HI All
I was prompted to investigate these - we like to illuminate the outside
(& inside!) of the house, and these looked like a good idea.
The one I purchased allegedly had two lasers (red & green) and four
different effects.
Trouble is - this one seems to be faulty - the ebay seller has refunded
my money (bless 'em).
The unit has a waterproof momentary push-button on the back, it seems to
need a press in order to start the thing working - which is kind of
inconvenient as our outdoor lights are usually on a timer, and, even if
this unit was working properly, I can't see me nipping outside every
night just to push the button!
Just wondering if anybody else has one of these new-fangled units - and
whether theirs starts automatically when mains is switched on, or if
it's a elfin-safety feature of the unit that it requires a digit on the
button to start the lasers?
The very thin user manual also says that the unit needs to be switched
'off' to cool down for 30 minutes after 5 hours of running... this
particular unit doesn't run for more than a minute or so before cutting
out, so it's kind of academic g
Any real-life experiences, please?
Thanks
Adrian

On Wed, 30 Nov 2016 18:00:09 +0000
Adrian Brentnall wrote:

HI All
I was prompted to investigate these - we like to illuminate the
outside (& inside!) of the house, and these looked like a good idea.
The one I purchased allegedly had two lasers (red & green) and four
different effects.
Trouble is - this one seems to be faulty - the ebay seller has
refunded my money (bless 'em).
The unit has a waterproof momentary push-button on the back, it seems
to need a press in order to start the thing working - which is kind
of inconvenient as our outdoor lights are usually on a timer, and,
even if this unit was working properly, I can't see me nipping
outside every night just to push the button!
Just wondering if anybody else has one of these new-fangled units -
and whether theirs starts automatically when mains is switched on, or
if it's a elfin-safety feature of the unit that it requires a digit
on the button to start the lasers?
The very thin user manual also says that the unit needs to be
switched 'off' to cool down for 30 minutes after 5 hours of
running... this particular unit doesn't run for more than a minute or
so before cutting out, so it's kind of academic g
Any real-life experiences, please?
Thanks
Adrian

I seem to remember a discussion hereabouts concerning the illegality of
the lasers in these or similar units. Maybe somebody who took part in
that thread might come along shortly.

--
Davey.

That sounds a bit naff. I wonder if there are any of the stage devices going
second hand. Even back in the 80s some of these seemed to be able to run all
the time with little issues out of dooors and in the rain, at least when I
could see back then raindrops and lasers made for a very interesting almost
strobe droplets slow motion effect.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Adrian Brentnall" wrote in message
...
HI All
I was prompted to investigate these - we like to illuminate the outside (&
inside!) of the house, and these looked like a good idea.
The one I purchased allegedly had two lasers (red & green) and four
different effects.
Trouble is - this one seems to be faulty - the ebay seller has refunded my
money (bless 'em).
The unit has a waterproof momentary push-button on the back, it seems to
need a press in order to start the thing working - which is kind of
inconvenient as our outdoor lights are usually on a timer, and, even if
this unit was working properly, I can't see me nipping outside every night
just to push the button!
Just wondering if anybody else has one of these new-fangled units - and
whether theirs starts automatically when mains is switched on, or if it's
a elfin-safety feature of the unit that it requires a digit on the button
to start the lasers?
The very thin user manual also says that the unit needs to be switched
'off' to cool down for 30 minutes after 5 hours of running... this
particular unit doesn't run for more than a minute or so before cutting
out, so it's kind of academic g
Any real-life experiences, please?
Thanks
Adrian

On 01/12/2016 08:43, Brian Gaff wrote:
That sounds a bit naff. I wonder if there are any of the stage devices going
second hand. Even back in the 80s some of these seemed to be able to run all
the time with little issues out of dooors and in the rain, at least when I
could see back then raindrops and lasers made for a very interesting almost
strobe droplets slow motion effect.
Brian

HI Brian
Yes - something's not right somewhere g
After sitting in my (cold) outdoors workshop overnight, the laser
decided that it would work... but only for about 5 minutes.. then it
stopped!
Could be the power-supply overheating, I guess - toying with the idea of
feeding it 5v from a.n.other psu - but not sure I can really be bothered g
As I say - the seller refunded me in full, so the device owes me
nothing, - but that little 'engineer' voice keeps saying "perhaps it's
an easy fix" - but, against that, I don't really want to be fiddling
about with lasers when I'm not sure what I'm doing - and I've plenty of
other fruitless-but-engaging jobs to spend my time on.
Adrian

On 01/12/16 08:43, Brian Gaff wrote:
That sounds a bit naff. I wonder if there are any of the stage devices going
second hand. Even back in the 80s some of these seemed to be able to run all
the time with little issues out of dooors and in the rain, at least when I
could see back then raindrops and lasers made for a very interesting almost
strobe droplets slow motion effect.
Brian


I don't mind a house going full chav, ie covered with illuminations: the
owner has made an effort and even if I don't like it personally, I
expect the local kids love it.

It's "half chav" that's horrid - one manky illuminated Rudolph dangling
from the gutters...

It's "half chav" that's horrid - one manky illuminated Rudolph
dangling from the gutters...


Love the "Half Chav" term. But could be a potential "Full Chav" in a few
years.

On Thursday, 1 December 2016 09:53:37 UTC, Tim Watts wrote:
It's "half chav" that's horrid - one manky illuminated Rudolph dangling
from the gutters...

