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Re: EEPROM on i2c Real Time Clock Modules

by roboticus (Chancellor)
on Mar 04, 2015 at 01:29 UTC ( #1118688=note: print w/replies, xml ) Need Help??

in reply to EEPROM on i2c Real Time Clock Modules


Your code looks pretty nice, I'll have to try it out and check the E2PROM on some boards I have. I took a quick look at your code and have a couple suggestions (in no particular order):

  • You can simplify this statement: if ( ( $i + 1 ) / 16 == int( ( $i + 1 ) / 16 ) ) by using the modulo operator (%)--it does an integer division and gives you the remainder. Using it, you could write your statement as:
    if ( ($i+1)%16 == 0).
  • Generally you should declare your variables close to where you use them, in the innermost scope that makes sense. That limits the amount of code you need to review if you're looking for how the variable is used. This is causing you to double-comment certain things, kinda like:
    Line 38:
    my ($i2cBus, $i2cAddr);        # bus ID number & device address
    Line 54:
    #setup bus number, EEPROM address and max eeprom size in bytes $i2cBus = BB_I2C_PERI_1;

    If you declare the variable at the second point, you need only comment it once.

  • You're also commenting on things that need no comment. In the code below the comment we can see that it's setting the baud rate to 100kHz (due to the well-named value). In fact, with well-named variables, many comments are superfluous.
    # set baudrate to 100kHz (AT24C32 at 3.3v, max speed = 100kHz)) $objI2c->set_baudrate( $i2cBus, BB_I2C_CLOCK_100_KHZ );

    The comment about the part's limitations is something I'd put in the comment. If you decide later to use 50kHz because some flakey parts, you don't have to update your comment.

Keep in mind that these are just some trivial suggestions. If one of my colleagues gave me this code, I'd be perfectly happy with it going into production as it is (assuming that it does what it's supposed to). If you review some of my posts here, you'll notice that I frequently post code that could do with improvement as well.


When your only tool is a hammer, all problems look like your thumb.

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Re^2: EEPROM on i2c Real Time Clock Modules
by anita2R (Scribe) on Mar 04, 2015 at 17:53 UTC


    Thank you for taking the time to comment on my script, particularly your 'comments on comments'. I certainly take you point about declaring variables close to where they are first used. It would make it easier to understand and remove my double commenting.

    Thanks also for pointing out an alternative to my clunky code for defining when the output reached a boundary point. I should have worked on that a bit more ... the structure I used occurs four times in that script!



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