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Topic: Long length of addressable LED's? (200ft) (Read 957 times) previous topic - next topic

Shanedm1

I'd need to control all the LED's for sure. I'm programming patterns and gradual fading of all the LED's so it will be "kinetic". I have a decent understanding of FastLED and programming. But yes, all the LED's would need to be addressable. They will be diffused by shining up onto a ceiling of a large room.

PaulRB

Ok.... You seem to be avoiding my question. I'll assume you don't yet know the answer. It's ok to say that you don't know.

To help you make the decision, at 30 LEDs per metre, an ordinary Nano or Pro Mini will have enough ram memory. At 60 leds per metre, they won't.

You see, each controllable pixel (6 LEDs in the case of 24V strips) needs 3 bytes of ram to hold its colour/brightness before it is transmitted to the strip. Uno, Nano, Pro Mini only have 2000 bytes. Mega has more, but Mega is bulky and it would be a waste to use only 1 out of all those pins.

Other types of Arduino that are compact but have lots of ram are almost all 3.3V.  So a level shifter would be required to boost the 3.3V data signal up to the 5V level needed by the strip.

Shanedm1

I'll defintiely need the 60 LED's / meter for the accuracy and effect I'm looking for.
A HUGE thank you for the suggestions and advice !!!

PaulRB

#18
Aug 03, 2019, 07:42 pm Last Edit: Aug 03, 2019, 07:43 pm by PaulRB
One very new type of Arduino that is 5V but has more ram is the "Nano Every".

AdaFruit ItsyBitsy M0 is another option. It is 3.3V but has one special 5V pin for driving strips (i.e. it has a built-in level shifter on that pin.

PaulRB

I'll defintiely need the 60 LED's / meter for the accuracy and effect I'm looking for.
Accuracy? You said the light would be diffused on to a ceiling, so it's not going to be accurate. The main reason for needing 60 over 30 per metre would be simply to get more light, I would think.

CrossRoads

I offer Atmega1284P based boards that are IDE supportable and have 16K of SRAM.
Here is one example

Other form factors are available as well.
http://www.crossroadsfencing.com/BobuinoRev17
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

david_2018

One very new type of Arduino that is 5V but has more ram is the "Nano Every".
Unfortunately the Nano Every will not work with FastLED yet, that will require someone to do some significant modifications to the library.  It will work with Adafruit NeoPixel.  

Besides the extra RAM (6k), there is also a bit more program memory (48k), and the program memory and ram are in the same address space, so no special PROGMEM instructions are needed, the compiler will store as much as it can in program memory automatically.

Other types of Arduino that are compact but have lots of ram are almost all 3.3V.  So a level shifter would be required to boost the 3.3V data signal up to the 5V level needed by the strip.
I have been running 5V led strips from 3.3V micros (ESP32) and never seen a problem with it.
If you do something for production I would recommend a level converter, but for hobby it might not be necessary. The difference is that if one combination fails, it is easy to replace the strip or processor when doing hobby, but when selling stuff for a lot of money it would be a bad excuse.
Adding a pullup resistor to 5V on the output will make the probabilities for success with 3.3V micro even greater (preferable on a 5V tolerant pin, but the protection will usual handle it).

PaulRB

#23
Aug 03, 2019, 08:46 pm Last Edit: Aug 03, 2019, 08:51 pm by PaulRB
Quote
I have been running 5V led strips from 3.3V micros (ESP32) and never seen a problem with it.
But the OP will be using 24V strips!

I also had no problems with running 5V strips with 3.3V micros for a long time. Then I found some 5V strips which I could not control reliably unless I used a level shifter. Later I found 12V strips which also needed a level converter. I've never used 24V strips, but I would not bet much of my own money that they would not need a level converter.

PaulRB

#24
Aug 03, 2019, 09:05 pm Last Edit: Aug 03, 2019, 09:11 pm by PaulRB
Unfortunately the Nano Every will not work with FastLED yet, that will require someone to do some significant modifications to the library.  It will work with Adafruit NeoPixel. 
Thanks David, well caught.

Besides the extra RAM (6k), there is also a bit more program memory (48k), and the program memory and ram are in the same address space, so no special PROGMEM instructions are needed, the compiler will store as much as it can in program memory automatically.
That's interesting, I did not pick that up from Arduino's marketing blurb. So they changed the cpu architecture from Havard to Von Neumann.

But the OP will be using 24V strips!

I also had no problems with running 5V strips with 3.3V micros for a long time. Then I found some 5V strips which I could not control reliably unless I used a level shifter. Later I found 12V strips which also needed a level converter. I've never used 24V strips, but I would not bet much of my own money that they would not need a level converter.
I would expect most strips to work with a 3.3V logic output, but as I wrote above I would not base a production in. As a level translator any HCT chip can be used. Like 74HCT14 or 74HCT244.

One very new type of Arduino that is 5V but has more ram is the "Nano Every".
Interesting micro controller, but way to expensive. I hope there will be much cheaper clones, I can easily use more FLASH and RAM.

Shanedm1

I was going to install about 200 ft on a coffered ceiling so the light would shine upwards on the ceiling along the perimeter. The intent isn't to sell anything but have it at least reliable.

The info you guys have is awesome!
Thank you !

As far as providing power along the length of the strip, would I just have some male/female plugs along the length? I see how each strip is connected with the waterproof connectors but what about the power?

PaulRB


david_2018

What types of effects do you intend to run on the LEDs?  The programming might get a bit complicated, but if you split the LEDs into two strips of 100ft each, and drive them off separate output pins, it is possible to have FastLED use a single buffer for both strips, which would only require half as much ram.

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