5 ms·

Oldskool Demo on a 7 Segment Display

141 points by fourspace 10y ago

lukas 10y ago
This is awesome. Thanks for sharing.
jackhammons 10y ago
Very pretty. Nice effect!
ajnin 10y ago
It's amusing but a bit underwhelming, he's simply mapping a grid of pixels to segments, he's not taking the shape and orientation of the segments into account at all.
- dang 10y ago
  This style of comment isn't very good here because it comes across as putting down someone else's work. Some of that is just cultural and linguistic convention, of course, but on HN it's important; we know from long experience how it affects the community. It would be easy to rework this into a good comment by expressing your point additively rather than as fault-finding. For example, mention "shape and orientation of the segments" as the next thing to take into account and add some information about how one might do that. Then you're helping all of us learn.
- vegabook 10y ago
  Actually I think the nonlinear and binary mapping is what gives this quite an artistic effect. Reminded me of the predator self destruct countdown.
i336_ 10y ago
This is ever so slightly thread-hijacking but I've been wondering something slightly related for a while now: what's the downright cheapest way to get into really really big LED matrixes? Like the kind used for signs (of various sizes; let's say I'm referring to around <2ft sq). The major issue I'm completely ignorant of is how to get enough I/O that can drive the LEDs directly - I'm assuming something with lots of direct drive I/O and no intermediary components would be the cheapest way to do it (?). I understand multiplexing is the only way to survive at scale, but for small displays (say, 5x30 (= 150 LEDs)), what solutions would have enough I/O to drive each LED emitter individually, without scanning? I've always wondered what a truly flickerless LED matrix would look like. * (* Several years ago I had an odd incident where after using a scientific calculator I'd see weird swirling patterns overlaid on top of whatever I was looking at. The LCD itself was not faulty or damaged, and I couldn't see any flickering at all. Considering LCDs run at 30-100Hz, the whole incident (it stopped after a while, I have some theories as to why) made me curious what a truly DC-driven LED matrix would look like.)
- bombela 10y ago
  Some LEDs have an integrated chip, making it easy to daisy chain them as a big shift register. Example: https://www.adafruit.com/product/2343 https://www.adafruit.com/product/2343 You can find many similar type of LED in strips, trough holes etc. Some are faster than others. Addressable strips can be used to make big displays it seems: http://hackaday.com/2013/02/25/building-huge-displays-with-led-strips/ http://hackaday.com/2013/02/25/building-huge-displays-with-l...
- ChuckMcM 10y ago
  As it turns out this is getting pretty easy. A de-facto standard has emerged for these[1] LED modules, both in interfacing and in mounting. I used a couple in a LED clock[2] which can also tell time in QR Code[3] :-). Basically at $25 each you're looking at $3,750 in modules for a 640 x 480 display that in the "P3" (3mm dot pitch) size would be 1.92M wide (75.6") by 1.44M tall (56.7"). All of the LED driving is taken care of by the module, except for multiplexing the 'lines'. So these work by having drivers for one 'line' or LEDs (or 2 lines on the 32 LED high modules). You shift out the bits to them on a 16 pin plug. My clock as using an STM32F4 chip on a 1Bitsy[4] and was doing 240 FPS. Since these micros can be easily paralleled and synchronized you can drive an arbitrarily large sign by adding about $25 per 16 panels. Feeding them all data is a bit more complicated but not terribly