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-   -   I2C Error on read() or write() (http://www.chiefdelphi.com/forums/showthread.php?t=143666)

nickbrickmaster 11-02-2016 19:24
I2C Error on read() or write()
 
I'm trying to use the ITG3200 gyro on the AndyMark breakout board (am-2314). I translated some code I found from Java to Python, which you can find on PasteBin below, along with the original.

I'm getting the below error when both using my custom ITG3200 class and the ADXL345_I2C class.

Code:
Traceback (most recent call last):
  File "/home/lvuser/py/robot.py", line 268, in <module>
    wpilib.run(MyRobot)
  File "/usr/local/lib/python3.5/site-packages/wpilib/_impl/main.py", line 101, in run
    retval = options.cmdobj.run(options, robot_class, **kwargs)
  File "/usr/local/lib/python3.5/site-packages/hal/main.py", line 11, in run
    return robot_class.main(robot_class)
  File "/usr/local/lib/python3.5/site-packages/wpilib/robotbase.py", line 178, in main
    robot.startCompetition()
  File "/usr/local/lib/python3.5/site-packages/wpilib/iterativerobot.py", line 78, in startCompetition
    self.robotInit()
  File "/home/lvuser/py/robot.py", line 252, in robotInit
    self.subsystems['drive'] = DriveSubsystem()
  File "/home/lvuser/py/robot.py", line 39, in __init__
    self.gyro.init()
  File "/home/lvuser/py/ITG3200.py", line 142, in init
    if not self.testConnection():
  File "/home/lvuser/py/ITG3200.py", line 236, in testConnection
    return self.getDeviceID() == 0b110100
  File "/home/lvuser/py/ITG3200.py", line 246, in getDeviceID
    return self.getRegisterBits(RA_WHO_AM_I, DEVID_BIT, DEVID_LENGTH)
  File "/home/lvuser/py/ITG3200.py", line 268, in getRegisterBits
    containingByte = self.getRegisterByte(register)
  File "/home/lvuser/py/ITG3200.py", line 265, in getRegisterByte
    return self.readI2C(register, 1)[0]
  File "/home/lvuser/py/ITG3200.py", line 83, in readI2C
    return self.i2c.read(register, count)
  File "/usr/local/lib/python3.5/site-packages/wpilib/i2c.py", line 145, in read
    return self.transaction([registerAddress], count)
  File "/usr/local/lib/python3.5/site-packages/wpilib/i2c.py", line 84, in transaction
    dataToSend, receiveSize)
  File "/usr/local/lib/python3.5/site-packages/hal/functions.py", line 407, in i2CTransaction
    raise IOError(_os.strerror(C.get_errno()))
OSError: Success
The gyro works in Java using the original, but I find it strange that the accelerometer produces the same error. I've verified the addresses and the other numbers.

My translated code:
http://pastebin.com/CKr5prZs

Original:
https://github.com/bussell/SparkFun6...roITG3200.java

RobotPy is 2016.2.0 on robot and driver station.
Is this a bug in robotpy or am I messing up somewhere?

Thanks for the help.

virtuald 12-02-2016 00:48
Re: I2C Error on read() or write()
 
Quote:
Originally Posted by nickbrickmaster (Post 1538836)
RobotPy is 2016.2.0 on robot and driver station.
Is this a bug in robotpy or am I messing up somewhere?

Thanks for the help.
It very well could be a bug in RobotPy, the i2c interface isn't particularly well tested -- though, I was able to talk to the NavX device via I2C without any issues.

What value are you passing in for 'port' to the I2C constructor? I ask because I see that in HAL it checks to see if port < 0, and returns -1 if so -- which wouldn't set errno (and perhaps why you're seeing the 'success' message). I'll add a check for that so it can't happen in the future...

This error also reminds me of this bug that someone reported for WPILib.

virtuald 12-02-2016 00:56
Re: I2C Error on read() or write()
 
Also, once this works, it'd make for a nice pull request to robotpy-wpilib-utilities. Just saying. :)

virtuald 12-02-2016 01:27
Re: I2C Error on read() or write()
 
Another thought. The java I2C function does not throw if there's an error, it just returns true. Can you add some error checking to the java code (maybe throw an exception if it returns false from i2c.read?), rerun it, and see if you get an error?

nickbrickmaster 12-02-2016 08:11
Re: I2C Error on read() or write()
 
Thanks for the suggestions. The port is I2C.Port.kOnboard. I don't have access to the robot at the moment, but I'll test the Java code later.

nickbrickmaster 12-02-2016 21:36
Re: I2C Error on read() or write()
 
Thanks for the help. Turns out that I had connected the board incorrectly, and that the data I was getting from Java was random noise, which I did not get in Python because I never ran initialize() in Java.

Again, thanks for the help. I got the gyro working. It still throws an error every once in a while (but good data otherwise), which the code catches and replaces with an array of zeroes. I'd like a better solution, and to get to the bottom of the I2C errors, but that is a project for later. I'll definitely add it to robotpy-wpilib-utilities once decoding and calibration is all figured out.


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