<![CDATA[Time to dust off this thread!]]>RE: https://chaosfurs.social/@cato/116563857284574318

Time to dust off this thread! I have now - motivated by a looming deadline, because I promised this display for an event this weekend - managed to make a custom control board and integrate it into my existing software framework!

]]>https://board.circlewithadot.net/topic/3b868563-ddad-47ac-b07d-a7fded3b7362/time-to-dust-off-this-threadRSS for NodeFri, 15 May 2026 05:01:20 GMTTue, 12 May 2026 22:01:58 GMT60<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 22:02:48 GMT]]>Pulldown resistors fixed that too!

Next: Fix the broken first row - turns out this was just some broken solder joints. Easy fix. The soldering quality in this display is shockingly poor. But it was a lab / development device after all.

Also gave it a good clean, looks much nicer now!

Now all that's left to do is replace the little potentiometer with a proper brightnes ssensor and wire my board up to the ballasts for dimming.

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569523395619737https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569523395619737Wed, 13 May 2026 22:02:48 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 20:59:14 GMT]]>@cato@chaosfurs.social ​​

]]>https://board.circlewithadot.net/post/https://shonk.sam.ax/notes/am83wvmapjwz01enhttps://board.circlewithadot.net/post/https://shonk.sam.ax/notes/am83wvmapjwz01enWed, 13 May 2026 20:59:14 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 20:57:41 GMT]]>Next problem: The alternating blinkers next to each row seem to not turn off fully. I already identified this as being caused by the fluorescent tubes inside the display radiating into the ribbon cables (they're just kinda loose inside) and my board missing pulldown resistors. My blinker control uses two shift registers with parallel data but opposite output enables to alternate between left and right and I forgot that enable = low means high-impedance, not low outputs.

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569267361216292https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569267361216292Wed, 13 May 2026 20:57:41 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 20:27:17 GMT]]>@thiccpaws thank you! :3

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569147806736372https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569147806736372Wed, 13 May 2026 20:27:17 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 20:12:27 GMT]]>@cato This is so cool!

]]>https://board.circlewithadot.net/post/https://tech.lgbt/users/thiccpaws/statuses/116569089464202872https://board.circlewithadot.net/post/https://tech.lgbt/users/thiccpaws/statuses/116569089464202872Wed, 13 May 2026 20:12:27 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 20:03:00 GMT]]>@mist yeah no idea, seems like that module might have been replaced and has a slightly different tone

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569052337212954https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116569052337212954Wed, 13 May 2026 20:03:00 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:41:07 GMT]]>@cato good noms, why is the last word orangy?

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/mist/statuses/116568966245009814https://board.circlewithadot.net/post/https://chaosfurs.social/users/mist/statuses/116568966245009814Wed, 13 May 2026 19:41:07 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:22:11 GMT]]>@Citali thanks 😄

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568891839120965https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568891839120965Wed, 13 May 2026 19:22:11 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:21:20 GMT]]>@cato happy eating :3

]]>https://board.circlewithadot.net/post/https://fellies.social/users/Citali/statuses/116568888445123482https://board.circlewithadot.net/post/https://fellies.social/users/Citali/statuses/116568888445123482Wed, 13 May 2026 19:21:20 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:20:37 GMT]]>

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]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568885689786425https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568885689786425Wed, 13 May 2026 19:20:37 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:03:01 GMT]]>why?? I tested with Arduino's shiftOut weeks ago and it worked?? Isn't shiftOut also mode 0?

