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106  Using Arduino / LEDs and Multiplexing / Re: OctoWS2811 Library - for large LED display at video speed refresh on: April 01, 2013, 05:25:56 am
What you're looking for is not Gamma correction, but CIE lab brightness correction, as the article at explains. However, the difference is relatively small and I am not sure if its visible.
I have a 12 bit version of it that I coupled post, and ther is also an 8 bit versioning the forum.
However, you can expect the 8 bit a bit ... Choppy.. At lower intensities due to limitation of resolution.
107  Using Arduino / LEDs and Multiplexing / Re: Random RGB Values Give Pastel Colors on: March 30, 2013, 08:28:29 pm
I actually have to revise what I had stated earlier. Clamping one of the values to 255 is not going to work. The way the rings are generated in my lighting system is that the optics in fromt of the LED head " clamps" one of the colors to zero.
So in essence if your algorithm chooses one of the three channels to clamp to zero and then you choose values randomly for the other two channels it'll work better.

However, the approach fungus has posted, selectin HSV and conveting it to RGB - while more complicated to implement and more computationally expensive - is by far the best approach!
108  Using Arduino / Networking, Protocols, and Devices / Re: Arduino WIFI on: March 28, 2013, 05:31:33 am
Somehow you missed at least  half of what I wrote  smiley-confuse I am not familiar with the ArdWiFi shield. Are you speaking about this device : ?

It looks to me that the WiFi module on that shield does NOT employ the WizNet W5100 WiFi chip from WizNet. So in essence, you''ll have to retire the ArdWiFi at least until you have a good bit more Arduino experience. Instead you need to get an Arduino Ethernet Shield. This one: You can get these relatively cheap at eBay for $20. A new original shield from Sparkfun will be about $45.

Then you need to obtain a TP-Link TL WR702n wireless router: for example at Amazon

As an alternative if it has to be a WiFi shield you could get the WiFly shield from Sparkfun Through two libraries - namely WiFly HQ and Ad=rdOSC for WiFly HQ this may support OSC but I have no personal experience with this hardware and cannot vouch for its function.

Once you have these devices (Ethernet Shield and router), let's continue the conversation.

The Ethernet library is !very! unlikely to work with your particular WiFi shield. It is meant to work directly with the original Arduino Ethernet shield that I've linked to above. The Arduino Bonjour library (that you can actually live without) relies directly on lower level functions of the Ethernet library. Any response you may have gotten from your WiFi shield does not involve any of these two libraries as they are hardware dependent on the presence of the WizNet W5100 chip.

Both, the ArdOSC library and the iOSCController library require the Ethernet library/shield.
109  Using Arduino / Networking, Protocols, and Devices / Re: connect an arduino to a server DNS/DHCP on: March 27, 2013, 08:16:49 pm
You may want to talk to the network admin of your school if that is even possible and if they'd allow it.
I could imagine plenty of reasons why they would not allow it ;-)
110  Using Arduino / Networking, Protocols, and Devices / Re: Arduino WIFI on: March 27, 2013, 08:14:03 pm
I Re- read your post. It appears that you had problems even for the iPhone to pick up the Arduino WiFi shield. This may also be an outdated statement but at least in the past the Arduino WiFi shield relied on ceiling an IP adds through DHCP from an existing WiFi router and then you could connect to the WiFishield through the router.

The Ethernet <-> TP-Link router does not have that problem. The router comes configured as an AP (Access Point). You plug it in and can connect to it right away with the iDevice of your choice!
111  Using Arduino / Networking, Protocols, and Devices / Re: Arduino WIFI on: March 27, 2013, 07:59:17 pm
I am afraid you've bitten off a bit more than you can chew at the moment, but don't despair.

You are missing a whole lot more than a few basics and I can say that because I've made this work and had to learn a few things the hard(ware) way.

My current state of knowledge about the Arduino WiFi shield, or better the current set of libraries do not yet support the UDP protocol and there have been a numer of posts about this unfortuante fact on the forum. But that may be different now. That is important because the OSC protocol generally is based on UDP and ArdOSC is no exception.

If the Arduino WiFi shield does support UDP, you have another few hurdles to take. ArdOSC makes use of some lower level functions of the original Ethernet shield library that talk directly to the W5100 Ethernet chip on the Ethenet Shield through SPI. You'd have to rewrite these functions for the specific hardware of the Arduino Wifi Shield.

The above are most of the hardware limitations. There is one more that has to do with the memory requirements of the involved software libraries so an Arduino version with more memory, e.g. a Mega would work if you need space for your own code.

