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31  Using Arduino / Networking, Protocols, and Devices / Re: The best way to connect my mesh network to the company Wifi. on: February 21, 2014, 09:27:56 am
If you're looking for a potentially painful laerning experience then use the WiFi shield.

I personaly use have used an Ethernet Shield connected to a little WiFi pocket router in client/bridge mode. that combination, while more bulky, IMHO still offers the most flexibility and works out of the box. You can use the standard Ethernet library and all it offers in matured functionality. DHCP, DNS, mDNS etc.

As I mostly work with Teensy boards (  I now successfully have used a WIZ820io Ethernet module in conjunction with a TP-Link TL WR703n and TL WR702n in a few projects.

This solution is more functional solution and less expesive than the WiFi shield.
32  Development / Other Software Development / Re: Windows/Linux/Mac Eclipse plugin to compile and upload arduino sketches on: February 21, 2014, 06:39:28 am
You may want to dart with the instructions on my blog:
33  Using Arduino / Networking, Protocols, and Devices / Re: Multiple I2C sensors questions on: February 05, 2014, 09:14:28 pm
When you use different voltage levels it is good practice to use a  Level shifter. The one below for Adafruit should work fine:
This already includes 10k pull-up resistors.

It is really very simple to calculate pullup resistor values but requires a little bit of I2C bus spec. knowledge.
The I2C pins for normal mode (100KHz) and fast mode (400KHz) can only sink 3mA, which is also the reason why the overall bus capacitance should not exceed 400pF. Assuming a 5V I2C bus and A 1.8k resistor, according to ohm law  2.8 mA of current flow through the resistor. So in essence a 1k resistor is too low and the likelihood that the pins still are able to pull the I2C lines below the logic zero level is small.
34  Using Arduino / Networking, Protocols, and Devices / Re: I2C: Buffers, Pull-Up Resistors and Transmission over UTP Queries on: February 05, 2014, 08:49:52 pm
I suggested the PCA9600 because it is much more flexible and much faster and because I have a functioning board design tested to work on 20ft of CAT5 cable and 8 devices on the I2C bus at 1MHz showing still very crisp signals on a scope.

However, the chip you have selected should work fine for your application and  promises to be even simpler in application. For example it does not require the fast switching schottky diodes in my circuitry. The image I referenced is described as the quick design reference in the data sheet for the P82B715. I don't exactly know what your application is but I doubt you'll need the ESD protection diodes shown in the picture so all you are left with for a schematic are two chips and a few pull-up resistors.

I would not worry too much about the pairing. Just follow the schematic  shown in Fig 9 in the data sheet and you should be fine. That schematic does not show any decoupling caps either ;-)

Now go and build the thing and see if it works! Don't expect for it to work the first time. That of course does not mean that it won't but it is relatively normal that things have to be tweaked. Should you do run into problems, an oscilloscope is a very helpful tool to verify signal levels and signal Integrity. A logic analyzer is a very helpful tool to debug I2C protocol ( software) issues. For I2C bus purposes neither of these need to be particularly expensive. A good used analog scope for $50 from eBay is well worth the investment and plenty enough to verify I2C signal problems.
35  Using Arduino / LEDs and Multiplexing / Re: need help with 3w led wiring and high power arduino shield on: February 05, 2014, 07:32:29 pm
Don't wire LEDs in parallel. However when you flow this advice then you'll find that 8 x Vf is alway higher then the 12V from the computer. When something does not work as expected, turn of the power, take a step back and do some basic calculations.

The shield does not look like a constant current driver, which is what you need to drive LEDs. YourLED's might already be damaged if they've seen more than their rated max current.

Computer PSU's have the problem that they often do funny things when no load is applied to them. Not very good choice either.

Before making any more wiring attempts please browse through this section o the forum to brush up on your LED know how ;-)
36  Using Arduino / Programming Questions / Re: " 'analogWriteResolution()' was not declared in this scope " Error message on: February 03, 2014, 10:11:22 pm
The fully Arduino compatible Teensy 3 and Teensy 3.1 boards also provide this. At 1/4 the size and for a lot less money  smiley-cool
37  Using Arduino / Networking, Protocols, and Devices / Re: I2C: Buffers, Pull-Up Resistors and Transmission over UTP Queries on: February 03, 2014, 10:03:54 pm
Unless this is in a noisy (electrically) environment I don't think you'd need CAT6.
I my lighting systems I use pre-configured CAT5 cables with a PCA9600 I2C bus buffer and this works fine for up to 1MHz. I believe the max on the Arduino's is 400KHz so that would work fine on 20m.

The pull-up resistor configuration in Fig. 9 should work fine. Place the 470 Ohm resistors at each end of the bus. Or use a single 270Ohm pull-up resistor as shown in Fig 12.
The 4.7K on the Arduino side is a save value. The I2C pins for normal (100KHz) and fast mode (400KHz) pins only provide 3mA to discharge the cable(system) capacitance. Thus the limit to 400pF max system capacitance. Assuming a voltage of 5V and a pulp resistor of 1.8K result in a current of 28mA. 4.7K result in a current of 10mA according to Ohm law, so there is room to play.

