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16  Using Arduino / LEDs and Multiplexing / Re: Lost with 50w LEDs + PWM on: June 26, 2014, 07:57:32 pm
To answer the original question of how the pt4115 drivers work, they are constant current, switched power supplies.
The constant current is set by means of a selecting a specific value for the current sense resistor. Some of these drivers have a selection of several of these on board and the selection happens by means of solder jumpers.

There are a few interesting boards on that are possibly better than the small single channel ebay drivers linked in this thread:
17  Using Arduino / LEDs and Multiplexing / Re: Lost with 50w LEDs + PWM on: June 25, 2014, 07:36:23 pm
I am assuming you are referring to the pt4115 drivers available from ccc suppliers (cheap Chinese crap  smiley-grin ) on eBay.
These drivers are essentially a constant current switching power supply in buck configuration, meaning that the input voltage must be higher than the output voltage.
If you rapplication requires a higher output voltage (28V) than input voltage(12V) you need a boost configuration.
However, assuming by how you asked the question that you don't know too much about LED drivers, why don't you post your application and then we can see what alternatives are available ?
18  Using Arduino / Interfacing w/ Software on the Computer / Re: Arduino Nano + ENC28J60 + MQTT on: June 12, 2014, 08:45:18 pm
Were you going to post more detail so we would have an idea of what you a even hoping to accomplish ?
19  Using Arduino / Networking, Protocols, and Devices / Re: communication for small robotics projects on: June 01, 2014, 04:06:19 pm

I am wanting to get to arduinos to communicate with each other. I have heard of i2c and pwm signal and that pwm can be transmitted from an fm transmitter. What is the best communication method for wired and wireless communication. I have heard of xbees and other wireless communication modules but would like to build my own transmitters and receivers. Also if any one could explain to me how i2c and pwm SIGNAL work it would be appreciated.

Any help will appreciated.

How about you try to google some of that stuff. Do some homework. When you have more specific questions come back and ask!
20  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet and OSC on: May 14, 2014, 09:17:45 pm
The matter of fact is that  simply don't know whether a non-W5199/W5200 based Ethernet Shield will actually work at all. the danger is that you possibly spend weeks debugging something that at this time you don't have the necessary expertise to do so and then still are left with a non-working project.

Currently I can get a W51000 Ethernt Shield at Newegg for $10.34 Actual availability and pricing depends on where you live.

You mentioned that you have the three  receiving computers connected via wireless  LAN (I assume WiFi). Do you have the computers connected through a WiFi Access Point / Router ?
How would you want your Arduino to connect to the WiFi LAN? Per Ethernet Cable ?

Another thing you may want to do is to post your existing Arduino Code (in code prackets please. Use the # button above to do so.)

In general for my projects I don't use original Arduinos anymore as there are fully compatible, less expensive, more powerful and smaller product available with the Teensy boards
21  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet and OSC on: May 11, 2014, 07:10:19 pm
If you post material that helps us better understand what your project entails then maybe. smiley-wink

I believe  the ENC28J60  based Ethernet Shield is not the best choice. Most of my devices communicate via OSC/Ethernet but I have never used an Ethernet Shield with the ENC28J60 Chip. I'd suggest you get yourself either an original Ethernet Shield, or a clone using either the Wiznet W5100 or W5200 chip.
That'll greatly help getting your project completed. Using an Ethernet Shield that is not supported by the normal Arduino Ethernet library will only make things more difficult to debug, particularly for a beginner.!!!
22  Using Arduino / LEDs and Multiplexing / Re: Tiny Led driver/controller for 3watt leds on: April 23, 2014, 09:58:36 pm
There are several 3-channel high power constant current LED drivers available at Form the simple to the high tech
23  Using Arduino / Networking, Protocols, and Devices / Re: what is the best protocol to connect more than 512 devices to an arduino?? on: April 20, 2014, 11:15:17 am
I2C only has 127 addresses and some of those are reserved for other purposes and really aren't available.
The limitation of I2C comes from bus capacitance. That includes also the capacitance each device on the bus adds. Even with a bus extender you have to find a balance between overall bus length and number of devices 100+ devices AND 300 ft of bus lengt is rather unrealistic aside from falling sort for the number of devices you want to connect.

 I am not aware of any low cost bus system that can accommodate 512 devices.
24  Using Arduino / Networking, Protocols, and Devices / Arduino Ethernet Bonjour / ZeroConf Networking Library on: April 19, 2014, 07:34:25 am
Over the last few months I've been updating the Arduino EthernetBonjour library still available online at The original library was written for Arduino 0017 and required separate libraries for DNS and DHCP. With Arduino 1.x these are not required anymore as they are part of the Arduino Ethernet library.

The main reason for the overhaul is that the original library made 50+ calls directly to the W5100 Ethernet chip and as such was very hardware dependent. I had already upgraded it to work with Arduino 1.x and also to work  with the W5200  Ethernet Chip found for example on the WIZ820io Ethernet Module.

The new library is more or less hardware independent. Bonjour and its underlying mechanisms mDNS and DNS-SD use UDP as its base protocol. As such the overhauled library only works with calls to the read/write methods from the EthernetUDP. This should greatly help to adapt it to other hardware and I am hoping for support from the community. The CC3000 from Texas Instruments would be a good candidate.

