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A 7-segment display is a great way to display numbers using your Propeller. You can find these in many products that need to display numbers in a simple way, like clocks, kitchen appliances, or digital scales. This display uses seven LEDs arranged in a special pattern that makes it possible to show any number from 0 to 9. This tutorial will show you exactly how to control the display, and use it to count.

Each individual LED in the 7-segment display needs a resistor between it and the Propeller’s I/O pin. When each I/O pin is set to high (outputs 3.3 V), the LED it is connected to lights up. Any resistor value between 100 Ω and 1 kΩ will work for the LED resistor and the lower the resistance, the brighter the segment. It’s best to use resistors of the same value so all the segments light up evenly.

First, the code sets all the pins between 8 and 15 to outputs with set_directions(15, 8, 0b11111111). Next, the code outputs a 0 with the command set_outputs(15, 8, 0b11100111). If you look through the rest of the code, you can see that each digit has its own binary representation. The number 1, for example, is represented as 0b10000100. If you investigate more closely, you’ll notice the binary digits correspond to I/O pins, in reverse order, from 15 to 8. So the binary representation for the number 1 sets pins 15 and 10 to high. If you look at the schematic, you’ll notice that pin 15 is connected to segment B and pin 10 is connected to segment C. Referring to the diagram below, you’ll see that together, segments B and C make up the number 1.

7-segment LEDs can also be used to display letters. You may already have seen examples of this on CD/DVD players, calculators, or microwaves. Although every letter of the English alphabet can be represented (in capital and/or lowercase form) using a single device, some letters are a bit more difficult to display in an easily recognizable way.

The capital letter “A”, for example, is easy to display using 0b11110101 as one of your outputs’ binary representations in SimpleIDE (try it!). Alternatively, letters like “w” or “k” require a bit more imagination to represent using only a single 7-segment LED; often it takes LEDs with more segments or two, side-by-side devices to accurately display them.

Want to learn more? Visit the Wikipedia article about 7-segment display character representations at http://en.wikipedia.org/wiki/Seven-segment_display_character_representations.

Instead of referencing each number individually, a better method to display numbers on a 7-segment display is to store each binary value in an array and then reference them later in the code. Here, we use a for loop to do just that.

Since the Propeller Activity Board (original or WX version) has a built-in analog to digital converter, you can make a voltmeter using your 7-segment display. Try combining what you learned in Measure Volts with the information in this tutorial to make your display show voltages.

Tip: If you have two 7-segment displays, you can use the decimal point on the first display. This involves changing the 5th bit of every value for the first display: i.e. 0b11100111 becomes 0b11101111.

A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.

Seven-segment displays are widely used in digital clocks, electronic meters, basic calculators, and other electronic devices that display numerical information.

Some early seven-segment displays used incandescent filaments in an evacuated bulb; they are also known as numitrons.potted box. Minitrons are filament segment displays that are housed in DIP packages like modern LED segment displays. They may have up to 16 segments.

Many early (c. 1970s) LED seven-segment displays had each digit built on a single die. This made the digits very small. Some included magnifying lenses onto the design in an attempt to make the digits more legible.

The seven-segment pattern is sometimes used in posters or tags, where the user either applies color to pre-printed segments, or applies color through a seven-segment digit template, to compose figures such as product prices or telephone numbers.

For many applications, dot-matrix LCDs have largely superseded LED displays in general, though even in LCDs, seven-segment displays are common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography. In contrast, the shapes of LED segments tend to be simple rectangles, reflecting the fact that they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of 7-segment displays. However, the high recognition factor of seven-segment displays, and the comparatively high visual contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators.

The seven-segment display has inspired type designers to produce typefaces reminiscent of that display (but more legible), such as New Alphabet, "DB LCD Temp", "ION B", etc.

Using a restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrases using a technique known as "calculator spelling".

Seven-segment displays may use a liquid crystal display (LCD), a light-emitting diode (LED) for each segment, an electrochromic display, or other light-generating or controlling techniques such as cold cathode gas discharge (Panaplex), vacuum fluorescent (VFD), incandescent filaments (Numitron), and others. For gasoline price totems and other large signs, vane displays made up of electromagnetically flipped light-reflecting segments (or "vanes") are still commonly used. A precursor to the 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube. Starting in 1970, RCA sold a display device known as the Numitron that used incandescent filaments arranged into a seven-segment display.electroluminescent display.

