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enter image description hereI have a display as in photo I sent you. But it has no label so I can't get data sheet. It has seven pins only. How to know its pin configurations? Please help me.enter image description here

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marked as duplicate by pipe, Dave Tweed May 14 '18 at 10:23

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    \$\begingroup\$ Buy one with a data sheet... Failing that trial and error with a multimeter or a low voltage supply... What did you take it out of? Trace the original circuit... \$\endgroup\$ – Solar Mike May 14 '18 at 4:34
  • \$\begingroup\$ With just 7 pins it either has less segments than a 4 digit display if directly driven or it is driven by serial or BCD data. Any further information of the source of the part may help to determine connection details. A photo of the other side even may convince that it is a 4 digit display. \$\endgroup\$ – KalleMP May 14 '18 at 7:11
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    \$\begingroup\$ If you have a larger stock of the displays you could smash one open carefully to determine the construction and presence of driver circuits. The photo is also of troll quality so you are likely to be down voted from frustration alone. \$\endgroup\$ – KalleMP May 14 '18 at 7:13
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[This answer was written before the OP posted the front view of the display.]

A four-digit seven-segment display will normally have four multiplexed digits. This will require eleven pins and twelve if it has decimal points.

enter image description hereenter image description here

Figure 1. Common anode and common cathode 7-segment displays.

enter image description here

Figure 2. Each digit in a seven-segment display has eight pins for the segments and one for the common anode or cathode. (This circuit uses common cathode type.) Source: 7-segment display basics.

It seems very unlikely that you have a 4 x 7-segment display in your photo.

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    \$\begingroup\$ We know it has 4x7 segments (plus at least 7 more) because we can see the segments. \$\endgroup\$ – immibis May 14 '18 at 8:40
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    \$\begingroup\$ @immibis In all fairness, OP neglected to post the photo of the segments until after this answer was written. \$\endgroup\$ – pipe May 14 '18 at 8:55
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Your module is almost identical to the one in this question.

The accepted answer (here), posted by the person who asked the question, says that the segments are Charlieplexed (https://en.wikipedia.org/wiki/Charlieplexing).

@pipe counted 35 segments...

With 6 pins, up to 30 LEDs can be Charlieplexed - not enough.
With 7 pins, up to 42 LEDs can be Charlieplexed.

...so Charlieplexing seems most likely.

Unless you can find the datasheet, a bit of trial and error will yield how the segments are connected. Use a 5V supply and a resistor (say, 1K), and connect each pair of pins in turn (all pairs, all polarities), noting down which segment lights up.

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    \$\begingroup\$ Interesting find, it's identical enough to make it a duplicate! It's not "almost" identical, it is the same display. \$\endgroup\$ – pipe May 14 '18 at 9:49
  • \$\begingroup\$ You're right, it is the same as the other answer! Although in their question the first photo shows a variant (a decimal point between the right-two digits, and different surrounding segments: AM/PM instead of play/pause symbols, etc) - definitely a duplicate. \$\endgroup\$ – Matthew Butler May 14 '18 at 10:20

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