thatdecade
New Hunter
In this thread, I will be diving into the 7 segment animations and uncovering additional hidden frames not seen in the movies. I will also be sharing my latest interpretation of the chest display’s sequence.
I have previously shared my own version of the chest display circuit on github and have been selling updated versions based on RafalFett's excellent analysis.
With the help of Coffee Bean Dean (fettfromhell) and Corvair_fett, I have developed a new method of figuring out the sequence that feels more accurate.
Existing chest displays have used these and other interpretations to build fan animation sequences. Building what we see in the movie and using microcontrollers to recreate the sequence has had good results, but no fan knows the true sequence. Even the sequence I am about to describe is just an interpretation.
With that disclaimer, let’s dive in!
Arranged as shown in the diagram below:
Each LED segment has a pin at the back of the display that powers the LED when it is lit. Each digit also has a common pin that powers the entire display.
Typically, to drive a 5-digit 7-segment display, one wire is needed for each LED. That would be 5 x 7= 45 wires connected to the microcontroller. However, we can reduce the number of wires needed by multiplexing the LEDs, using the display’s common pin. By blinking the displays on and off one at a time, very fast, we only need 5 + 7 = 12 wires.
However, the original chest display circuit likely wasn’t wired this way. My hypothesis is that the prop maker used only 7 wires to achieve the variety of frames seen in the movies.
The black segments indicate parts of the display that are obscured in the screencaps and cannot be used for our analysis.
If we wire up our 5-segment displays in parallel to a single counter chip, so each display receives the same number, we can increment from 0 to 9 and repeat. Again, count the number of segments lit on each digit.
Comparing the results to the known frames from the screencaps, we can see similarities in the counts of lit segments.
If we imagine that we have a single digit counter chip driving all 5 displays in parallel again, but the wiring is jumbled between each digit, each digit will receive a unique wiring encoding of the number to be displayed.
Said a different way, instead of each digit receiving it’s normal abcdefg -> abcdefg wiring. We find the following:
With this new wiring, the number sequence will look similar to the known frames from the screencaps, minus the unknowns, and we can extrapolate additional frames that do not appear in the movies.
Here is the abcdefg encoding for each number (left), and it’s jumbled version per our encoding (right).
He developed the encoding through extensive work on paper, puzzling out the segment combinations. It was similar to solving non-base 10 sudoku puzzles, as each segment could only be used once in each number encoding and its wiring was then locked in for the other solutions.
This is not the only solution, so feel free to use this technique to submit your own sequence to this thread
I have previously shared my own version of the chest display circuit on github and have been selling updated versions based on RafalFett's excellent analysis.
With the help of Coffee Bean Dean (fettfromhell) and Corvair_fett, I have developed a new method of figuring out the sequence that feels more accurate.
Terminology:
- Segments: Each individual LED on the display.
- Character: Each grouping of 7 segments, makes a character. Commonly called a 7 segment display.
- Bars: Rectangular segments making up the bar graph.
- Frame: A still image comprised of a specific arrangement of lit segments on the display.
- Timing: The interval of time between frame changes in an animation sequence.
- Sequence: The order of frames in an animation.
- Animation Sequence: The combination of frames, sequence, and timing to create a moving display on the chest circuit.
Background Research
From watching the movie and taking screencaps, forum members have agreed on several frames and a few of the timings for the chest display characters. However, we do not have a complete understanding of the animation sequence for the chest display due to several issues with these screencaps:- The display is partially obscured by the way it is mounted in the chest armor.
- Poor angles and glare make it difficult to see the entire display.
- The film is edited, so any display sequences observed in different shots cannot be trusted.
- No film shot is long enough to see more than a few frames of the sequence at a time.
Existing chest displays have used these and other interpretations to build fan animation sequences. Building what we see in the movie and using microcontrollers to recreate the sequence has had good results, but no fan knows the true sequence. Even the sequence I am about to describe is just an interpretation.
With that disclaimer, let’s dive in!
Understanding 7 segment displays
7-segment displays have 7 segments. Labeled a, b, c, d, e, f, g.Arranged as shown in the diagram below:
Each LED segment has a pin at the back of the display that powers the LED when it is lit. Each digit also has a common pin that powers the entire display.
Typically, to drive a 5-digit 7-segment display, one wire is needed for each LED. That would be 5 x 7= 45 wires connected to the microcontroller. However, we can reduce the number of wires needed by multiplexing the LEDs, using the display’s common pin. By blinking the displays on and off one at a time, very fast, we only need 5 + 7 = 12 wires.
However, the original chest display circuit likely wasn’t wired this way. My hypothesis is that the prop maker used only 7 wires to achieve the variety of frames seen in the movies.
How??
To understand how this was possible, we need to take a closer look at some of our known frames from the screencaps. If we count the number of segments lit on each digit, we will notice that each digit has the SAME NUMBER of segments lit.The black segments indicate parts of the display that are obscured in the screencaps and cannot be used for our analysis.
If we wire up our 5-segment displays in parallel to a single counter chip, so each display receives the same number, we can increment from 0 to 9 and repeat. Again, count the number of segments lit on each digit.
Comparing the results to the known frames from the screencaps, we can see similarities in the counts of lit segments.
If we imagine that we have a single digit counter chip driving all 5 displays in parallel again, but the wiring is jumbled between each digit, each digit will receive a unique wiring encoding of the number to be displayed.
Said a different way, instead of each digit receiving it’s normal abcdefg -> abcdefg wiring. We find the following:
Code:
abcdefg abcdefg abcdefg abcdefg abcdefg
||||||| ||||||| ||||||| ||||||| |||||||
cbgefad dcfeagb edagbcf afebcdg bagfedcWith this new wiring, the number sequence will look similar to the known frames from the screencaps, minus the unknowns, and we can extrapolate additional frames that do not appear in the movies.
Here is the abcdefg encoding for each number (left), and it’s jumbled version per our encoding (right).
WTF? How did you come up with that cbgefad, whatever, encoding?
I commissioned Corvair_fett to find the encoding. I confirmed it matched my test screencaps, ignoring the obscured segments.He developed the encoding through extensive work on paper, puzzling out the segment combinations. It was similar to solving non-base 10 sudoku puzzles, as each segment could only be used once in each number encoding and its wiring was then locked in for the other solutions.
This is not the only solution, so feel free to use this technique to submit your own sequence to this thread
Next Steps
I plan to go deeper into the implementation of this circuit. Building the chest display with period-accurate chips. Including the asynchronous bargraph!
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