In a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device.IC sockets. Integrated displays also exist, with single or multiple digits. Some of these integrated displays incorporate their own internal decoder, though most do not: each individual LED is brought out to a connecting pin as described.

Multiple-digit LED displays as used in pocket calculators and similar devices used multiplexed displays to reduce the number of I/O pins required to control the display. For example, all the anodes of the A segments of each digit position would be connected together and to a driver circuit pin, while the cathodes of all segments for each digit would be connected. To operate any particular segment of any digit, the controlling integrated circuit would turn on the cathode driver for the selected digit, and the anode drivers for the desired segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit display with seven segments and a decimal point would require only 8 cathode drivers and 8 anode drivers, instead of sixty-four drivers and IC pins.

The seven segments are arranged as a rectangle of two vertical segments on each side with one horizontal segment on the top, middle, and bottom. Often the rectangle is hexagons, though trapezoids and rectangles can also be used), though in the case of adding machines, the vertical segments are longer and more oddly shaped at the ends in an effort to further enhance readability. The seven elements of the display can be lit in different combinations to represent the Arabic numerals.

The segments are referred to by the letters A to G, where the optional decimal point (an "eighth segment", referred to as DP) is used for the display of non-integer numbers.gfedcba and abcdefg. In the gfedcba representation, a byte value of 0x06 would turn on segments "c" and "b", which would display a "1".

Alternate patterns: The numeral 1 may be represented with the left segments, the numerals 6 and 9 may be represented without a "tail", and the numeral 7 represented with a "tail":

In Unicode 13.0, 10 codepoints had been given for segmented digits 0–9 in the Symbols for Legacy Computing block, to replicate early computer fonts that included seven-segment versions of the digits.

Most letters of the Latin alphabet can be reasonably implemented using seven segments. Though not every letter is available, it is possible to create many useful words. By choosing better synonyms, it is possible to work around many shortcomings of seven-segment alphabet encodings. Some uppercase letters ("I", "O", "S", "Z") look identical to numerical digits ("1", "0", "5", "2"), though it is possible to use lower-case "o" and "i", or putting "I" on the left. Lowercase letters "b" and "q" are identical to the alternate numerical digits "6" and "9". Depending on the situation, some of these problem characters can be used when no numeric values are used in the same word/phrase, see examples below.

Short messages giving status information (e.g. "no dISC" on a CD player) are also commonly represented on 7-segment displays. In the case of such messages it is not necessary for every letter to be unambiguous, merely for the words as a whole to be readable.

There are enough patterns to show all the letters but few representations are unambiguous and intuitive at the same time.sixteen-segment and dot matrix displays are better choices than seven-segment displays.

Seven segments are capable of displaying some punctuation glyph characters. The hex value for each Unicode character is shown, of which the lower 8-bits of most of these exist as ASCII characters too.

There are also fourteen- and sixteen-segment displays (for full alphanumerics); however, these have mostly been replaced by dot matrix displays. Twenty-two-segment displays capable of displaying the full ASCII character set

"Application Note 3210 – Quick-Start: Driving 7-Segment Displays with the MAX6954" (PDF) (Application note) (3 ed.). Maxim Integrated. March 2008 [2004-06-25]. Archived (PDF) from the original on 2017-03-20. Retrieved 2013-05-06.

"DL-3422 4-digit 22-segment alphanumeric Intelligent Display preliminary data sheet". Internet Archive. Litronix 1982 Optoelectronics Catalog. p. 82. Retrieved 2016-09-03.

A 7-segment display is commonly used in electronic display devices for decimal numbers from 0 to 9 and in some cases, basic characters. The use of light-emitting diodes (LEDs) in seven-segment displays made it more popular, whereas of late liquid crystal displays (LCD) have also come into use.

A seven-segment display is made of seven different illuminating segments. These are arranged in a way to form numbers and characters by displaying different combinations of segments.

The binary information is displayed using these seven segments. LED is a P-N junction diode that emits energy in the form of light, different from a standard P-N junction diode which emits in the form of heat.

Whereas LCD uses liquid crystal properties for displaying and does not emit light directly. These LEDs or LCDs are used to display the required numeral or alphabet.

Seven-segment devices are generally made up of LEDs. These LEDs will glow when they are forward-biased. The intensity of the LEDs depends on the forward current.

So, a sufficient forward current has to be provided to these LEDs to glow with full intensity. This is provided by the driver and is applied to the seven segments.