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568816463785458https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568816463785458Wed, 13 May 2026 19:03:01 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 19:02:32 GMT]]>i.

i switched the clock phase (SPI mode 1 instead of 0)

and it works

i can't

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568814560267970https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568814560267970Wed, 13 May 2026 19:02:32 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 18:22:04 GMT]]>I did confirm with the oscilloscope that what the LCD is receiving is valid data now and that the data matches what it should be. So the bit shift must have occurred outside of the timeframe I sampled with the scope

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568655406275841https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568655406275841Wed, 13 May 2026 18:22:04 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 18:20:42 GMT]]>I extended my font generator thingy to allow the reverse operation, i.e. entering bytes and showing what they would look like on the LCD. I then added a function to shift the data bit by bit, and tried it with the character I am trying to send (5), and of course - one left shift and I get exactly the garbled characters I am seeing on the display. So that is what's happening. Somehow there is a single bit shift in all of the data

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568650060460941https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568650060460941Wed, 13 May 2026 18:20:42 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 16:55:24 GMT]]>330R on both data and clock - data is acceptable, but clock is way too weak. It still registers though! Still showing garbage anyway. But now the data out doesn't keep losing bits 😄
Gonna try 100R on clock and leave it at 330R for data.

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]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568314661684500https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568314661684500Wed, 13 May 2026 16:55:24 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 15:52:08 GMT]]>let's play around with some series termination

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568065883593899https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568065883593899Wed, 13 May 2026 15:52:08 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 15:51:53 GMT]]>pretty sure the clock (red) shouldn't have hiccups like this

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]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568064868260169https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568064868260169Wed, 13 May 2026 15:51:53 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 15:46:50 GMT]]>(also yay, finally managed to get my PicoScope to work in Linux. One less reason to boot up the old Windows install)

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568045042101549https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568045042101549Wed, 13 May 2026 15:46:50 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 15:46:26 GMT]]>New insights: It must be a signal integrity issue where the LCDs can't get the data quite right. See this capture. Red is clock, blue is data input, brown is data output, green is latch (irrelevant here). I am sending the same data across the whole display so even thouth the output lags behind 10 characters (600 bits), it SHOULD be the same pattern. Every group of HIGH bits is shortened by one bit.

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]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568043445852252https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116568043445852252Wed, 13 May 2026 15:46:26 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 06:17:36 GMT]]>@Foxotronic yeah I measured at the source because it's easier but I was pretty tired, I'll do some more measurements today. Can't say if it happens while measuring yet

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116565806734110587https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116565806734110587Wed, 13 May 2026 06:17:36 GMT<![CDATA[Reply to Time to dust off this thread! on Wed, 13 May 2026 06:01:47 GMT]]>@cato without knowing the circuity; do they may interfere via ground/chassis?
Where do you measure the signals: next to the source or next to the sink?
Are the glitches also present while measuring?
How do you even measure? What propes do you use?

(Don't expect an expert discussion from me – those are merely ideas where i would suspected sources of errors while not knowing anything)

]]>https://board.circlewithadot.net/post/https://anubis.social/users/Foxotronic/statuses/116565744502929454https://board.circlewithadot.net/post/https://anubis.social/users/Foxotronic/statuses/116565744502929454Wed, 13 May 2026 06:01:47 GMT<![CDATA[Reply to Time to dust off this thread! on Tue, 12 May 2026 23:42:54 GMT]]>There seems to be some sort of problem once more than 4 LCD buses are plugged in. But measuring the shared signal lines, the signal levels and edges as well as the power rails look totally fine, so it's not just the driver being too weak...?
It fails in a repeatable, consistent way too, so random glitches seem very unlikely.
Even at a comically slow 5 kHz clock it still fails.
But enough for today, I really need to sleep

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116564254674617819https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116564254674617819Tue, 12 May 2026 23:42:54 GMT<![CDATA[Reply to Time to dust off this thread! on Tue, 12 May 2026 23:17:15 GMT]]>Aaaand I'm in integration hell

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116564153843731943https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116564153843731943Tue, 12 May 2026 23:17:15 GMT<![CDATA[Reply to Time to dust off this thread! on Tue, 12 May 2026 22:16:06 GMT]]>The alternating blinker control also works!

]]>https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116563913385216040https://board.circlewithadot.net/post/https://chaosfurs.social/users/cato/statuses/116563913385216040Tue, 12 May 2026 22:16:06 GMT