.... in March.

Owain

On 30/11/2016 18:00, Adrian Brentnall wrote:
HI All
I was prompted to investigate these - we like to illuminate the outside
(& inside!) of the house, and these looked like a good idea.
The one I purchased allegedly had two lasers (red & green) and four
different effects.
Trouble is - this one seems to be faulty - the ebay seller has refunded
my money (bless 'em).
The unit has a waterproof momentary push-button on the back, it seems to
need a press in order to start the thing working - which is kind of
inconvenient as our outdoor lights are usually on a timer, and, even if
this unit was working properly, I can't see me nipping outside every
night just to push the button!
Just wondering if anybody else has one of these new-fangled units - and
whether theirs starts automatically when mains is switched on, or if
it's a elfin-safety feature of the unit that it requires a digit on the
button to start the lasers?
The very thin user manual also says that the unit needs to be switched
'off' to cool down for 30 minutes after 5 hours of running... this
particular unit doesn't run for more than a minute or so before cutting
out, so it's kind of academic g
Any real-life experiences, please?
Thanks
Adrian

I have just bought such a beast with the intention of it being switched
on tonight and left on for a few hours for the first time. I bought mine
from TLC along with a few extra Icicle connectable sets.

No limitations of use in the instructions.

Mike

On 01/12/2016 14:00, Muddymike wrote:
On 30/11/2016 18:00, Adrian Brentnall wrote:
HI All
I was prompted to investigate these - we like to illuminate the outside
(& inside!) of the house, and these looked like a good idea.
The one I purchased allegedly had two lasers (red & green) and four
different effects.
Trouble is - this one seems to be faulty - the ebay seller has refunded
my money (bless 'em).
The unit has a waterproof momentary push-button on the back, it seems to
need a press in order to start the thing working - which is kind of
inconvenient as our outdoor lights are usually on a timer, and, even if
this unit was working properly, I can't see me nipping outside every
night just to push the button!
Just wondering if anybody else has one of these new-fangled units - and
whether theirs starts automatically when mains is switched on, or if
it's a elfin-safety feature of the unit that it requires a digit on the
button to start the lasers?
The very thin user manual also says that the unit needs to be switched
'off' to cool down for 30 minutes after 5 hours of running... this
particular unit doesn't run for more than a minute or so before cutting
out, so it's kind of academic g
Any real-life experiences, please?
Thanks
Adrian

I have just bought such a beast with the intention of it being switched
on tonight and left on for a few hours for the first time. I bought mine
from TLC along with a few extra Icicle connectable sets.

No limitations of use in the instructions.

Mike
I'd be interested to hear how you get on.

This one is branded "Christmas Workshop" and is item no 89180...

Even if it had worked for more than a few minutes, the need to trot
outside and press a button to start it up, rather than just turning on
the mains to it, would have been a bit of a pain.

It also has a photocell in the business end of the projector, that stops
the thing from running unless it's "dark enough" - but doesn't seem to
allow it to run again the next time it gets "dark enough" (like the
following night...
Seems to have been thought out oddly... or maybe not at all?

Adrian

On 01/12/2016 14:32, Adrian Brentnall wrote:
No limitations of use in the instructions.

Mike
I'd be interested to hear how you get on.

This one is branded "Christmas Workshop" and is item no 89180...

Even if it had worked for more than a few minutes, the need to trot
outside and press a button to start it up, rather than just turning on
the mains to it, would have been a bit of a pain.

"Christmas Workshop" is a brand name of Ben Ross, who are one of the
el-cheapo importers.

Kind regards

Mike

On 01/12/2016 17:06, Muddymike wrote:
On 01/12/2016 14:32, Adrian Brentnall wrote:
No limitations of use in the instructions.

Mike
I'd be interested to hear how you get on.

This one is branded "Christmas Workshop" and is item no 89180...

Even if it had worked for more than a few minutes, the need to trot
outside and press a button to start it up, rather than just turning on
the mains to it, would have been a bit of a pain.

"Christmas Workshop" is a brand name of Ben Ross, who are one of the
el-cheapo importers.

Kind regards

Mike
HI Mike
Yes - I found that out already g - that's where the trail went dead...
Not going to be a lot of 'tech support' available from them, then..
Thanks
Adrian

On Thu, 1 Dec 2016 09:53:32 +0000, Tim Watts wrote:

I don't mind a house going full chav, ie covered with illuminations: the
owner has made an effort and even if I don't like it personally, I
expect the local kids love it.

A surfet of static and/or random flashing lights is naff, full stop.
If you are going to do it do it properly, set and timed to music:

https://www.youtube.com/watch?v=90oZ52M4IC0

https://www.youtube.com/watch?v=g_hXlKCt11s How to... but uses pixel
LEDS.

Currently have a Pi Zero directly controlling three short strings (4
ordinary bright white LEDs/string salavged from a cheap decoration
SWMBO'd didn't like) with PWM and transistor switch per string. I
might see what the current draw of the outdoor LED lights we normally
use is and hack off the basic controller and replace it with a Pi to
give sequences and effects that we like.

Using pixel LEDs seems cheating some how, but simple LED strings
can't do what they can do.

--
Cheers
Dave.