so. [1] https://www.aliexpress.com/item/3mm-Indoor-SMD0606-rgb-led-display-module-192mm-x-96mm-64-32-pixle-Video-images-picture/1641364020.html?ws_ab_test=searchweb0_0,searchweb201602_3_10065_10000073_10068_10501_10000077_10000074_10503_10000032_119_10000030_10000026_10000023_431_10000069_10000068_10060_10062_10056_10055_10000062_10054_10000063_10059_10099_10000020_10000013_10103_10102_10000016_10096_10000056_10000059_10052_10053_10107_10050_10051_10106_10000097_10000094_10000091_10000007_10000050_10084_10000101_10083_10000100_10080_10000047_10000104_10082_10081_10110_10111_10112_10113_10114_10000089_10000086_10000083_10000041_10000044_10000080_10078_10079_10000038_10073_10000035_10070_10122_10123_10121_10126_10124-10503_10501,searchweb201603_2,afswitch_3,ppcSwitch_1,single_sort_1_default&btsid=0207e271-5f2c-489f-be15-a3aced211e7a&algo_expid=0eab590f-806a-4601-9f5c-1656aa91ca24-0&algo_pvid=0eab590f-806a-4601-9f5c-1656aa91ca24 https://www.aliexpress.com/item/3mm-Indoor-SMD0606-rgb-led-d... [2] https://twitter.com/ChuckMcManis/status/794023527720620032 https://twitter.com/ChuckMcManis/status/794023527720620032 [3] https://twitter.com/ChuckMcManis/status/794025248203022336 https://twitter.com/ChuckMcManis/status/794025248203022336 [4] https://1bitsquared.com/collections/embedded-hardware/products/1bitsy https://1bitsquared.com/collections/embedded-hardware/produc...
swerner 10y ago
Add some PWM for grayscale effects.
userbinator 10y ago
Now, I wonder if I can get an old calculator to play the accompanying 4 track MOD? Add some music and the demosceners at pouet.net might get interested in seeing it; they have a "wild" category for hardware/exotic demos like this. I agree with the second comment there about replacing the verbose chain of if-statements with a single expression; my first thought upon seeing that was "this really needs to be simplified"; likewise, the second part with 7 nearly identical lines shifting left and then right by the same amount, then multiplying by 255(?!) can be simplified to a loop; the way it looked with lines for B and C having a slightly-different mask constant is misleading, since it looks like a copy-paste error. Here's an (untested) attempt at simplifying the code: int yoffs[] = { 0, 1, 3, 4, 3, 1, 2 }; shift = 6 - ((digit&3) << 1); for(segs=0,i=0;i<7;i++) segs |= !!(screen_buffer[bx+yoffs[i]][bx] & 1 << shift+(i<1||i>2) ) << 6-i;
- SyneRyder 10y ago
  > they have a "wild" category for hardware/exotic demos like this. Revision 2017 has a Wild competition coming up in mid-April as well: https://2017.revision-party.net/compos/other https://2017.revision-party.net/compos/other
- waveydavey 10y ago
  Trying to understand his code. It looks like B and C's mask constants are correct. Look at the pixel map, B and C are the only segments with a pixel offset. His 'bittest' is a cast to bool!? anything not 0 becomes 255 to mask against the seg bit? Strange. Surely there's a case with something like this to unroll loops to simplify
Renaud 10y ago
There was an art project done a few years ago using 7-segment displays and animations, looked quite cool too: http://hackaday.com/2013/11/21/7-segment-display-matrix-visualizes-more-than-numbers/ http://hackaday.com/2013/11/21/7-segment-display-matrix-visu...
pdkl95 10y ago
> Notice there’s a lot of pixels here that don’t map to any segments, 30% that will never be displayed. Unfortunately this problem, the slant (italic) added by the hardware, and the bias introduced from mapping the horizontal lines (A, G) to the "left" pixels only, causes artifacts in the output. A good example is the left side of this[1] image, where the bottom of the 7-seg displaying "F" has a large jump rightward to the "1" below it. To get around these problems, aalib[2] renders each glyph that it will use, and for each block of pixels to display calculates nearest glyph. This automatically provides anti-aliasing for any shape glyph. As you already have the error (remaining distance to nearest glyph) for each group of pixels, it is also easy to add dithering to distribute the error across the image. [1] http://i1.wp.com/www.plingboot.com/wp-content/uploads/2017/02/cubez.jpg http://i1.wp.com/www.plingboot.com/wp-content/uploads/2017/0... [2] http://aa-project.sourceforge.net/aalib/ http://aa-project.sourceforge.net/aalib/
gaius 10y ago
From the name plingboot I detect an old-skool BBC Micro fan :-)

