5 ms·

"Just use a high resolution display" doesn't seem like the corect remedy. Next cheapest would be a low resolution LCD display, (30x80) that has its own set of

by Rhapso 2y ago

"Just use a high resolution display" doesn't seem like the corect remedy. Next cheapest would be a low resolution LCD display, (30x80) that has its own set of issues. 7 segments at minimum provide for high visibility even if they fail at high readability. note: price doesn't have to be money, complexity is expensive Why isn't there a market for 14-segment displays or other simple alphanumeric displays? edit: Childen comments use the phrase "for a few more $" a lot and i think they miss the point that if that was acceptable and easy we wouldn't be talking about it.

maxwell 2y ago
There is: https://www.sparkfun.com/products/18566 https://www.sparkfun.com/products/18566
- Kon-Peki 2y ago
  That display is really hard to read. I would say that if you're going to use a 7-segment display, it would be helpful to add a "test/diagnostic" button that does a pattern in which all segments are lit up in a predictable order, does a TOP pattern in which only the top segments are lit (to allow for device orientation), and then goes back to displaying exactly what was on the display prior to pressing the button.
  - crote 2y ago
    > That display is really hard to read. Most of that is just due to a lack of contrast. Add a slightly-tinted window in front of it to reduce the contrast between unlit segment & background, and it becomes a lot easier to read.
    - Kon-Peki 2y ago
      Yes, that is most likely the cause.
wrs 2y ago
16-segment displays are another longtime standard configuration. https://en.wikipedia.org/wiki/Sixteen-segment_display https://en.wikipedia.org/wiki/Sixteen-segment_display
wongarsu 2y ago
The market is flooded with 128x64 1.3" or 0.96" OLED displays. You can pick them up for anywhere from $1-$5, probably less if you bulk order. Sure, they bring some complexity. Instead of just driving some pins you now need a display library and at least some bitmap font. But they provide a lot more fidelity, are vastly more readable, and fail in more obvious ways without needing periodic test patterns (the flashing 8's or snakes mentioned in the paper so you can detect failed segments) For larger displays the choice becomes more interesting between OLED, LED matrices or 16 segment displays, but for small devices like those shown in the paper cheap OLEDs make the choice easy
- andylynch 2y ago
  They are cheap enough now, that they are appearing on disposable vapes (?!)
- s800 2y ago
  They also wear out quite quickly.
- Rhapso 2y ago
  "display library" bold of you to assume i have enough memory to drive the thing.
  - duskwuff 2y ago
    The most common models of small OLED displays (SSD1306, etc) have a (write-only) framebuffer in the display controller, and can be written to incrementally. If you structure your visual interface with certain simple constraints in mind, you can update it without using any additional dynamic memory.
    - Rhapso 2y ago
      That would probably be 100x more complicated than the actual business logic on a small microcontroller and there are limits to program memory for the "streaming this string to the screen by constantly computing if a given pixel is on one at a time" algorithm. edit addendum; If it was using a 7-segment display, it is either really cheap or really simple "a graphical GUI on a screen" IS NOT A REASONABLE NEXT STEP. I think we have radically different expectations of a simple embedded system.
bityard 2y ago
Agreed. "Just use a pixel matrix display" sounds an awful lot like, "Just use an Arduino." There are plenty of places where a simple and small microcontroller paired with a 4-digit segment display is the cheapest, simplest, and most defensible design decision.
- Rhapso 2y ago
  It appears we live in a universe where embedded systems aren't assumed to be a mission critical device by default. I'm not going to bother using a microcontroller to solve a problem if isn't a use case where the solution needs to be as simple and robust as possible.
TN1ck 2y ago
Some subways have 111 segmented displays, I really like them, the refresh rate is stunning. Here is a page selling them [0] and here is how they look [1], [2]. [0] http://www.reitberger.de/English/Large%20displays/Alphanumeric_LCD_Display_TK/Alphanumeric_LCD_Display_1.htm http://www.reitberger.de/English/Large%20displays/Alphanumer... [1] https://www.reddit.com/r/whatisthisthing/comments/6zsezx/this_lcd_display_appears_in_subway_trains_in/ https://www.reddit.com/r/whatisthisthing/comments/6zsezx/thi... [2] https://www.reddit.com/r/whatisthisthing/comments/e19uaz/what_kind_of_display_is_this/ https://www.reddit.com/r/whatisthisthing/comments/e19uaz/wha...
- Rhapso 2y ago
  Boo, only rated for 22 years of nonstop use :P

by Rhapso 2y ago

maxwell 2y ago

There is: https://www.sparkfun.com/products/18566 https://www.sparkfun.com/products/18566

