/dist-packages/Adafruit_PureIO-1.1.5-py3.5.egg/Adafruit_PureIO/smbus.py", line 363, in write_i2c_block_data
  File "/usr/local/lib/python3.5/dist-packages/Adafruit_PureIO-1.1.5-py3.5.egg/Adafruit_PureIO/smbus.py", line 163, in _select_device
OSError: [Errno 16] Device or resource busy

該当のソースコード

以下、実行したプログラムです。

python
1# Simple demo of reading each analog input from the ADS1x15 and printing it to
2# the screen.
3# Author: Tony DiCola
4# License: Public Domain
5import time
6
7# Import the ADS1x15 module.
8import Adafruit_ADS1x15
9
10
11# Create an ADS1115 ADC (16-bit) instance.
12adc = Adafruit_ADS1x15.ADS1115()
13
14# Or create an ADS1015 ADC (12-bit) instance.
15#adc = Adafruit_ADS1x15.ADS1015()
16
17# Note you can change the I2C address from its default (0x48), and/or the I2C
18# bus by passing in these optional parameters:
19#adc = Adafruit_ADS1x15.ADS1015(address=0x49, busnum=1)
20
21# Choose a gain of 1 for reading voltages from 0 to 4.09V.
22# Or pick a different gain to change the range of voltages that are read:
23#  - 2/3 = +/-6.144V
24#  -   1 = +/-4.096V
25#  -   2 = +/-2.048V
26#  -   4 = +/-1.024V
27#  -   8 = +/-0.512V
28#  -  16 = +/-0.256V
29# See table 3 in the ADS1015/ADS1115 datasheet for more info on gain.
30GAIN = 1
31
32print('Reading ADS1x15 values, press Ctrl-C to quit...')
33# Print nice channel column headers.
34print('| {0:>6} | {1:>6} | {2:>6} | {3:>6} |'.format(*range(4)))
35print('-' * 37)
36# Main loop.
37while True:
38    # Read all the ADC channel values in a list.
39    values = [0]*4
40    for i in range(4):
41        # Read the specified ADC channel using the previously set gain value.
42        values[i] = adc.read_adc(i, gain=GAIN)
43        # Note you can also pass in an optional data_rate parameter that controls
44        # the ADC conversion time (in samples/second). Each chip has a different
45        # set of allowed data rate values, see datasheet Table 9 config register
46        # DR bit values.
47        #values[i] = adc.read_adc(i, gain=GAIN, data_rate=128)
48        # Each value will be a 12 or 16 bit signed integer value depending on the
49        # ADC (ADS1015 = 12-bit, ADS1115 = 16-bit).
50    # Print the ADC values.
51    print('| {0:>6} | {1:>6} | {2:>6} | {3:>6} |'.format(*values))
52    # Pause for half a second.
53    time.sleep(0.5)ソースコード