vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

HW to control 60 leds separately

Mon Jul 22, 2019 8:36 am

Hello,

I am noob in raspberry pi and I am analyzing the possibility to control about 60 Leds separately.
I have found docs related with this and I have seen several options that, indeed, I am not sure any of them are valid.
I would like to detail the solution that may be more accurate and I would appreciate any advice in any of my large list of doubts. Thanks in advance.

1- Expansion Hats based on MCP23017 through I2C
a) Feeding Leds directly
a.1 32 I/O
https://thepihut.com/products/modmypi-m ... ansion-hat
https://www.abelectronics.co.uk/p/54/io-pi-plus
https://www.robotshop.com/en/32-channel ... ry-pi.html
Questions:
How many Watts could be provided by output? I guess the HAT are feeding independently and should be no problem in 1W per output (32 W total). ¿Someone has tried any of this HATs and know if this is possible?

a.2 16 I/O
https://www.diymore.cc/products/i2c-iic ... der-module
https://learn.adafruit.com/gpio-expande ... t/overview
Questions:
How are they connected? Serial Ribbon similar to this picture?
https://raw.githubusercontent.com/souli ... Ribbon.JPG

b. Relays
b.1 With 16 relays
https://www.tme.eu/es/details/oky3016/m ... e/okystar/
Questions:
I haven’t seen I2C specification. I haven’t seen any post where someone is using it. ¿someone has work with it? ¿Someone knows how to connect them?

b.2 With 8 Relays
http://linuxgizmos.com/stackable-raspbe ... aximum-io/
I guess 8 of them is so much to put all together one hat into other. ¿some one knows any option to interconnect them?
2- Drivers for Leds (MAX6969)
I have seen in several forum that should be used Leds drivers or resistors to feed LEDs. I have understood this micro could help but I don’t find any HAT with this micro or other solution to drive the LEDs feeding.
Have I misunderstood something? Is necessary this Led driver or a resistor should be better/enough ?

3- SUPER BRIGHT LED
a. With HAT limited power, if so
https://www.adafruit.com/product/754
b. If 1 watt per output is available
http://www.produktinfo.conrad.com/daten ... _NMN00.pdf

c. Leds Strips. Cool but not an option, should be independent.

4- Auxiliary Elements
a. Perma-Proto Board
Something fast and easy to mount without PCBs?, something better?
https://www.adafruit.com/product/591

b. Wiring LEDS
I was thinking in FTP (like UTP but flexible). Each can handle 7 leds/ not bad and cheap. With heat-shrink tube ¿Any better solution for an easy mounting?

Sorry for this long post. I would appreciate any help in the HW guidance.

PiGraham
Posts: 3568
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: HW to control 60 leds separately

Mon Jul 22, 2019 9:23 am

I think the simplest option by far for 60 LEDs that are not tightly grouped is "neopixels" or "dotstars"

Serial addressable LED drivers that only require one or two GPIO lines to control lots of RGB LEDs independently.
You can get them on adhesive strips or wired chains (like Christmas lights) or on PCB matrix or discrete PCBs you can wire as you like.
strings or strips can be extended of you need more that ~50 LEDs on a chain and you can use multiple chains each on a gpio pin.

e.g.
https://www.amazon.co.uk/WS2811-Pixels- ... B00MXW054Y

https://www.youtube.com/watch?v=TFsn3GAdCHk

https://www.youtube.com/watch?v=D_QBlFIQk-o

https://www.youtube.com/watch?v=1r_wxBg0VMM

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Mon Jul 22, 2019 9:32 am

Thanks a lot. Yes.This is much better. I had found strips but no this option with independent leds. And it simplifies a lot the work. Thanks again.

PiGraham
Posts: 3568
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: HW to control 60 leds separately

Mon Jul 22, 2019 10:14 am

Some configurations might make more sense wired as a matrix. Such as LED cubes.
http://ozzmaker.com/raspberry-pi-contro ... be-python/

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Mon Jul 22, 2019 10:46 am

Thanks. I had seen this option. Allthough Cube is a great projec, it is more complex than this project requires,

PiGraham
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Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: HW to control 60 leds separately

Mon Jul 22, 2019 11:01 am

I see you mentioned "if 1 watt per output is available" and relays
How bright do you need? That might limit your options.

