I guess I have two related questions about bit-order conventions when addressing 7-segment displays from microcontrollers...

  1. Is there a convention for the bit order of the segments?
  2. Is there a convention for the order of the displays when >1 are connected?

I'm currently driving 7-segment displays (with decimal points) with a TLC5917 (8-bit shift register and constant-current LED driver) for each display. Its outputs are only labeled OUT0..OUT7 on its datasheet, and of course I can chain them in any order.

Obviously this works as long as my microcontroller code matches my wiring. But I assume that as I get more experienced I'll be using more libraries for things like this, so if there's a convention that most follow, I'd like to get in the habit of using it now.

  • \$\begingroup\$ Is there a convention for the order of the displays when >1 are connected? ... think about this what if I want to increase the number of digits in the future? \$\endgroup\$
    – jsotola
    May 6, 2023 at 17:52
  • \$\begingroup\$ Your question is more about software than hardware, I think. And so far as I'm aware, there's not a standard. For example, this Arduino library only supports three DP for 4 digits, but supports the colon found in some clock displays. (The colon shares the DP position in the middle for a clock and both can be activated.) That's a specialized type of display, admitted. But if serious you'd need to do a very comprehensive survey to gain some kind of answer for your question. I don't think there's a single industry or gov't standard here. \$\endgroup\$ May 6, 2023 at 20:17

1 Answer 1


Yes, I would say 0..6 are segments a..g and 7 is the d.p. (image from Wikipedia)

enter image description here

Less so for the order of displays, perhaps. I use 0 = RH, so 0 is always the least significant digit, which makes sense to me.


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