LED Matrix Failure
- 57" x 30" Black Upholstery Fabric
- Metal Grommet Press
- Adafruit DotStar Digital LED Strip - Black 60 LED - Per Meter - BLACK
- Power Supply 5V@60A 350W
- Connectors - each set of Dotstar LED comes with a pair of 4-pin "male" and "female" connectors these were reused in the design
the base was made with some black upholstery fabric. a piece size of 57" x 30" was cut and taken to a seamstress to have the edges sewn. after sewing, a manual metal grommet press was used to add grommets to each of the four corners.
The Dotstar LEDs for the failed version were arranged in a chained sequence. the intention was to cut the strips and align them on the fabric in a "left to right - left to right" sequence similar to tradition LCD panels. this is also sometimes referred to as "Row Major" sequence. this sequence is typically something like this for an 5x5 pixel example:
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
the issue is that to implement this with the LED strips, two wires need to connect the end of one LED strip to the beginning of the next, in the 5x5 pixel example above, the SPI clock and data need to connect from the end at 05 to the beginning of the next line at 06. this creates a wiring nightmare on the back side of the design:
the thought was by design it this way, and working similar to existing display devices, software support would be easy and require little or no effort to implement. while this was true the long wires created both signaling and logistical problems during implementation.
To remove the need for the long wires it makes more sense hardware wise to implement the strips using the "left to right - right to left" sequence. this is sometimes referred to as "ZigZag" sequence. this is represented again in a 5x5 pixel example:
01 02 03 04 05 10 09 08 07 06 11 12 13 14 15 20 19 18 17 16 21 22 23 24 25
as you can see the encoding is a little more difficult, but it can be easily handled in software to sequence this. the trade off here between a little more difficult in software, and a LOT easier in hardware, really is the only choice.
- power connections
- long wires
- broken flex pads
- long SPI signals
- quick fix
- eagle files