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Mon Jul 22, 2019 11:27 am

You are right. I am looking for Addressable superbright leds.
This leds should be seen almost on a sunny day so it should be really bright. If i dont find any addresable superbrigh leds, i guess i have to go with reles or similar. i dont have experience with super bright leds so, i dont know if leds similar to https://www.adafruit.com/product/754 are enought or i need 1 watt led.

PhatFil
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Location: Oxford UK

Re: HW to control 60 leds separately

Mon Jul 22, 2019 11:40 am

do you need 60X 1 w leds? could perhaps a number of 3w or more powerful leds be controlled in tandem to suppliment the light output of neopixel leds,

if for example the cumulative output from 60 x neopixels is say 30w , if you staggered 10 x 3w leds within the neopixel sequence, ie after 3 x neopixels are on turn on the 1st 3w led, etc it means controlling 10x leds above and beyond the neopixel sequence but thats still within the pi's capacity without expanding i/o.

PiGraham
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Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: HW to control 60 leds separately

Mon Jul 22, 2019 12:17 pm

daylight visibility could mean different things to different people.


One reviewer of the LED strings on Amazon I linked to wrote this:
Used in a public LED display, handled bad weather without issue and clearly visible even in bright sunlight and the drivers respond to the WS2812 protocol without any tweaks.
Sn the listing claims "Outdoor advertising," as an application.

That may or may not work for you. I suggest they are cheap enough to buy a string of 50 and try them out.

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rpdom
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Location: Chelmsford, Essex, UK

Re: HW to control 60 leds separately

Mon Jul 22, 2019 2:39 pm

You should note that although you can control the individual brightness and colour of each LED on a neopixel or dotstar string, you can't just update one LED at a time. You need to send the data for the whole string. Usually this is done by keeping a copy of the current state of the string in any array and updating the whole lot when any changes are made. This can happen fast enough that you won't notice the update other than the values which have changed.

The driver libraries usually do all that for you.

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Tue Jul 23, 2019 6:36 am

PiGraham wrote:
Mon Jul 22, 2019 12:17 pm
I suggest they are cheap enough to buy a string of 50 and try them out.
Yes. You are right. This is the first step. Thanks.

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Tue Jul 23, 2019 6:42 am

PhatFil wrote:
Mon Jul 22, 2019 11:40 am
do you need 60X 1 w leds? could perhaps a number of 3w or more powerful leds be controlled in tandem to suppliment the light output of neopixel leds,

if for example the cumulative output from 60 x neopixels is say 30w , if you staggered 10 x 3w leds within the neopixel sequence, ie after 3 x neopixels are on turn on the 1st 3w led, etc it means controlling 10x leds above and beyond the neopixel sequence but thats still within the pi's capacity without expanding i/o.
I guess, if i have to use supplementary Leds is better to use them as the final solution. Something i didnt say about the project is that i need string leds because one led maybe is about 1 meter far from the others and about 1,5m far from controler. I want to put each led in fixed points . one of them will light in its own spot.

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Tue Jul 23, 2019 6:44 am

rpdom wrote:
Mon Jul 22, 2019 2:39 pm
You should note ... have changed.
The driver libraries usually do all that for you.
Thanks. i didnt know it.

PiGraham
Posts: 3568
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: HW to control 60 leds separately

Tue Jul 23, 2019 10:49 am

If you do need to drive high power LEDs you could use the separate chip ws2811 and use that to control higher current switches.

Or you can use a higher supply voltage and put LEDs in series.

https://hackaday.io/project/8308-ws2811 ... ac/details

vmroa
Posts: 10
Joined: Thu Jul 18, 2019 7:03 am

Re: HW to control 60 leds separately

Mon Jul 29, 2019 8:12 am

Thanks but this solution requieres a more complex solution than i expected (PCB design, many ws2811 to work with...) i was looking for a easy way to control it, with i2c o SPI HATS or contrl devices already donel.

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