On 02/12/16 18:19, Dave Liquorice wrote:
On Thu, 1 Dec 2016 09:53:32 +0000, Tim Watts wrote:

I don't mind a house going full chav, ie covered with illuminations: the
owner has made an effort and even if I don't like it personally, I
expect the local kids love it.

A surfet of static and/or random flashing lights is naff, full stop.
If you are going to do it do it properly, set and timed to music:

https://www.youtube.com/watch?v=90oZ52M4IC0

https://www.youtube.com/watch?v=g_hXlKCt11s How to... but uses pixel
LEDS.

Bloody hell! That's doing it properly!

All he needs is a couple of musical giant tesla coils to finish that
(and see off the burglars).

Currently have a Pi Zero directly controlling three short strings (4
ordinary bright white LEDs/string salavged from a cheap decoration
SWMBO'd didn't like) with PWM and transistor switch per string. I
might see what the current draw of the outdoor LED lights we normally
use is and hack off the basic controller and replace it with a Pi to
give sequences and effects that we like.

Using pixel LEDs seems cheating some how, but simple LED strings
can't do what they can do.


I thought he'd be doing something like that.

He says he's using the: WS2811 - you can get RGB LEDs with that
integrated to even avoid the need for a PCB (or at least all it would do
is act as mounting and a wire carrier). I suspect his setup predates
that LED, maybe - but if anyone wants to try this, the WS2812B LED works
in the same way - and you can buy them mounted on tape (from the USA)
for reasonable coin).


I wonder why all the crazy good stuff like this is always an american?

"Tim Watts" wrote in message
...
On 02/12/16 18:19, Dave Liquorice wrote:
On Thu, 1 Dec 2016 09:53:32 +0000, Tim Watts wrote:

I don't mind a house going full chav, ie covered with illuminations: the
owner has made an effort and even if I don't like it personally, I
expect the local kids love it.

A surfet of static and/or random flashing lights is naff, full stop.
If you are going to do it do it properly, set and timed to music:

https://www.youtube.com/watch?v=90oZ52M4IC0

With any luck the neighbours will murder them in days.

https://www.youtube.com/watch?v=g_hXlKCt11s How to... but uses pixel
LEDS.

And from that you can see why the pros waltz
around instead of looking like a stuffed dummy...

Bloody hell! That's doing it properly!

All he needs is a couple of musical giant tesla coils to finish that (and
see off the burglars).

Currently have a Pi Zero directly controlling three short strings (4
ordinary bright white LEDs/string salavged from a cheap decoration
SWMBO'd didn't like) with PWM and transistor switch per string. I
might see what the current draw of the outdoor LED lights we normally
use is and hack off the basic controller and replace it with a Pi to
give sequences and effects that we like.

Using pixel LEDs seems cheating some how, but simple LED strings
can't do what they can do.


I thought he'd be doing something like that.

He says he's using the: WS2811 - you can get RGB LEDs with that integrated
to even avoid the need for a PCB (or at least all it would do is act as
mounting and a wire carrier). I suspect his setup predates that LED,
maybe - but if anyone wants to try this, the WS2812B LED works in the same
way - and you can buy them mounted on tape (from the USA) for reasonable
coin).

On 02/12/16 19:54, Tim Watts wrote:
On 02/12/16 18:19, Dave Liquorice wrote:
On Thu, 1 Dec 2016 09:53:32 +0000, Tim Watts wrote:


A surfet of static and/or random flashing lights is naff, full stop.
If you are going to do it do it properly, set and timed to music:

https://www.youtube.com/watch?v=90oZ52M4IC0

https://www.youtube.com/watch?v=g_hXlKCt11s How to... but uses pixel
LEDS.

Using pixel LEDs seems cheating some how, but simple LED strings
can't do what they can do.


I thought he'd be doing something like that.

He says he's using the: WS2811 - you can get RGB LEDs with that
integrated to even avoid the need for a PCB (or at least all it would do
is act as mounting and a wire carrier). I suspect his setup predates
that LED, maybe - but if anyone wants to try this, the WS2812B LED works
in the same way - and you can buy them mounted on tape (from the USA)
for reasonable coin).


I just watched another of Matt Johnson's videos and it seems he buys the
"pixels" (individual light unit) ready made from a dude on Guanzhong via
Aliexpress.

That makes it seem much more doable - I was thinking "how did he get the
time to make 1000's of lights and wire them up...

Tim Watts wrote:

I just watched another of Matt Johnson's videos and it seems he buys the
"pixels" (individual light unit) ready made from a dude on Guanzhong via
Aliexpress.

Last year I added a PCB with 8 LED pixels to an aliexpress order, just
to see how easy they are to drive.

I found they were easy enough to drive from a USB-serial adapter
(admittedly a specialised one that can do sync as well as async) and
knocked up a little python program to run through a few effects, so I
bought a 200 pixel length of LED tape as part of another aliexpress
order ... now's probably the time to dig them out.

On 03/12/16 09:25, Andy Burns wrote:
Tim Watts wrote:

I just watched another of Matt Johnson's videos and it seems he buys the
"pixels" (individual light unit) ready made from a dude on Guanzhong via
Aliexpress.

Last year I added a PCB with 8 LED pixels to an aliexpress order, just
to see how easy they are to drive.

I found they were easy enough to drive from a USB-serial adapter
(admittedly a specialised one that can do sync as well as async) and
knocked up a little python program to run through a few effects, so I
bought a 200 pixel length of LED tape as part of another aliexpress
order ... now's probably the time to dig them out.


