Add some PWM for grayscale effects.
Oldskool Demo on a 7 Segment Display
11–20 of 27 posts
Re: Oldskool Demo on a 7 Segment Display
#12There 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-visu...
Re: Oldskool Demo on a 7 Segment Display
#13This 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 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 driv…
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…
_Wow_, that is truly impressive. $3.7k for a ~2x1.5m² RGB (!!) display - and no added costs (besides a like Hmm. I wonder what the weatherproofing (particularly heatproofing) on these things is like. I know of a time/temp display high up on a building (probably around 1x1.2m²) that is constantly corrupted, I'm wondering if it's the 40°C days around here (Sydney Australia) that keep hitting it...
It's fascinating watching how QR encoding shifts and changes data - some of the time updates just adjust a few pixels, some of them adjust the whole barcode. I wonder what the source data for each frame was (but not terribly so).
So... if I understand right, these are line-buffered? You send it a line's worth of data, hit "go", and it redraws that line? 240FPS is good, wow.
One question: in the first couple of "ticks" of the second hand on the first clock video, I noticed how there appears to be a minor bit of "LED bleed" where some of the LEDs don't switch off for a couple fractions of a second. Curious, I had a look at the video frames: http://imgur.com/a/EVYB2. Is this an intrinsic problem in the driver system or perhaps a camera or encoding/compression glitch?
Re: Oldskool Demo on a 7 Segment Display
#14Now, 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"…
> they have a "wild" category for hardware/exotic demos like this.
Revision 2017 has a Wild competition coming up in mid-April as well:
Re: Oldskool Demo on a 7 Segment Display
#15Earlier quoted context omitted.
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…
_Wow_, that is truly impressive. $3.7k for a ~2x1.5m² RGB (!!) display - and no added costs (besides a like Hmm. I wonder what the weatherproofing (particularly heatproofing) on these things is like. I know of a time/temp display high up on a building (probably around 1x1.2m²) that is constantly corrupted, I'm wondering if it's the 40°C days around here (Sydney Australia) that keep hitting it... It's fascinating watc…
You can get an 80 inch TV for the same cost and roughly the same dimensions.
I am curious to understand what this can offer that a TV can't
Re: Oldskool Demo on a 7 Segment Display
#16Earlier quoted context omitted.
_Wow_, that is truly impressive. $3.7k for a ~2x1.5m² RGB (!!) display - and no added costs (besides a like Hmm. I wonder what the weatherproofing (particularly heatproofing) on these things is like. I know of a time/temp display high up on a building (probably around 1x1.2m²) that is constantly corrupted, I'm wondering if it's the 40°C days around here (Sydney Australia) that keep hitting it... It's fascinating watc…
You can get an 80 inch TV for the same cost and roughly the same dimensions. I am curious to understand what this can offer that a TV can't
1) a LED "wall" is far brighter than a comparably sized TV, that's important when you place stuff high on a building
2) An ordinary TV is designed to be looked at from the front, a slight angle skews the colors and if it's extreme enough the screen gets totally unreadable.
3) A TV eats up tons of power, a LED wall not so much.
Re: Oldskool Demo on a 7 Segment Display
#17> 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/2017/0...
Re: Oldskool Demo on a 7 Segment Display
#18From the name plingboot I detect an old-skool BBC Micro fan :-)
Re: Oldskool Demo on a 7 Segment Display
#19Earlier quoted context omitted.
You can get an 80 inch TV for the same cost and roughly the same dimensions. I am curious to understand what this can offer that a TV can't
1) a LED "wall" is far brighter than a comparably sized TV, that's important when you place stuff high on a building 2) An ordinary TV is designed to be looked at from the front, a slight angle skews the colors and if it's extreme enough the screen gets totally unreadable. 3) A TV eats up tons of power, a LED wall not so much.
Regarding point 3: At 150 modules consuming about 25W each, your LED wall is consuming about 3750W max. An 80" TV will consume about 300W.
Power consumption of the LED wall will, however, be highly dependent on the displayed content. A white screen will consume most, a black screen basically nothing, but displaying only dark images is not exactly what LED walls are usually used for.
The equation is simple: The brighter, the more power you'll need, and an LED wall is, as you say, far brighter.
Re: Oldskool Demo on a 7 Segment Display
#20Earlier quoted context omitted.
_Wow_, that is truly impressive. $3.7k for a ~2x1.5m² RGB (!!) display - and no added costs (besides a like Hmm. I wonder what the weatherproofing (particularly heatproofing) on these things is like. I know of a time/temp display high up on a building (probably around 1x1.2m²) that is constantly corrupted, I'm wondering if it's the 40°C days around here (Sydney Australia) that keep hitting it... It's fascinating watc…
You can get an 80 inch TV for the same cost and roughly the same dimensions. I am curious to understand what this can offer that a TV can't
Referencing the parent's comment, this lets you replace subpanels or even individual (sub)pixels as needed --- with a TV, if the panel is damaged, it's all or nothing.
I wonder what the weatherproofing (particularly heatproofing) on these things is like.
LEDs are more sensitive to heat than CRTs or incandescent lamps, but less than LCDs.