René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"i2c.py, ValueError, out of range 0-256 in writing_bytes","articleBody":"Not sure what causes this problem, but I'd though it might be useful to at least post an issue report.\nI tried using the quick2wire library with a cheap accelerometer by running the following code:\n\n``` python\nfrom i2clibraries import i2c_adxl345\nadxl345 = i2c_adxl345.i2c_adxl345(0)\n```\n\nBut immediately I get the following error:\n\n```\nTraceback (most recent call last):\n  File \"./test1.py\", line 6, in \u003cmodule\u003e\n    adxl345 = i2c_adxl345.i2c_adxl345(0)\n  File \"/home/pi/projectfolder/i2clibraries/i2c_adxl345.py\", line 100, in __init__\n    self.setActivityThreshold()\n  File \"/home/pi/projectfolder/i2clibraries/i2c_adxl345.py\", line 178, in setActivityThreshold\n    self.setOption(self.ActivityThreshold, intervals)\n  File \"/home/pi/projectfolder/i2clibraries/i2c_adxl345.py\", line 230, in setOption\n    self.bus.write_byte(register, options)\n  File \"/home/pi/projectfolder/i2clibraries/i2c.py\", line 14, in write_byte\n    writing_bytes(self.addr, *bytes))\n  File \"/home/pi/projectfolder/quick2wire-python-api/quick2wire/i2c.py\", line 97, in writing_bytes\n    return writing(addr, bytes)\n  File \"/home/pi/projectfolder/quick2wire-python-api/quick2wire/i2c.py\", line 108, in writing\n    buf = bytes(byte_seq)\nValueError: bytes must be in range(0, 256)\n```\n\nPrinting these values, I noticed at least one of them indeed isn't in this range: -3\n\nAs a quick hack I changed the function in i2c.py so it clamps the values in byte_seq before returning the message, after which everything works perfectly.\n\n``` python\ndef writing(addr, byte_seq):\n    lst = list(byte_seq)\n    for i in range(0, len(lst)):\n        lst[i] = max(0, min(255, lst[i]))\n    byte_seq = tuple(lst)\n    buf = bytes(byte_seq)\n    return _new_i2c_msg(addr, 0, create_string_buffer(buf, len(buf)))\n```\n","author":{"url":"https://github.com/javl","@type":"Person","name":"javl"},"datePublished":"2013-12-14T16:12:27.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/49/quick2wire-python-api/issues/49"}