what is the logic in displaying desired numbers in 7 segment 4 digit display. Ie, how to know the leg combinations to see the desired number in the display
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1\$\begingroup\$ Datasheet says? \$\endgroup\$Ignacio Vazquez-Abrams– Ignacio Vazquez-Abrams2014年10月21日 17:45:00 +00:00Commented Oct 21, 2014 at 17:45
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\$\begingroup\$ I don't know how to get its data sheet.it has 6 legs each on both sides and "822 WP4041ARB-3-7.5" writen over it.thats all i know \$\endgroup\$MacroBoy– MacroBoy2014年10月21日 17:59:12 +00:00Commented Oct 21, 2014 at 17:59
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\$\begingroup\$ wpelectronic.com/productstype/led-light-bar-display-.htm \$\endgroup\$Ignacio Vazquez-Abrams– Ignacio Vazquez-Abrams2014年10月21日 18:02:29 +00:00Commented Oct 21, 2014 at 18:02
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\$\begingroup\$ I couldn't find the data sheet. \$\endgroup\$MacroBoy– MacroBoy2014年10月22日 04:46:07 +00:00Commented Oct 22, 2014 at 4:46
1 Answer 1
Generally the segments are named a through g, starting with the top segment a, clockwise around to the top left segment f, and finally the center segment g. See the wikipedia article: https://en.wikipedia.org/wiki/Seven-segment_display . Unfortunately, I cannot post the image here because it is an SVG.
Consult the datasheet or poke around with a resistor and battery to work out which pins correspond to which segment. Generally displays are either common anode or common cathode, with all of the anodes or cathodes connected to one common pin. There are also some common pinouts, so if you don't know the part number, do a google image search to find a part number of a display that looks the same and then use that to find the datasheet.
With a 4 digit display, there will generally be four separate commons - one for each digit - and all of the corresponding segments will be wired in parallel. So if you put a current in the correct direction between the common for digit 1 and the segment a connection, segment a on digit 1 will light up. It is not possible to illuminate two digits with different patterns at the same time with this configuration. If you want different patterns on each digit, what you need to do is multiplex. Turn one digit on at a time, and cycle through them all at high speed.