141 points by fourspace 10y ago

lukas 10y ago

This is awesome. Thanks for sharing.

jackhammons 10y ago

Very pretty. Nice effect!

ajnin 10y ago

It's amusing but a bit underwhelming, he's simply mapping a grid of pixels to segments, he's not taking the shape and orientation of the segments into account at all.

dang 10y ago
This style of comment isn't very good here because it comes across as putting down someone else's work. Some of that is just cultural and linguistic convention, of course, but on HN it's important; we know from long experience how it affects the community. It would be easy to rework this into a good comment by expressing your point additively rather than as fault-finding. For example, mention "shape and orientation of the segments" as the next thing to take into account and add some information about how one might do that. Then you're helping all of us learn.
vegabook 10y ago
Actually I think the nonlinear and binary mapping is what gives this quite an artistic effect. Reminded me of the predator self destruct countdown.

i336_ 10y ago

This is ever so slightly thread-hijacking but I've been wondering something slightly related for a while now: what's the downright cheapest way to get into really really big LED matrixes? Like the kind used for signs (of various sizes; let's say I'm referring to around <2ft sq). The major issue I'm completely ignorant of is how to get enough I/O that can drive the LEDs directly - I'm assuming something with lots of direct drive I/O and no intermediary components would be the cheapest way to do it (?). I understand multiplexing is the only way to survive at scale, but for small displays (say, 5x30 (= 150 LEDs)), what solutions would have enough I/O to drive each LED emitter individually, without scanning? I've always wondered what a truly flickerless LED matrix would look like. * (* Several years ago I had an odd incident where after using a scientific calculator I'd see weird swirling patterns overlaid on top of whatever I was looking at. The LCD itself was not faulty or damaged, and I couldn't see any flickering at all. Considering LCDs run at 30-100Hz, the whole incident (it stopped after a while, I have some theories as to why) made me curious what a truly DC-driven LED matrix would look like.)

bombela 10y ago
Some LEDs have an integrated chip, making it easy to daisy chain them as a big shift register. Example: https://www.adafruit.com/product/2343 https://www.adafruit.com/product/2343 You can find many similar type of LED in strips, trough holes etc. Some are faster than others. Addressable strips can be used to make big displays it seems: http://hackaday.com/2013/02/25/building-huge-displays-with-led-strips/ http://hackaday.com/2013/02/25/building-huge-displays-with-l...
ChuckMcM 10y ago
As it turns out this is getting pretty easy. A de-facto standard has emerged for these[1] LED modules, both in interfacing and in mounting. I used a couple in a LED clock[2] which can also tell time in QR Code[3] :-). Basically at $25 each you're looking at $3,750 in modules for a 640 x 480 display that in the "P3" (3mm dot pitch) size would be 1.92M wide (75.6") by 1.44M tall (56.7"). All of the LED driving is taken care of by the module, except for multiplexing the 'lines'. So these work by having drivers for one 'line' or LEDs (or 2 lines on the 32 LED high modules). You shift out the bits to them on a 16 pin plug. My clock as using an STM32F4 chip on a 1Bitsy[4] and was doing 240 FPS. Since these micros can be easily paralleled and synchronized you can drive an arbitrarily large sign by adding about $25 per 16 panels. Feeding them all data is a bit more complicated but not terribly so. [1] https://www.aliexpress.com/item/3mm-Indoor-SMD0606-rgb-led-display-module-192mm-x-96mm-64-32-pixle-Video-images-picture/1641364020.html?ws_ab_test=searchweb0_0,searchweb201602_3_10065_10000073_10068_10501_10000077_10000074_10503_10000032_119_10000030_10000026_10000023_431_10000069_10000068_10060_10062_10056_10055_10000062_10054_10000063_10059_10099_10000020_10000013_10103_10102_10000016_10096_10000056_10000059_10052_10053_10107_10050_10051_10106_10000097_10000094_10000091_10000007_10000050_10084_10000101_10083_10000100_10080_10000047_10000104_10082_10081_10110_10111_10112_10113_10114_10000089_10000086_10000083_10000041_10000044_10000080_10078_10079_10000038_10073_10000035_10070_10122_10123_10121_10126_10124-10503_10501,searchweb201603_2,afswitch_3,ppcSwitch_1,single_sort_1_default&btsid=0207e271-5f2c-489f-be15-a3aced211e7a&algo_expid=0eab590f-806a-4601-9f5c-1656aa91ca24-0&algo_pvid=0eab590f-806a-4601-9f5c-1656aa91ca24 https://www.aliexpress.com/item/3mm-Indoor-SMD0606-rgb-led-d... [2] https://twitter.com/ChuckMcManis/status/794023527720620032 https://twitter.com/ChuckMcManis/status/794023527720620032 [3] https://twitter.com/ChuckMcManis/status/794025248203022336 https://twitter.com/ChuckMcManis/status/794025248203022336 [4] https://1bitsquared.com/collections/embedded-hardware/products/1bitsy https://1bitsquared.com/collections/embedded-hardware/produc...

