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  • I2C Trouble
  • _tkinter.TclError

"The SunFounder Smart Video Car Kit for Raspberry Pi is composed of Raspberry Pi, DC-DC Step-down Voltage Module, USB camera, DC motor driver, and PCA9685-based Servo Controller. From the perspective of software, the smart car is of client/server (C/S) structure. The TCP server program is run on Raspberry Pi for direct control of the car. And the video data are acquired and delivered via the open source software MGPJ-streamer in a real-time manner. The TCP client program is run on PC to send the control command. Both the client and server programs are developed in Python language. The smart car is developed based on the open-source hardware Raspberry Pi and integrates the knowledge of mechanics, electronics, and computer, thus having profound educational significance." [1]

Before you run the client routine, you must first run the server routine.

IOError: [Errno 2] No such file or directory

Error accessing 0x40: Check your I2C address

IOError: [Errno 5] Input/output error

This normally means Raspberry Pi could not find the I2C device. So here's what you can do:

• Hardware problem:
  If you are using a DC adapter for your Raspberry Pi, you need to connect the GND between Servo Controller and Raspberry Pi. Because they are common-grounded by the micro USB, and if you use a DC adapter, you have to make another wire for common-ground.

• Software problem:
  Just Run the i2cHelper.py with

   sudo python i2cHelper.py
  

  And after i2cdetect, and you should see your Servo Controller's address: 0x48

pi@raspberrypi:~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/client $ sudo python cali_client.py
Traceback (most recent call last):
  File "cali_client.py", line 7, in <module>
    top = Tk()   # Create a top window
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1813, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable

This usually happens when you try to run cali_client.py or client_App.py on Raspberry Pi remotely. Like using PuTTy.

• Reason: cali_client.py and client_App.py run under the tkinter, which need a $DISPLAY, usually a GUI. Remotely log in to Raspberry Pi normally under bash, which is a CLI.
• Solution: Try run the cali_client.py and client_App.py directly on your PC or Mac. It needs Python 2.7 installed on your computer. So:
  1. Go to python.org, download the lastest release of Python 2.7 for the operating system you are using, and install.
  2. Go to the github repository, and download the source code by clicking the green button on the right.
  3. Unzip the zip file.
  4. Edit the HOST in cali_client.py or client_App.py with Python IDLE (in Windows, usually, right click the .py file and select "Edit in IDLE"), and select Run => Run Module F5 to run the module.

[1] SunFounder, Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi.