OctoPi mods and lighting...

[Manatee Diver]

I hate Python. It seems as if somebody was trying to pick the worst of every preceding language when they crafted it ...

Too high of an emphasis on readability, is what I think the problem is.

 

[-JD-]

Too high of an emphasis on readability, is what I think the problem is.

Weak variable typing and the use of indentation as block delimiting are the first two things that pop to mind. Sooooo easy to break that code.

 

[The Ruttmeister]

Pete
0-255 is The DMX (DMX 512 1992) protocol. It's 8bit Our control input would be 0-10 (0 being 0 and 10 being 255) becuase originally way back DMX was controlled by a 0-10v signal
Generally you would have 4 channels , RGB and intensity ( rather than RGB + Intensity for each array)
On a lighting control desk we would give the item a start address and then have 3 other addresses assigned to it
Hue and Sat can be additional channels (depending on what the microprocessor looks for) or be done by manipulating each channel
The same basic protocol is in use today in professional lighting systems within the entertainment and TV world with each fixture looking for a 0-255 signal on each channel (up to 20 times per sec)

The neopixel's use their own protocol, yes its 8 bit, no its nothing like DMX (1992 or otherwise). DMX has never been anything to do with 0-10v systems. Those were replaced by AMX192 (which Stand Lighting agreed to publish and effectively kill as part of the industry wide adoption of DMX, which itself was based on CMX which was based on RS485). Neopixels can be individually addressed, but that address is based in their position in the chain, it is not configurable in the way DMX devices are.

I highly recommend the book 'The Speed of Light' which is probably out of print, but if a great insight into how the early days of computer controlled lighting shook out. I learnt where a bunch of the common terms in lighting desk programming came from thanks to that book.

Plus while DMX might still be in use, its all wrapped in streaming ACN last I heard

 

[The Chairman]

OK, I've have not solved the neopixel issue, so it's time to simplify. I still like the ring concept: it just looks cool. Since I can't find a bunch of warm white LEDs in a ring, I guess I have to make it. So, I bought 100 SMD LEDs for a bit under $7.00. The 100 ohm resistors are on their way with the cost being less than a buck. Yesterday and today I learned and played around with KiCAD, a PCB design tool. Wow. It's cool. This is my second attempt at the ring. The first was fine, but this one is far nicer looking.

Now, I'm headed to the HackerSpace to meet with Joe. He's going to teach me all about Gerber files. I'll send those to the PCB house, and if everything goes right, I'll have a number of these PCBs in my hand by Monday. Then I'll populate it with the surface mount LEDs and resistors, put them in the Surface Mount Device oven and solder these babies on. Then all that's left is the smoke test and figuring out a way to turn them on and off from afar. I do like the way I get to personalize this.

 

[The Ruttmeister]

I'm an Eagle user so I can't help with KiCAD.

But your board looks nice. 2 suggestions though. Firstly, there's no reason for the two ring traces to not be flooded (so they take up all the unused board). Secondly you should add mounting holes. Even if you don't end up using them its a nice thing to have, and really hard to add after the fact.

That and you should add a connector. I know some people might disagree, but its a pain in the arse if you damage the wires and end up having to resolder them. Plus it makes assembly easier.

 

[The Chairman]

Mounting holes are an interesting thought, though the mount is a press hit. Easy enough to add now, though.

This is my third design. The LEDs and resistors are perfectly placed (no eye balling) and I have full flood. Not as pretty, and I'go look to see about adding a couple of mounting holes.

 

[The Chairman]

For those who create PCBs, just who do you use to make them up? With 2/3 day shipping, I'm seeing $3/piece for 10 and about $2/piece for 20.

 

[The Ruttmeister]

By flood I meant have your +5V and GND traces each part of the flood, its not super important, but its kinda nice.

And I use either OSHpark or SeeedStudio. Although I'm normally ordering stuff in 2oz copper, so its more expensive and longer lead times. Seeed also have low cost PCBA if you don't want to deal with reflowing SMT parts.

And you connector looks like its on the same side as the LED's, that might get in the way. Consider moving it to the back and consider a 90 degree connector!

 

[The Chairman]

And you connector looks like its on the same side as the LED's, that might get in the way. Consider moving it to the back and consider a 90 degree connector!

The connector is a "place holder" as it were. I used it because they will send it as a PTH. There is a small cut out where two wires will exit through the rear.

 

[Oitzu]

Maybe place a mosfet directly on the pcb to control the LEDs?
Adds one more connection from the pi to the pcb but avoids additional parts for controling the lights.