Here is an excellent Article to the effect of varying pull-up resistors:
Everything Arduino <->I2C you'll find explained here:

In general I am not exactly sure why you chose the P82B715PN. You don't use other bus buffers in your system so thats one advantage that this buffer chip has that you cannot take advantage of in your system and it also does not isolate the bus capacitance which could help. I am thinking that a PCA9600 would be a better choice.
I could provide a schematic and a PCB layout that is breadboard ready.

The small board in the image below between the Ethernet Jack in the front and the Teensy 3 micro controller in the back hosts the PCA9600 I2C buffer chip, the Schottky diode and the necessary pull-up resistors. You'd need two of those little boards. One for each Arduino.
38  Development / Other Software Development / Re: Windows/Linux/Mac Eclipse plugin to compile and upload arduino sketches on: January 24, 2014, 07:18:12 pm

The Arduino Eclipse IDE bundles Eclipse Kepler and the plugin V2.2. No separate installation of the plugin is needed!
The only other software you have to install is Arduino IDE 1.5.2, or Arduino IDE 1.5.5 (NOT 1.5.4)

So, go ahead and compile and upload something ;-)
39  Development / Other Software Development / Re: Windows/Linux/Mac Eclipse plugin to compile and upload arduino sketches on: January 15, 2014, 10:28:16 pm
I've written some installation instructions for the newest version 2.2 and the new Arduino Eclipse IDE :

Particularly useful if you work on a mac and also want to program Teensy 3x boards! I've also installed the new Arduino Eclipse  IDE on Windows 7 and Ubuntu Linux, and find that the instructions should work for these as well.
40  Using Arduino / Networking, Protocols, and Devices / Re: Communicate with an iPhone through WiFi on: January 14, 2014, 06:38:29 pm
That's why I asked ;-)

The Ethernet->Router solution is dead simple and has the added advantage that you can use the mature Ethernet library which in turn is used by other Libraries.. Full Ad-Hoc or infrastructure abilities. Most routers are easy to configure per web interface, from the iPhone if you like.

A TP-Link WR702n costs $20-25 and a standard Ethernet Shield is maybe $30. Compare that with the price and functionality of the daead-on-arrival official  Arduino WiFi shield. You can get a little smaller, cheaper, and faster if you replace the Ethernet shield with a WIZ820io embedded Ethernet Module.

The only other small WiFi solution are breakout boards for the Texas Instruments CC3000. But then that module doesn't function as an AP either ( correct me if I am wrong, please!) and has to be connected to another router.

But even if WiFi provides more paths to a solution, the question with what application you are going to communicate and with which protocols is still not out of the world. You just have more options! I've chosen the OSC protocol and TouchOSC but that may not work at all for what you want to do.
41  Using Arduino / Networking, Protocols, and Devices / Re: Communicate with an iPhone through WiFi on: January 13, 2014, 10:11:12 pm
Besides the hardware, what software are you going to use to communicate with on the iPhone ?

42  Using Arduino / LEDs and Multiplexing / Re: Led Display on: January 06, 2014, 06:25:56 pm
While the OCTOWs library Paul has written for his Teensy3.x boards only works with Teensy boards the FastSPI2 library is also very popular for working with  WS28xx LED strings and also works on Megas. It's definitely fast enough to display still images ;-)
43  Using Arduino / LEDs and Multiplexing / Re: High Power RGB LED shield - 12bit/channel dimming - I2C (TWI) on: December 27, 2013, 09:09:44 pm
Finally, after a little eternity I've put my LED shield up for sale at

The difference to other offerings is that this shield is fully operated through the I2C bus (TWI) and requires only two pins (SDA, SCL) and GND. While the shield happily stacks in multiples on top of an Arduino Uno or Leonardo and most likely also a Yún and others it can be operated separately from the microprocessor.
So if your project requires:
  • independent control of more then 2 RGB LED's - it can do up to 64 -  and/or
  • a distributed system where each of the high power LEDs are many feet away from each other and/or
  • you need very smooth CIE lab brightness corrected dimming
Then this is what you are looking for.
Another "feature" is that these are assembled in the US, only use RoHS compliant, lead free solder solder and are fully function tested!

The best micro controller platform to use these with IMHO are the Teensy3.x as they have much more powerful I2C hardware than any Arduino I am aware of. They are fully Arduino compatible and Paul Stoffregen - the maker of these - is a very frequent contributor to the Arduino project.

I use a Teensy and these shields in my own lighting systems
44  Development / Other Hardware Development / Re: Led Stripe Light Organ / Flashing To Music / Need help on: December 26, 2013, 12:52:20 pm
There is a section on this forum entirely dedicated to LEDs and multiplexing. You may want to ask a moderator to move this thread to that section. You may get more responses :-)
45  Using Arduino / LEDs and Multiplexing / Re: Driving 750 or so leds, independently (of Course....why should this be easy?) on: December 26, 2013, 11:28:41 am
What speaks against using several length of LED strips instead of single LEDs ?

Using a Teensy3 or Teensy3.1 and the OCTOws library you can use thousands of LEDs at video refresh rates. The biggest project posted so far on the Teensy forum used in excess of 10000 LEDs in form of WS2811 led strips.
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