This is the supplier the bloke in the video used:

https://www.aliexpress.com/store/gro...506643321.html

How can it be so cheap?

Anyway - I feel some fun coming on next Xmas

Nothing like Matt's - probably just a tree in the garden, or the edges
of the front of the house of something.

I think those chips drive the same way as the Pi's Unicorn Hat (latter
uses the LEDs with the built in chip rather than the external one, but
given the basic drive is the same (the whole string is a giant D-shift
latch register with D-in and D-out on each lamp - I suspect the protocol
is the same.

A Pi can drive one such data line directly using one of the DMA
controlled pulse shaping IO pins - but you usually need a level shifter
to gi from 5V to 12V for the lamps.

So in theory, if you can devote one Pi to a string, the Unicorn Hat
library should do the job - I've played with that and it's dead easy.

In a way, it might make the setup easier to use 1 Pi per string - write
a super simple daemon that sits on Wifi and accepts various pattern
requests and plays them out to the string.

At that point, you could even run the string and Pi in a weatherproof
box off a car battery (obviously with a 5V regulator for the Pi). It
would make the temporary installation even easier that Matt's.

Tim Watts wrote:

This is the supplier the bloke in the video used:
https://www.aliexpress.com/store/gro...506643321.html

Yes, pretty cheap, can't remember what I paid last year (Chinese new
year discounts).

I think those chips drive the same way as the Pi's Unicorn Hat

You drive them with varying width pulses (long high followed by short
low is a "1", short high followed by long low is a "0") each pixel
re-clocks the output to the next in the chain.

Timing is quite tight to within about 150ns, the adafruit library does
it by setting a 6MHz clock, and using a whole byte of 0b11111000 for the
"1" or 0b11100000 for the "0" pulse, so each RGB triplet takes 24 bytes
to send the 24 pulses per pixel, the USB block transfer size means this
is limited to about 340 pixels.

I realised I could set the clock to 2.4MHz on my USB dongle and just
send three bits per pulse either 0b110 for "1" or ob100 for "0" so just
8 bytes per RGB triplet, theoretically I could run 2400 pixels and the
timing works out closer to the ideal pulse width.

A Pi can drive one such data line directly using one of the DMA
controlled pulse shaping IO pins - but you usually need a level shifter
to gi from 5V to 12V for the lamps.

My strips are 5V powered, but I still need a 3.3-5.0 level shifter for
the clock signal.

In a way, it might make the setup easier to use 1 Pi per string - write
a super simple daemon that sits on Wifi and accepts various pattern
requests and plays them out to the string.

For now I just run the python script on a netbook, hooked by USB to the
sync converter, in fact I was powering the small strip of 8 pixels from
the USB too. I found all the various components and hooked them back
together, found I could power 24 pixels of my longer strip, any more
than that sagged the voltage so much it started "crashing" the pixels
i.e. they weren't clocking and re-sending the data reliably.

So I need to dig out a 5V 3A PSU to power the LEDs not from the USB,
then I can work on some more impressive patterns for the full strip.

Fun stuff.

On 03/12/16 20:38, Andy Burns wrote:
Tim Watts wrote:

This is the supplier the bloke in the video used:
https://www.aliexpress.com/store/gro...506643321.html


Yes, pretty cheap, can't remember what I paid last year (Chinese new
year discounts).

I think those chips drive the same way as the Pi's Unicorn Hat

You drive them with varying width pulses (long high followed by short
low is a "1", short high followed by long low is a "0") each pixel
re-clocks the output to the next in the chain.

Timing is quite tight to within about 150ns, the adafruit library does
it by setting a 6MHz clock, and using a whole byte of 0b11111000 for the
"1" or 0b11100000 for the "0" pulse, so each RGB triplet takes 24 bytes
to send the 24 pulses per pixel, the USB block transfer size means this
is limited to about 340 pixels.

I realised I could set the clock to 2.4MHz on my USB dongle and just
send three bits per pulse either 0b110 for "1" or ob100 for "0" so just
8 bytes per RGB triplet, theoretically I could run 2400 pixels and the
timing works out closer to the ideal pulse width.

Nice move


A Pi can drive one such data line directly using one of the DMA
controlled pulse shaping IO pins - but you usually need a level shifter
to gi from 5V to 12V for the lamps.

My strips are 5V powered, but I still need a 3.3-5.0 level shifter for
the clock signal.

Sorry - yes. You're right. I forgot the Pi's GPIO were at 3.3V.


In a way, it might make the setup easier to use 1 Pi per string - write
a super simple daemon that sits on Wifi and accepts various pattern
requests and plays them out to the string.

For now I just run the python script on a netbook, hooked by USB to the
sync converter, in fact I was powering the small strip of 8 pixels from
the USB too. I found all the various components and hooked them back
together, found I could power 24 pixels of my longer strip, any more
than that sagged the voltage so much it started "crashing" the pixels
i.e. they weren't clocking and re-sending the data reliably.

So I need to dig out a 5V 3A PSU to power the LEDs not from the USB,
then I can work on some more impressive patterns for the full strip.

Fun stuff.