Kon-Peki 2y ago
That display is really hard to read. I would say that if you're going to use a 7-segment display, it would be helpful to add a "test/diagnostic" button that does a pattern in which all segments are lit up in a predictable order, does a TOP pattern in which only the top segments are lit (to allow for device orientation), and then goes back to displaying exactly what was on the display prior to pressing the button.
- crote 2y ago
  > That display is really hard to read. Most of that is just due to a lack of contrast. Add a slightly-tinted window in front of it to reduce the contrast between unlit segment & background, and it becomes a lot easier to read.
  - Kon-Peki 2y ago
    Yes, that is most likely the cause.

wrs 2y ago

16-segment displays are another longtime standard configuration. https://en.wikipedia.org/wiki/Sixteen-segment_display https://en.wikipedia.org/wiki/Sixteen-segment_display

wongarsu 2y ago

The market is flooded with 128x64 1.3" or 0.96" OLED displays. You can pick them up for anywhere from $1-$5, probably less if you bulk order. Sure, they bring some complexity. Instead of just driving some pins you now need a display library and at least some bitmap font. But they provide a lot more fidelity, are vastly more readable, and fail in more obvious ways without needing periodic test patterns (the flashing 8's or snakes mentioned in the paper so you can detect failed segments) For larger displays the choice becomes more interesting between OLED, LED matrices or 16 segment displays, but for small devices like those shown in the paper cheap OLEDs make the choice easy

andylynch 2y ago
They are cheap enough now, that they are appearing on disposable vapes (?!)
s800 2y ago
They also wear out quite quickly.
Rhapso 2y ago
"display library" bold of you to assume i have enough memory to drive the thing.
- duskwuff 2y ago
  The most common models of small OLED displays (SSD1306, etc) have a (write-only) framebuffer in the display controller, and can be written to incrementally. If you structure your visual interface with certain simple constraints in mind, you can update it without using any additional dynamic memory.
  - Rhapso 2y ago
    That would probably be 100x more complicated than the actual business logic on a small microcontroller and there are limits to program memory for the "streaming this string to the screen by constantly computing if a given pixel is on one at a time" algorithm. edit addendum; If it was using a 7-segment display, it is either really cheap or really simple "a graphical GUI on a screen" IS NOT A REASONABLE NEXT STEP. I think we have radically different expectations of a simple embedded system.

bityard 2y ago

Agreed. "Just use a pixel matrix display" sounds an awful lot like, "Just use an Arduino." There are plenty of places where a simple and small microcontroller paired with a 4-digit segment display is the cheapest, simplest, and most defensible design decision.

Rhapso 2y ago
It appears we live in a universe where embedded systems aren't assumed to be a mission critical device by default. I'm not going to bother using a microcontroller to solve a problem if isn't a use case where the solution needs to be as simple and robust as possible.

TN1ck 2y ago

Some subways have 111 segmented displays, I really like them, the refresh rate is stunning. Here is a page selling them [0] and here is how they look [1], [2]. [0] http://www.reitberger.de/English/Large%20displays/Alphanumeric_LCD_Display_TK/Alphanumeric_LCD_Display_1.htm http://www.reitberger.de/English/Large%20displays/Alphanumer... [1] https://www.reddit.com/r/whatisthisthing/comments/6zsezx/this_lcd_display_appears_in_subway_trains_in/ https://www.reddit.com/r/whatisthisthing/comments/6zsezx/thi... [2] https://www.reddit.com/r/whatisthisthing/comments/e19uaz/what_kind_of_display_is_this/ https://www.reddit.com/r/whatisthisthing/comments/e19uaz/wha...

Rhapso 2y ago
Boo, only rated for 22 years of nonstop use :P