However, you can deal with all of the above if you are not shy of getting different hardware. E.g. Get an Ethernet shield, so you can work with ArdOSC right out of the box. If you want WiFi, then connect a little pocket router to it. I've used a TP-Link TL WR703n and a 702n. I'd recommend the 702n as it has a English user interface (if you buy it through regular US sales channels) the interface for the 703n is all Chinese. You can get the Ethenet shield on eBay for about $20. As long as it has a W5100 chip on it you should be OK. The router will set you back about $25. Together, IMHO that provides you with a lot more mature functionality than any of the WiFi shield currntly available at a much petter price point.

The next thing you are missing is that the reason services show up in TouchOSC is because these are services that are announced through Bonjour
For TouchOSC to pick the Arduino up, you need to use the Arduino Bonjour library to register a service on the WiFi network that your iDevice is connected to.

BTW, the Bonjour Library also makes use of some lower level functions of the Ethernet shield library!

In my LED lighting systems instead of an Arduino I use the Arduino compatible Teensy++2 a WIZ812MJ Ethenet module and adapter also from PJRC. Together,  including the router, all that is less expensive than the Arduino WiFi shield alone!

So, if I have not severely scared the crap out of you and you still want to go ahead with your project and are not afraid of occasionally pulling out your hair and are ready for a few setbacks, in that case you are in the right ace here and I'd be glad to help you along. Once it starts working its actually pretty darned cool!!!

Perhaps start with what you actually want to achieve as an end result and  we'll go from there.
112  Using Arduino / LEDs and Multiplexing / Re: Random RGB Values Give Pastel Colors on: March 27, 2013, 05:53:27 am
Mike is correct, it does help  smiley-wink

This ( scroll down to the video) does exactly that. It randomly chooses 3 values and then clamps one of them to 255 and then fades from the last set of randomly chosen values to the new set.
113  Using Arduino / LEDs and Multiplexing / Re: PWM 3V 200mA High Power Led from 3v soure on: March 18, 2013, 05:39:58 pm

Apparently the only way is using a buck converter to ste-up the voltage and then use a CC driver?


A buck converter is a step down converter, not a step- up converter.
114  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet UDP or TCPIP examples on: March 11, 2013, 03:57:34 pm
If you want to connect the Arduino/TP-Link to your home router that's what you use the Client mode for. Then you can control the Arduino through your home router. If you want to connect from an IPad directly to the TP-Link router you need to put it into AP mode.

What application are you using on the iPad ?
115  Using Arduino / LEDs and Multiplexing / Re: Problem with PWM output and sensor input on: March 09, 2013, 10:32:04 am
No code, no help :-)

Please put the code in code tags by using the hash button (#)
116  Using Arduino / LEDs and Multiplexing / Re: led fader project on: March 08, 2013, 07:41:02 pm
The " standard" PWM frequency on the Arduno boards is 500 Hz. Frequencies over 100-120hz are not visible to most people.
It may have more to do with the 8- bit resolution of the Ardinos PWM signal in combination with the non linearity of the human brightness perception.

In my own projects I use an Led driver board with 12 bit resolution, allowing me a CIE brightness corrected dimming, alas at about 120Hz (IIRC) PWM frequency. Smooth as butter dimming without any perceivable flicker.
117  Using Arduino / Networking, Protocols, and Devices / Re: Wire lib vs I2C lib - interrupts, performance. on: March 05, 2013, 09:39:11 pm
The I2c library is faster than the wire library. The values presented in the table are code-size in bytes and duration of whatever write read function. The calculation you did assumes that the first number given is the number of bytes transferred per time, which, again , is not what the numbers represent.
The I2C signals are realized in hardware, thus the likelyhood that your application will have to wait because of the " blocking" behavior is very small. Removing dependence on interrupts makes this library more flexible to use as it eliminates its chance of interfering with other libraries that may also want to use the same interrupts.

The reason this library worked better for me was because of the timeout and reset, a function the wire library does it offer, or at least did not when I write the software for my prject.
118  Using Arduino / LEDs and Multiplexing / Re: OctoWS2811 Library - for large LED display at video speed refresh on: March 03, 2013, 06:46:21 am
Hi Paul,

Pretty stellar work from you. as usual!
What you need is not a gamma correction but CIE lightness correction :
I've seen lookup tables for the above on the forum usually in 8 bit resolution and have one in 12 bit used for my LED shields for my projects

Even better would be true CIE lab color correction:
119  Using Arduino / LEDs and Multiplexing / Re: LED project help on: March 02, 2013, 09:53:03 am
The 20feet of CAT5 cable for the PWM would worry me a bit was well. I would expect some signal degradation particularly if the PWM is running at higher fequencies.
120  Using Arduino / LEDs and Multiplexing / Re: Full brightness multiplexing. on: March 01, 2013, 06:01:50 pm
The human eye is more sensitive to green light, so green LED usually appear brighter than the red, or the blue.
This article may also of interest if brightness perception is an issue:
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