On 03/12/16 20:38, Andy Burns wrote:

For now I just run the python script on a netbook, hooked by USB to the
sync converter, in fact I was powering the small strip of 8 pixels from
the USB too. I found all the various components and hooked them back
together, found I could power 24 pixels of my longer strip, any more
than that sagged the voltage so much it started "crashing" the pixels
i.e. they weren't clocking and re-sending the data reliably.

So I need to dig out a 5V 3A PSU to power the LEDs not from the USB,
then I can work on some more impressive patterns for the full strip.

I was going to add, before my finger hit send - I wonder how long a
strip you could run before the data line gets too corrupted. 100 on
cable (I'm guessing 10m?) seems find - but I wonder how much longer you
could go, assuming sufficient 5V/12V power.

Tim Watts wrote:

I was going to add, before my finger hit send - I wonder how long a
strip you could run before the data line gets too corrupted.

I think there's no absolute limit, my strip of 144 (not 200 like I
though) takes 75mA for the inbuilt chips with all pixels off.

Each pixel regenerates a clean version of the pulse-train to its
neighbour, in my case the limit is the USB block size, once you hit that
you would get a long enough gap in the pulses that the pixels at the
"head" of the chain would start listening for new colours, rather then
silently echoing them down the line, which is how you start a new "frame".

On 03/12/16 21:21, Andy Burns wrote:
Tim Watts wrote:

I was going to add, before my finger hit send - I wonder how long a
strip you could run before the data line gets too corrupted.

I think there's no absolute limit, my strip of 144 (not 200 like I
though) takes 75mA for the inbuilt chips with all pixels off.

Each pixel regenerates a clean version of the pulse-train to its
neighbour,

Ah - that would help a lot... And a bit thick of me not to realise,
seeing as the Dout comes from the chip!

in my case the limit is the USB block size, once you hit that
you would get a long enough gap in the pulses that the pixels at the
"head" of the chain would start listening for new colours, rather then
silently echoing them down the line, which is how you start a new "frame".


The USB block thingy would be a bit of a heisenbug if you didn;t already
suspect it - imagine trying to trace that!

This is the driver/ethernet interface Matt used:

http://www.sandevices.com/E681info.html

It's actually quite cost effective if you are driving a boat load and
can run cables out from a single location for a group.

But I still like the Pi idea...

On 03/12/16 21:39, Tim Watts wrote:

http://www.sandevices.com/E681info.html

It's actually quite cost effective if you are driving a boat load and
can run cables out from a single location for a group.

But I still like the Pi idea...

I looked at that - and it seems to use something called DMX over
Ethernet aka E1.31 aka ArtNet(?).

I can find no meaningful examples of how to talk ArtNet(etc), except for
a very complete protocol definition (it is royalty free) - so that meant
dozens of pages of a very complex looking protocol. Without a clear
simple example, it's hard to know how easy/hard in practise it would be.

All the videos seem to be:

1) How to wire up pixel strings;

2) How to wire up E1.31 bridge.

3) Stick a Pi on it.

???

5) Profit!

If *I* were doing this, I think I would stick to my Pi idea - it would
probably be easier to invent your own simple text protocol, rather than
try to understand and drive E1.31! It looks very clever and very
suitable for full on theatrics (and efficient in its use of multicast).

I suppose it depends on how well timed your sequences need to be - if
you are running 10 strings in chaser mode, that must be 100% lockstep,
E1.31 looks like it is well designed for this. It might be harder to get
that sort of synchronisation over WIFI via a few Pi controllers.

Tim Watts wrote:

http://www.sandevices.com/E681info.html

I suppose once you get past the low hundreds of devices, it makes sense
to split it into multiple blocks with a dedicated controller looking
after them.

I looked at that - and it seems to use something called DMX over
Ethernet aka E1.31 aka ArtNet(?).

DMX and DALI I've heard of, but not E1.31

If *I* were doing this, I think I would stick to my Pi idea

Yes if I had a Pi I'd use it instead of USB-sync, just do your own
bit-banging, you could probably drive 8 strings of RGB LEDs per GPIO port.

Andy Burns wrote:

DMX and DALI I've heard of

See also "Mikes electric stuff" on youtube for impressive commercial
stuff in the UK.

On 03/12/16 22:23, Andy Burns wrote:
Tim Watts wrote:

http://www.sandevices.com/E681info.html

I suppose once you get past the low hundreds of devices, it makes sense
to split it into multiple blocks with a dedicated controller looking
after them.

I looked at that - and it seems to use something called DMX over
Ethernet aka E1.31 aka ArtNet(?).

DMX and DALI I've heard of, but not E1.31

If *I* were doing this, I think I would stick to my Pi idea

Yes if I had a Pi I'd use it instead of USB-sync, just do your own
bit-banging, you could probably drive 8 strings of RGB LEDs per GPIO port.


I wonder how practical that would be - bit banging at 400kHz (is that
right - it's been a while?) - seems a pretty realtime operation for a
full on OS like linux (unless you actually use RT features or write it
as a kernel driver or something???

Tim Watts wrote:

Andy Burns wrote:

do your own bit-banging, you could probably drive 8 strings of RGB
LEDs per GPIO port.

I wonder how practical that would be - bit banging at 400kHz (is that
right - it's been a while?)

800kHz

Does a Pi have DMA based GPIO?

seems a pretty realtime operation for a full on OS like linux (unless
you actually use RT features or write it as a kernel driver or
something???