swerner 10y ago

Add some PWM for grayscale effects.

userbinator 10y ago

Now, I wonder if I can get an old calculator to play the accompanying 4 track MOD? Add some music and the demosceners at pouet.net might get interested in seeing it; they have a "wild" category for hardware/exotic demos like this. I agree with the second comment there about replacing the verbose chain of if-statements with a single expression; my first thought upon seeing that was "this really needs to be simplified"; likewise, the second part with 7 nearly identical lines shifting left and then right by the same amount, then multiplying by 255(?!) can be simplified to a loop; the way it looked with lines for B and C having a slightly-different mask constant is misleading, since it looks like a copy-paste error. Here's an (untested) attempt at simplifying the code: int yoffs[] = { 0, 1, 3, 4, 3, 1, 2 }; shift = 6 - ((digit&3) << 1); for(segs=0,i=0;i<7;i++) segs |= !!(screen_buffer[bx+yoffs[i]][bx] & 1 << shift+(i<1||i>2) ) << 6-i;

SyneRyder 10y ago
> they have a "wild" category for hardware/exotic demos like this. Revision 2017 has a Wild competition coming up in mid-April as well: https://2017.revision-party.net/compos/other https://2017.revision-party.net/compos/other
waveydavey 10y ago
Trying to understand his code. It looks like B and C's mask constants are correct. Look at the pixel map, B and C are the only segments with a pixel offset. His 'bittest' is a cast to bool!? anything not 0 becomes 255 to mask against the seg bit? Strange. Surely there's a case with something like this to unroll loops to simplify

Renaud 10y ago

There was an art project done a few years ago using 7-segment displays and animations, looked quite cool too: http://hackaday.com/2013/11/21/7-segment-display-matrix-visualizes-more-than-numbers/ http://hackaday.com/2013/11/21/7-segment-display-matrix-visu...

pdkl95 10y ago

> Notice there’s a lot of pixels here that don’t map to any segments, 30% that will never be displayed. Unfortunately this problem, the slant (italic) added by the hardware, and the bias introduced from mapping the horizontal lines (A, G) to the "left" pixels only, causes artifacts in the output. A good example is the left side of this[1] image, where the bottom of the 7-seg displaying "F" has a large jump rightward to the "1" below it. To get around these problems, aalib[2] renders each glyph that it will use, and for each block of pixels to display calculates nearest glyph. This automatically provides anti-aliasing for any shape glyph. As you already have the error (remaining distance to nearest glyph) for each group of pixels, it is also easy to add dithering to distribute the error across the image. [1] http://i1.wp.com/www.plingboot.com/wp-content/uploads/2017/02/cubez.jpg http://i1.wp.com/www.plingboot.com/wp-content/uploads/2017/0... [2] http://aa-project.sourceforge.net/aalib/ http://aa-project.sourceforge.net/aalib/

gaius 10y ago

From the name plingboot I detect an old-skool BBC Micro fan :-)