Adafruit I2C Library Problem?

Question

I'm having trouble compiling the python from an example in the library.

https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/blob/master/Adafruit_ADS1x15/ads1x15_ex_singleended.py

I basically just cloned the entire repo, navigated to the example and then tried to run it as sudo:

sudo python ./ads1x15_ex_singleended.py

Here is the stack trace:

Traceback (most recent call last):
  File "ads1x15_ex_singleended.py", line 35, in <module>
    adc = ADS1x15(ic=ADS1115)
  File "/home/mename/Developer/AutomatedSmokingMachine/Adafruit-Raspberry-Pi-Python-Code/Adafruit_ADS1x15/Adafruit_ADS1x15.py", line 138, in __init__
    self.i2c = Adafruit_I2C(address)
  File "/home/mename/Developer/AutomatedSmokingMachine/Adafruit-Raspberry-Pi-Python-Code/Adafruit_ADS1x15/Adafruit_I2C.py", line 36, in __init__
    busnum if busnum >= 0 else Adafruit_I2C.getPiI2CBusNumber())
IOError: [Errno 2] No such file or directory

Answer 1

Nevermind. I found the solution in another forum. It turns out that i2c is disabled by default. Follow this guide:

http://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c

# ensure the pi has i2c enabled by adding this to the end of /etc/modules
sudo vim /etc/modules
i2c-bcm2708
i2c-dev

# download and install prerequisites
sudo apt-get update
sudo apt-get install python-smbus
sudo apt-get install i2c-tools

# un-blacklist spi and i2c (disabled by default)
# by commenting out the lines that say
# blacklist spi-bcm2708
# blacklist i2c-bcm2708
sudo vim /etc/modprobe.d/raspi-blacklist.conf

# look for an i2c device on the bus (assuming you have rpi revB)
sudo i2cdetect -y 1

Answer 2

I just wanted to report that today this result can be achieve very easily using this command from the terminal:

sudo raspi-config

In the next screen choose, in order:

1. Interfacing Options
2. I2C

Done that you're good to go.

Happy hacking!

Answer 3

Important to note that in the link that the above answer provided, there is an additional step:

Add the following lines to /boot/config.txt and reboot

dtparam=i2c1=on
dtparam=i2c_arm=on