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Member Since 17 Sep 2011
Offline Last Active Dec 27 2012 11:00 PM

Posts I've Made

In Topic: A first chance exception of type 'System.Exception'

15 October 2012 - 05:03 PM

I can duplicate supra's issue. It occurs on the open port call below. And just for grins, after updating all the appropriate firmware, I was able to blink an LED on the shield base. Didn't do any testing beyond that after hitting the exception. Also, the exception occurs regardless if anything is wired to the pins on the shield base.

Here's my code:

NetduinoGo.ShieldBase shieldBase = new NetduinoGo.ShieldBase(GoSockets.Socket5);
      // open serial port
      SerialPort serial = new SerialPort(shieldBase.SerialPorts.COM2, 9600, Parity.None, 8, StopBits.One);

In Topic: Controlling several RGB LED strips

12 October 2012 - 12:02 PM

Matt -

I did a little googling on PWM signal distance limitations. Check out this thread. To quote "Rule of thumb for a typical logic signal is 12-18 inches..." I'm no expert on transmission line theory, but I'm 99% sure you won't be able to run long wires "through the ceiling", or anywhere else over two feet away, for a PWM signal. Your desktop lights are going to have to be smart :)

In Topic: Controlling several RGB LED strips

12 October 2012 - 01:33 AM

Thanks for the info ransoMhall, that goes a long way to helping out!

I definitely have to use several shorter LED strips, the strips are to be mounted into the blocks and the blocks placed next to each person's desk. Having one long continuous strip won't work here sadly! I'll go for the 5V variant, I think, however powerign them separately isn't a bad idea. How would I go about achieving this?

The IO60P16 Module actually doesn't look like too much of a bad option. It's overkill, sure, but not too expensive and probably does what I need it to. I can see there's an arrangement of PWM outputs on this module in sets of three: are each of these individually controllable (i.e. can I control 16 different RGB LED strips with this board, or just five)? Can I use more than one module per Netduino Go?

Again, thanks for your help, this is easily the biggest project I've done on either an Arduino or a Netduino, the advise is much appreciated!


I may be confused. Is each block going to have its own controller (Go or other)? If not, you would have an awful lot of wiring going from a single micro to blocks on many desks. There are distance limitations for low power signals like those used to power LED strips, not to mention it would probably be impractical to run wires all over the place.

On power, you can power the micro and strip separately as long as they share ground.

Gadgeteer modules will not yet run on a Go. There is an adapter in the works, but it is not released yet (November maybe?). See other posts on this forum for details. I'm not sure if you could use more than one IO60P16 on a Go adapter. In theory, as long as there is more than on I2C socket type on the adapter, the answer is yes, but that is a lot of "theory" that needs to be tested.

You should be able to control 16 PWM signals from the IO60P16 module.

Start by picking the LED strip you are going to use, THEN design your project around it. It will help immensely to have a datasheet in front of you when pondering your design and asking Qs here.

In Topic: Controlling several RGB LED strips

11 October 2012 - 12:38 PM

Matt -

Sounds like a fun project! I've been playing with LEDS on Arduino and NETMF boards for several years and never get tired of the fun.

So... what kind of LED strips are you planning to use? The answer to this will drive the answers to most of your questions.

On LED voltages - strips generally come in two flavors: 5V an 12V. While you *can* power the 5V version directly from a microcontroller, you will quickly use up all the current the board has to offer with anything over a couple of meters. Again, this depends on the strip specs. The best (and safest) bet is to design your circuit assuming the LEDs are separately powered.

It sounds like you are assuming the strips will be in parallel, with one PWM channel per strip. There are not eight PWM channels on any of the boards you mention. The Netduino has 4, so you would need two. You would have to find an external chip or board that has enough PWMs (like this which is overkill IMO).

Take a look at the strips that use LDP8806 or WS2801 controller ICs. These are pricier, but let you control each LED individually, so you could have all eight office monitors in series from *one* SPI channel (hence controlled from one micro). These strips also can be cut at intervals, so you can space out your blocks. This assumes you don't mind having all eight wired together in series.

There are various controller boards out there specifically designed to drive LED strips. You may be able to find one that suits your needs which itself can be controlled via UART, SPI, or I2C. The one I use is made for one long strip, however, and not many short strips. It handles the power nicely and can be controlled via plain old serial COM.

I suggest going with one long strip with embedded ICs where you can control each LED. This will keep the design simpler. If you want to stick with the parallel block arrangement, look for a PWM controller board that can itself be controlled from a Netduino or other micro. The final design will ultimately depend on how these blocks will be physically arranged.

Have fun and don't be shy asking lots of questions here.

In Topic: Flashing Go Modules using ST Microelectronics’ Flash Loader Demonstrator

11 October 2012 - 12:02 AM

Fabien - thanks for the video. I used the STM32ReflashApp to update the ShieldBase recently without issue, but am glad to know about the Go firmware corruption problem. I like your "direct" method better.

For those of you looking for a single row breadboard breakout for the Go socket, I sell them for $5 assembled (and $3.50 for just the PCB) here, if you can stand the Gadgeteer logo ;) The pinout is the same. They are also OSHW with Eagle design files available on the linked page, if you want to have some fabbed (oshpark is high quality and very reasonable).

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