Can't remember the name (banana pi? Latte Panda?) but oneof the
pi-alikes has an arduino "slave" onboard, which could do the bitwise
I/O, while the linuxy section decided what colours to send.

On 03/12/16 22:59, Andy Burns wrote:
Tim Watts wrote:

Andy Burns wrote:

do your own bit-banging, you could probably drive 8 strings of RGB
LEDs per GPIO port.

I wonder how practical that would be - bit banging at 400kHz (is that
right - it's been a while?)

800kHz

Blimey! I would not feel confident of bitbanging that in ordinary userland.

Does a Pi have DMA based GPIO?

Yes: GPIO 18 in DMA-PWM mode.

I did look at the Adafruit library for this and IIRC it does as you
described earlier: Has one byte per bit, describing the mark/space of
one PWM pulse. Load up 24xNumLEDs bytes into RAM and let it rip. Do
whatever at the end to cause the registers to be latched to the LED
drive outputs.

I think the Pi only has one such pin so you only get to do one chain
this way.

seems a pretty realtime operation for a full on OS like linux (unless
you actually use RT features or write it as a kernel driver or
something???

Can't remember the name (banana pi? Latte Panda?) but oneof the
pi-alikes has an arduino "slave" onboard, which could do the bitwise
I/O, while the linuxy section decided what colours to send.


That would be elegant. It's the sort of job an 8pin Atmel AVR could
probably manage too for £3 and some really simple programming, assuming
the clock goes high enough (20MHz being the tinyAVR max) to handle bit
banging with reliable timing - OR if it's onboard PWM is upto the job (I
thought tinyAVR PWM was limited to a single mark/space until
reprogrammed, rather than being able to ramp through RAM - but my
experience of PWM on AVRs is minimal)


4k RAM would allow for RGB on over 1000 LEDs leaving working space as
you'd not be using the more wasteful method of the Pi PWM.

I wonder how easy it would be to link it to the over I2C... You only
really need 3-4 commands: SetNumLEDs; SetLEDXwithRGB; BulkLoadBuffer;
SendBufferToLEDs

It does sound a rather neat way of doing it

If that were viable, making a custom "HAT" with 1/2 dozen of these on
board would be pretty cool.

Tim Watts wrote:

Load up 24xNumLEDs bytes into RAM and let it rip. Do
whatever at the end to cause the registers to be latched to the LED
drive outputs.

They latch one-by-one not all at once, e.g starting from an idle state

the first LED (well all of them) is listening for the combined
clock/data to start,

it receives the first 24 pulses without echoing them,
and latches those as its colour,

after that it receives and echoes every pulse it hears to the next LED
until it sees the pulses have stopped,

when it goes back to waiting for a new colour for itself.

so an unbroken sequence of pulses will "fill up" consecutive LEDs with
colours, but a break in pulses starts back again with the first LED.

On 04/12/16 09:56, Tim Watts wrote:
On 03/12/16 22:59, Andy Burns wrote:
Tim Watts wrote:

Andy Burns wrote:

do your own bit-banging, you could probably drive 8 strings of RGB
LEDs per GPIO port.

I wonder how practical that would be - bit banging at 400kHz (is that
right - it's been a while?)

800kHz

Blimey! I would not feel confident of bitbanging that in ordinary userland.

Does a Pi have DMA based GPIO?

Yes: GPIO 18 in DMA-PWM mode.

I did look at the Adafruit library for this and IIRC it does as you
described earlier: Has one byte per bit, describing the mark/space of
one PWM pulse. Load up 24xNumLEDs bytes into RAM and let it rip. Do
whatever at the end to cause the registers to be latched to the LED
drive outputs.

I think the Pi only has one such pin so you only get to do one chain
this way.

seems a pretty realtime operation for a full on OS like linux (unless
you actually use RT features or write it as a kernel driver or
something???

Can't remember the name (banana pi? Latte Panda?) but oneof the
pi-alikes has an arduino "slave" onboard, which could do the bitwise
I/O, while the linuxy section decided what colours to send.


That would be elegant. It's the sort of job an 8pin Atmel AVR could
probably manage too for £3 and some really simple programming, assuming
the clock goes high enough (20MHz being the tinyAVR max) to handle bit
banging with reliable timing - OR if it's onboard PWM is upto the job (I
thought tinyAVR PWM was limited to a single mark/space until
reprogrammed, rather than being able to ramp through RAM - but my
experience of PWM on AVRs is minimal)


4k RAM would allow for RGB on over 1000 LEDs leaving working space as
you'd not be using the more wasteful method of the Pi PWM.

I wonder how easy it would be to link it to the over I2C... You only
really need 3-4 commands: SetNumLEDs; SetLEDXwithRGB; BulkLoadBuffer;
SendBufferToLEDs


And some optimising commands maybe:

BulkLoadBuffer(OffSet) to allow for simple chasers (offset=0,1,2,0...)
and switching between banks of preloaded sets if RAM vs NumLEDs permits.

On 04/12/16 10:19, Andy Burns wrote:
Tim Watts wrote:

Load up 24xNumLEDs bytes into RAM and let it rip. Do
whatever at the end to cause the registers to be latched to the LED
drive outputs.

They latch one-by-one not all at once, e.g starting from an idle state

With respect, are you *certain* of that? I was reading the spec sheet of
the one in the Unicorn Hat and I seem to recall a clever almost
synchronous signal that was used to latch the register to the outout driver.

