P2 firmware bug

Discussion in 'EthConGateway by Joshua 1 Systems' started by AAH, Feb 21, 2014.

  1. AAH

    AAH I love blinky lights :) Community Project Designer

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    A bit of background first. I used my P2 all Xmas 2013 with 1 output driving my 170 2811 pixels. Yesterday a legend in Xmas lighting did some damage to her P2 while testing so I am now very gun shy when connecting up. As a result I hooked my oscilloscope to my P2 in preparation to testing my new 2801DC boards. I was going to leave output 1 as 2811 and run 2801 on output 2. I checked that I was getting an output in preparation to hook up my board. I noticed that the 2811 output had both data and clock being pumped out (2811 doesn't need this) and the 2801 output had data only (it needs data and clock). I swapped backwards and forwards between 2801 and 2811 several times on both outputs and each time I got the result. It was getting late last night so I thought I may have been a bit punchy so I gave up. Today I have tested and tested further and even reflashed the P2. It had and has the latest version which is 2.7. I didn't erase the P2 first but after getting the same results I will whilst waiting for a reply. Below are some terrible photos which show the output waveforms of the data and clock outputs followed by the string config. The 1st is what I got with 2811 and then with 2801.
    The cro photo was taken seconds before the lappy picture in each case and I had done the save and reboot process to make the changes stick.
     

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  2. j1sys

    j1sys There are no rules, and those are the rules. Community Project Designer

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    No bug. WS281x does indeed create a clock signal that is unused.

    2801 does have both or it won't work. On a P2 it is a physical connection through a 541 driver and 300 ohm current limiter. Perhaps your output is blown on one string.

    I personally test all ports on all pixel devices before shipping with a string of 8 2801 pixels that hangs by my computer. If it works, both clock and data have to be working.

    Ed
     
  3. OP
    OP
    AAH

    AAH I love blinky lights :) Community Project Designer

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    I've checked on both sides of the 300R resistor and other than a bit of rounding the signal is the same. With more testing I worked out to replicate the bug. When all zeroes are getting sent to the P2 it turns off the clock regardless of packets being sent to it. If I wasn't being so cautious with connecting up to the board I wouldn't have even noticed that this occurs.
     

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