The changes to the Bonjour library also necessitated the addition of a routine to the EthernetUDP library in order to allow sending UDP multicast messages, required to implement mDNS and DNS-SD. This has been very similarly discussed on the Arduino forum over a year ago

EthernetUDP.h needs these lines aded in the sensible places:

virtual uint8_t beginMulti(IPAddress, uint16_t); // initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use Sending UDP packets
friend class EthernetBonjourClass;

EthernetUDP.cpp need this added routine:

/* Start EthernetUDP socket, listening at local port PORT */
uint8_t EthernetUDP::beginMulti(IPAddress ip, uint16_t port) {

  for (int i = 0; i < MAX_SOCK_NUM; i++) {
    uint8_t s = W5100.readSnSR(i);
    if (s == SnSR::CLOSED || s == SnSR::FIN_WAIT) {
      _sock = i;

  if (_sock == MAX_SOCK_NUM)
    return 0;

  byte mac[] = {  0x01, 0x00, 0x5E, 0x00, 0x00, 0x00 };

  mac[3] = ip[1] & 0x7F;
  mac[4] = ip[2];
  mac[5] = ip[3];

//  byte mac[] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0xfb };

  W5100.writeSnDIPR(_sock, rawIPAddress(ip));
  W5100.writeSnDPORT(_sock, port);

  _remaining = 0;

  socket(_sock, SnMR::UDP, port, SnMR::MULTI);

  return 1;

As noted in the documentation on the original web site, the library compiles to a relatively large chunk of code and is aimed at bigger boards with more flash and ram memory. I don't own an Arduino Mega and in recent projects only have used Paul Stoffregen's Teensy boards .
The Examples provided in the library compile and work out of the box with a Teensy++2 <-> WIZ812MJ  and with a Teensy 3 <-> WIZ820io.

The new library is available here:
25  Using Arduino / LEDs and Multiplexing / Re: 10 W LED with Tinkerkit MOSFET on: March 05, 2014, 07:32:11 pm
8,4V DC - regulated ?  (should be)
Put a capacitor parallell to led.
PWM dutycycle out to MOSFET is 0/255..255/255
Post code and schematic..

It is the current that needs to be kept constant, not the voltage. Otherwise you'll kill the LED in time.
26  Using Arduino / Networking, Protocols, and Devices / Re: Reading a OSC message from Arduino on: March 03, 2014, 11:10:42 pm
You am actually have more luck using this library for your Ethernet shield :

It's API looks much closer to the Ethernet library than the on you linked to.
27  Using Arduino / Networking, Protocols, and Devices / Re: Reading a OSC message from Arduino on: March 03, 2014, 06:58:35 pm
there are several reasons why this does not work:

1. The readme on the CNMat site says "- Sends and receives OSC packets over transport layers that implements the Arduino Stream Class such as Serial and  Ethernet UDP" I don't think the ENC28J60 library does that. EthernetUDP is part of the Ethernet library that works with the Ethernet Shield or in general with Shields and embedded Ethernet Modules that use an Wiznet W5100 or W5200 chip.
In essence the library that comes with the ENC28J60 would have to implement the pure virtual methods defined in  UDP.h. I haven't looked at it in detail but, again, I don't think it does that.

2. In order to use the OSCuino library you first have to receive a UDP package before you can fill the OSC message object with  msg.fiill.  Here is a little code snippet from one of my sketches that shoes how to receive a UDP packet and then fill the OSCmessage with msgIN.fill and then parse and route it to a callback function with msgIN.route().

void msgReceive(){
OSCMessage msgIN;
int size;
if((size = Udp.parsePacket())>0){
msgIN.route("/analog", handleAnalog);
msgIN.route("/digital", handleDigital);
28  Development / Other Software Development / Re: Windows/Linux/Mac Eclipse plugin to compile and upload arduino sketches on: March 01, 2014, 08:04:39 am
I have written detailed installation instruction for Mac users here:

These are to be followed precisely. If it says Arduino 1.5.2 then don't attempt to use 1.5.6 because it is more convenient ;-)

Also, I would really appreciate feedback on these instructions (there's a Windows version as well). I have anywhere between 40-50 visitors with 2-3 views per visitor on that section of my tiny blog and rarely receive any feedback. Occasionally a user asks question and needs help, but once I provide direction I don't necessarily receive feedback if it actually helped.
29  Using Arduino / Networking, Protocols, and Devices / Re: Cu Head and Cisco AP on: February 26, 2014, 12:46:58 pm
Qute frankly, I would put that WiFi shiled into the recycling bin.
The design of this shield is many years old and uses an embedded TCP stack that is not trivial to handle. I'fe tried this shiled almost 3 years ago and while I fibnally got it to connect, and send UDP packages, I ran into one obstacle after another.

In the meantime I have foud the most reliable solution is an Ethernet Shield comnnected to a WiFi ppocket route such as the TP-Link TL WR703n (or 702 or 3020).
If it needs to be physically smaller then use a Teensy ( connected to a WIZ820io.

Other than that a CC3000 perhas from Adafruit may do the job and is better software supported.
30  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet Shield vs Wifi Shield on: February 26, 2014, 12:40:51 pm
Being a newbie and wanting to finish a project like this within a week is illusory at best!!!
This project will require you to do software programming.

If it has to be WiFi then get an Ethernet Shield for the reasons already outlined and connect it to a littel relatively inexpensive pocket WiFi router such as the TP-Link WR702n, which can be had for less than $20.
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