But that could be a fabrication of my imagination - I'll have to go bac
to the sheet...


the first LED (well all of them) is listening for the combined
clock/data to start,

it receives the first 24 pulses without echoing them,
and latches those as its colour,

after that it receives and echoes every pulse it hears to the next LED
until it sees the pulses have stopped,

when it goes back to waiting for a new colour for itself.

so an unbroken sequence of pulses will "fill up" consecutive LEDs with
colours, but a break in pulses starts back again with the first LED.


You see, I *thought* that break was used to clock the stored value
through to the driver?? OK, you need 3 registers for that.

I might well be very mistaken...

On Sat, 3 Dec 2016 11:03:04 +0000, Tim Watts wrote:

How can it be so cheap?

It's China, I've got my eye on a 5 m 240 pixel IP65 strip on Amazon
for £23.00...

Nothing like Matt's - probably just a tree in the garden, or the edges
of the front of the house of something.

I just want something does a bit more than flash/fade simple
sequences. I suspect it won't pass management approval what ever I
do. I'd like it to do the simple "ordinary" things but also do
something to make people notice and think "Hey! That's different".

A Pi can drive one such data line directly using one of the DMA
controlled pulse shaping IO pins

There is one hardware PWM GPIO on a Pi but there is also libs that
provide software PWM on any GPIO. My three channels uses the hardware
PWM GPIO and two software ones. Each channel has it's own thread in
my Python program so they operate completely independantly. Each
thread also has a queue so you can adjust the fade up time, on time,
fade down time, off time and the LED level for "on" and "off", all on
the fly. Each thread then just loops round repeating that pattern.

- but you usually need a level shifter to gi from 5V to 12V for the
lamps.

5 V strips seem very common but you still need to level shift from
the 3.3 V of the Pi GPIO.

In a way, it might make the setup easier to use 1 Pi per string - write
a super simple daemon that sits on Wifi and accepts various pattern
requests and plays them out to the string.

Might be able to run more than one string from a Pi, it would depend
on the Pi being able to run at 800 kHz software PWM, TBH I don't
think it will or only for only a couple of channels.

At that point, you could even run the string and Pi in a weatherproof
box off a car battery (obviously with a 5V regulator for the Pi). It
would make the temporary installation even easier that Matt's.

A full brightness strip showing white takes a fair bit of juice. Each
pixel draws around 60 mA (18.5 mA/LED), 240 pixels is as near as damn
it 15 A! Depending on the display patterns a car battery might not
last very long. And car batteries don't like being deep discharged
either.

--
Cheers
Dave.

On Sat, 3 Dec 2016 22:38:38 +0000, Tim Watts wrote:

I wonder how practical that would be - bit banging at 400kHz (is that
right - it's been a while?) - seems a pretty realtime operation for a
full on OS like linux (unless you actually use RT features or write it
as a kernel driver or something???

Out there some where is some code for bit banging on an aurdino. The
core is a bit of assembler that untilises the known number of clock
cycles per instruction to get the timing right. IIRC that assembler
is called as an interupt service routine. Getting the interupt rate
right might be tricky on a Pi as the clock isn't fixed.

--
Cheers
Dave.

On 04/12/16 20:04, Dave Liquorice wrote:
On Sat, 3 Dec 2016 11:03:04 +0000, Tim Watts wrote:

How can it be so cheap?

It's China, I've got my eye on a 5 m 240 pixel IP65 strip on Amazon
for £23.00...

Nothing like Matt's - probably just a tree in the garden, or the edges
of the front of the house of something.

I just want something does a bit more than flash/fade simple
sequences. I suspect it won't pass management approval what ever I
do. I'd like it to do the simple "ordinary" things but also do
something to make people notice and think "Hey! That's different".

A Pi can drive one such data line directly using one of the DMA
controlled pulse shaping IO pins

There is one hardware PWM GPIO on a Pi but there is also libs that
provide software PWM on any GPIO. My three channels uses the hardware
PWM GPIO and two software ones. Each channel has it's own thread in
my Python program so they operate completely independantly. Each
thread also has a queue so you can adjust the fade up time, on time,
fade down time, off time and the LED level for "on" and "off", all on
the fly. Each thread then just loops round repeating that pattern.

- but you usually need a level shifter to gi from 5V to 12V for the
lamps.

5 V strips seem very common but you still need to level shift from
the 3.3 V of the Pi GPIO.

In a way, it might make the setup easier to use 1 Pi per string - write
a super simple daemon that sits on Wifi and accepts various pattern
requests and plays them out to the string.

Might be able to run more than one string from a Pi, it would depend
on the Pi being able to run at 800 kHz software PWM, TBH I don't
think it will or only for only a couple of channels.

At that point, you could even run the string and Pi in a weatherproof
box off a car battery (obviously with a 5V regulator for the Pi). It
would make the temporary installation even easier that Matt's.

A full brightness strip showing white takes a fair bit of juice. Each
pixel draws around 60 mA (18.5 mA/LED), 240 pixels is as near as damn
it 15 A! Depending on the display patterns a car battery might not
last very long. And car batteries don't like being deep discharged
either.


24V makes a lot of sense with long LED strings, but I don't think anyone
has done a version of these addressable LEDs...

Dave Liquorice wrote:

Tim Watts wrote:

How can it be so cheap?

