Author Topic: Munged Pocket Scroller  (Read 255 times)

Offline TxBillbr

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Munged Pocket Scroller
« on: December 20, 2018, 01:15:04 PM »
I thought I posted this a couple of days ago but can't find the post, so re-posting (apologies if it is duplicated). I was working with my TuneTo sign changing from a 1x4 to a 2x2 and in doing so I managed to kill something in the scroller or pocket beagle. On display testing I only get red to illuminate. Is it likely the beagle or the SN74HCT541? (or both?)  I have ordered a couple of chips from Mouser, but that will take a couple of days to get here. I can get my hands on a friend's beagle but don't really want to solder a socket on his board unless I need to. Any suggestions from folks? I thought about getting the fluke out and powering up the scroller without anything attached, then probing each output pin while pulling up the input pin. I have a dangerous level of knowledge at the hardware level, so wanted to ask before leaping.


That's what I get for trying to change stuff this late in the season.  ::)


Bill
P.S. I hooked a panel to an adafruit pi-hat and verified the panels are ok. I would use the adafruit interface, but it only support 32x and 64x format panels. I have 16x32 1/8 scan P10s
« Last Edit: December 20, 2018, 02:03:25 PM by TxBillbr »

Offline dkulp

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Re: Munged Pocket Scroller
« Reply #1 on: December 20, 2018, 02:12:20 PM »
If it's just one color, it's most likely the beagle.   The color lines are directly attached and not buffered. 


That said, each socket has a separate set of color lines.  Thus, just moving from one socket to another should fix it.  If you fried a GPIO on one port, the other ports shouldn't be affected.   

Dan Kulp

Offline pixelpuppy

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Re: Munged Pocket Scroller
« Reply #2 on: December 20, 2018, 02:18:33 PM »
If it's just one color, it's most likely the beagle.   The color lines are directly attached and not buffered. 
Dan it that true for both the Pocket Scroller and the regular BB scroller?    Asking for a friend  ;)
-Mark

Offline dkulp

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Re: Munged Pocket Scroller
« Reply #3 on: December 20, 2018, 02:42:57 PM »
If it's just one color, it's most likely the beagle.   The color lines are directly attached and not buffered. 
Dan it that true for both the Pocket Scroller and the regular BB scroller?    Asking for a friend  ;)


Yes.   For almost all of scrollers we just use a single buffer chip.  That chip is used for the clock/OE/latch and address lines as those lines need to fan out to all ports.   The GPIO lines cannot fan out enough so the buffer chip is needed.  For the rest of the line, we go directly from the GPIO to the socket.  One of the vendors (Ron maybe?) had a version of the Octo that buffered everything, but it added $8 or more to the board for no discernible visual difference so I don't think anyone purchased them. 






Offline JonB256

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Re: Munged Pocket Scroller
« Reply #4 on: December 20, 2018, 08:12:14 PM »
One of the vendors (Ron maybe?) had a version of the Octo that buffered everything, but it added $8 or more to the board for no discernible visual difference so I don't think anyone purchased them.

Wrong!  I bought two of them. Assembled one and it is running right now. I don't remember which panel and can't tell the difference. :)

 

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