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LED rings - 270 degrees or 360?


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Hello all! I have been away for a while, and looking forward to revisiting some of my projects this winter.


I had avoided making an MB64 type controller because I wanted to use encoders but felt intimidated by discrete wiring of LED rings. Now I am more confident, and might just make a PCB for this. 


What I am wondering is - why do all of the examples I see have the LEDs of the ring spaced with a similar approximate  270 degree rotation, like with an analog pot? My Bourns encoders (I bought for a SEQ3 ages ago) have continuous rotation, so it seemed obvious to me to have continuous indicators also, an equally-spaced circle. So I am wondering are there any aesthetic or functional reasons for the 270 degree arc? If I make them 360 instead would I need to change anything in the code?


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For code change it depends, if you need to draw a 270° scale within a 360° led ring, the answer is yes. If not, you don't need.
It's better to use a multiple of 8 for the number of leds that form your ring.

My opinion is that an Open Ring is better for layout routing first and a potentiometer travel is a symbol for me then maybe by convention...
Using a ring for a potentiometer In parallax mode(or not) is very interesting for feeling and playability.
300° pots are also common, with a 300° led ring you can draw a 270° travel too.
This angle lets the possibility to use most common pots and encoders.

I thought a lot about this subject during the OLRE16 design...
One more thing... I choose to remove one led from the ring. By this way there's an odd number of leds, by symmetry the middle led is automatically placed at 0 o'clock, better for bipolar travel ;).
The last one is used as an index(e.g. step position, on, mute, solo), and placed at 6 o'clock.


Edited by Antichambre
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And one little user-interface aspect, having a defined "start" and "end" can make things visually more intuitive, e.g. when you have a huge controller board with many LED-rings, it is easier to see, if a parameter is "close to the beginning" or the "end" of a range, if you have a "ring", that is not a full 360°. This comment does not apply, if you have a "progress-bar" ring, that "turns on" more LEDs (not just one) as the parameter value is increased.

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Thanks for the input! What I suspect will happen is that I will do all the hard, expensive work of drilling out an enclosure and wiring LEDs, only to want to re-do them once I am using the box. So I suppose I should try breadboarding something first to understand something of how it works.


Antichambre: That was another reason I was thinking about 360 degrees - it is easy to start from "compass point" orientation while keeping 16 LEDs.


Hawkeye: Is that how the MB code defaults to working, within a range? If so, does the indicator just stop at the end if the encoder rotates further? I guess that this makes more visual sense. If I advanced one LED per value, there would be no visual indication of what cycle I was on. Unless they changed color after 16 or something.


Thanks for the help!



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