It's China, I've got my eye on a 5 m 240 pixel IP65 strip on Amazon
for £23.00...

I dug out a 4A/5V PSU and now have the 144 LEDs strung up in the window,
wish I'd ordered a few hundred more ... next year ... maybe poundland
will have them by then.

I just want something does a bit more than flash/fade simple
sequences. I suspect it won't pass management approval what ever I
do. I'd like it to do the simple "ordinary" things but also do
something to make people notice and think "Hey! That's different".

Just playing about re-jigging my patterns, provided I don't eat too much
CPU time on the PC with poorly coded functions, it pushes out about 300
"frames" per second. Loop unrolling type optimisations are a bit
trickier when you're working in multiples of 9 bytes :-(

On 04/12/16 16:21, Tim Watts wrote:
On 04/12/16 10:19, Andy Burns wrote:
Tim Watts wrote:

Load up 24xNumLEDs bytes into RAM and let it rip. Do
whatever at the end to cause the registers to be latched to the LED
drive outputs.

They latch one-by-one not all at once, e.g starting from an idle state

With respect, are you *certain* of that? I was reading the spec sheet of
the one in the Unicorn Hat and I seem to recall a clever almost
synchronous signal that was used to latch the register to the outout
driver.

But that could be a fabrication of my imagination - I'll have to go bac
to the sheet...


Just read the data sheet again - lack of a schematic doesn't help, but I
think I'm wrong - there does not seem to be an extra latch.

On Sun, 4 Dec 2016 20:28:01 +0000, Tim Watts wrote:

A full brightness strip showing white takes a fair bit of juice.
Each
pixel draws around 60 mA (18.5 mA/LED), 240 pixels is as near as
damn
it 15 A! Depending on the display patterns a car battery might not
last very long. And car batteries don't like being deep discharged
either.

24V makes a lot of sense with long LED strings, but I don't think anyone
has done a version of these addressable LEDs...

I don't think there are any 24 V LEDs ... Higher driving voltage LED
strings have series connected LEDs which makes controling each one
individually a bit tricky.

I've investigated the "normal" set of lights we have in view of PWM
driving them from a Pi. 2 channels, 240 LEDs, 32 V drive. LEDs
arranged in 12 parallel connected blocks of 20 LEDs. Within a block
there are two 10 LED series connected chains from each channels drive
to a common rail.

The rating plate says total 8.5 W @ 32 V, so I = 8.5/32 = 265 mA =
130+ mA per string. I only have a stock of small signal transistors
but do have some L293D H bridge drivers (up to 600 mA and 36 V).
However the control box must have some suitable switching and be
microprocessor controlled so just hacking into that is probably
easier.

--
Cheers
Dave.

Dave Liquorice wrote:

I just want something does a bit more than flash/fade simple
sequences. I suspect it won't pass management approval what ever I
do. I'd like it to do the simple "ordinary" things but also do
something to make people notice and think "Hey! That's different".

Personally I don't want any fast switching, I far prefer slow
transitions and colour morphing, of which there seems to be
limited availability.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

On 05/12/16 07:17, Chris J Dixon wrote:
Dave Liquorice wrote:

I just want something does a bit more than flash/fade simple
sequences. I suspect it won't pass management approval what ever I
do. I'd like it to do the simple "ordinary" things but also do
something to make people notice and think "Hey! That's different".

Personally I don't want any fast switching, I far prefer slow
transitions and colour morphing, of which there seems to be
limited availability.

Chris


A quick calculation on the addressable LEDs indicates that it takes 80us
to load one up, so that's about a 30/sec refresh rate on a string of 300
which would give a nice fade.

On 05/12/16 02:44, Dave Liquorice wrote:
On Sun, 4 Dec 2016 20:28:01 +0000, Tim Watts wrote:

A full brightness strip showing white takes a fair bit of juice.
Each
pixel draws around 60 mA (18.5 mA/LED), 240 pixels is as near as
damn
it 15 A! Depending on the display patterns a car battery might not
last very long. And car batteries don't like being deep discharged
either.

24V makes a lot of sense with long LED strings, but I don't think anyone
has done a version of these addressable LEDs...

I don't think there are any 24 V LEDs ... Higher driving voltage LED
strings have series connected LEDs which makes controling each one
individually a bit tricky.

Hmm. I looked at the separate driver chip for the addressable, the
WS2811. It does seem to show 1 LED = 5V supply and 3 in series = 12V, so
that would explain some of the addressable tapes that have 1 pixel=3LEDs
as the addressable element (being 12V tapes).

I suppose one option would be to have a 4 wire system (24V, 5V, OV and
Data) and have a DC-DC converter module every X-LEDs to maintain the 5V
rail.

I'm thinking very long strings here...

I've investigated the "normal" set of lights we have in view of PWM
driving them from a Pi. 2 channels, 240 LEDs, 32 V drive. LEDs
arranged in 12 parallel connected blocks of 20 LEDs. Within a block
there are two 10 LED series connected chains from each channels drive
to a common rail.

The rating plate says total 8.5 W @ 32 V, so I = 8.5/32 = 265 mA =
130+ mA per string. I only have a stock of small signal transistors
but do have some L293D H bridge drivers (up to 600 mA and 36 V).
However the control box must have some suitable switching and be
microprocessor controlled so just hacking into that is probably
easier.