hanzibal's Content

#55428 .NET Fart Detector

Posted by hanzibal on 16 January 2014 - 05:41 PM in Project Showcase

I really can't believe I'm the only one fascinated by this, come on folks - admit that it's really cool or at least very funny!

#55432 .NET Fart Detector

Posted by hanzibal on 17 January 2014 - 01:47 AM in Project Showcase

Oh really, come on!

#55289 .NET Fart Detector

Posted by hanzibal on 10 January 2014 - 09:04 PM in Project Showcase

Ha, ha - that is just hilariously awseome!

As a child, I actually dreamt of creating a fart detector in order to answer the inevitable question "who was that?" and now, some 30 years later its finally here - your are a true genius!

EDIT: It's mostly methane is it not?

#49966 3x4 Matrix Keypad bounce problem

Posted by hanzibal on 25 May 2013 - 08:31 PM in Netduino 2 (and Netduino 1)

I'd expect time to be zero when the board starts up since there's no RTC on board, or is there? After startup, clock should start ticking of course. Would that explain the phenomena you're seeing? EDIT: What is the initial value of the ButtonLastPushed variable? I guess it should be DateTime.MinValue.

#49975 3x4 Matrix Keypad bounce problem

Posted by hanzibal on 26 May 2013 - 06:30 AM in Netduino 2 (and Netduino 1)

I really doubt it's the keypad, I think you should try setting a few breakpoints in select places of the Toolbox.NETMF.Hardware.MatrixKeyPad driver code and find out where that zero originates from. There could be a bug in there or perhaps something resulting from incorrect wiring.

#49971 3x4 Matrix Keypad bounce problem

Posted by hanzibal on 25 May 2013 - 09:52 PM in Netduino 2 (and Netduino 1)

Ok, that is truly strange. What if you just assign a variable DateTime.Now, does that produce anything other than zero? If not, could be hardware problems but one should think more stuff would also not work then so I assume you get a decent value and that would leave a firmware upgrade or you've teied that already perhaps? I don't know the differences, if any, between the N2 and NP2 with respect to such an issue, I'd suspect there's none.

#50857 a new i/o pin

Posted by hanzibal on 27 June 2013 - 06:30 AM in Netduino Mini

Sounds like you got it from a secret place ;-)

#50776 a new i/o pin

Posted by hanzibal on 24 June 2013 - 10:58 PM in Netduino Mini

Interesting.... Getting +/-6V could be useful in some cases. Any idea of how much it can source? I would guess about half as much as any other regular pin since those are 3V3.

#50151 Analog.ReadRaw unhandled exception in SecretLabs.NETFM

Posted by hanzibal on 31 May 2013 - 07:56 PM in Netduino Plus 2 (and Netduino Plus 1)

Hi, That "first chance" is from an exception being caught in a try...catch and the second is an exception (the same?) not being caught. I suppose the error is what it is said to be, e.g. an object that unexpectedly has a value of null. Since the code has run for quite a while and the exception looks not to originate from your own code, my guess would be that it is due to unsufficient memory available or something else that builds up over time. I would think its hard for anyone to say much more about it having not seen your code.

#50492 Another Newbie Steps into the Arena

Posted by hanzibal on 14 June 2013 - 08:51 PM in General Discussion

Halogen light contains lots of IR so, like Paul said, watch out if the room is heavily lit and with what. I made something similar with a electrical model car race track where I could use photointerrupters since those cars have small "fins" sticking down a slot in the middle of each track. I suppose you need to time each car separately and not just the winner which makes it more difficult. Another idea might be to use micro switches buried in each track at the finish line. The switches would have to be fitted with with fairly long arms to make them easy enough for cars to lever as the they rush by barely touching the switches. This might be the easiest way to do it.

#51705 Anyone tried XMarine?

Posted by hanzibal on 26 July 2013 - 10:35 AM in General Discussion

This is not directly related but looks an interesting way to build smartphone apps for interfacing with your Netduino, for example via sockets over a network.

As I understand, XMarine would enable you to use Visual Studio for writing apps for both Android and iOS devices.

http://xamarin.com/

To me it sounds very cool. Has anyone of you guys tried it?

#50815 Anyone using WCF?

Posted by hanzibal on 25 June 2013 - 10:06 PM in Netduino Plus 2 (and Netduino Plus 1)

If you only want to send simple messages back and forth, you could always use sockets but perhaps that's a bit too simple plus you'd have to do any and all marshalling by yourself if you plan to transfer more complex structures. A web server doesn't have to be all that "full" either, you could just parse out the query string from the headers, perform the corresponding operation(s) and return a string like "OK" or whatever. I don't know if the HttpListener class et al is available but if so, it would make it very easy to implement a light weight web server. You could do many of the requests using AJAX and thus do the request/response parsing in client side javascript while displaying a fancy main page with the buttons and controls and what have you. Maybe throw in some JSON to get a little more structure in the server (device) responses. Now, I don't really know WCF or its benefits and maybe you have already considered the above.

#52255 Audio sampling

Posted by hanzibal on 21 August 2013 - 11:26 AM in General Discussion

Hi!

I think max sampling rate is 2Ms/second (see datasheet for the microcontroller) but you won't come anywhere near that rate or probably even 44.1kHz in managed code (plus for stereo you would need 2 channels = half the rate with a single multichannel ADC).

The Netduino ADC is only 10 or 12 bit (depending on micro) and meant for reading sensors and such much rather than sampling audio signals. F�r CD quality, even native code won't help.

I suggest you look at some external ADC board with more suitable specs, possibly something with a DSP onboard. Also bear in mind you need to handle the data stream which would be 2 * 16 * 44100 = 1,4Mbit/second for CD quality audio so if you're looking to do real time DSP, you're in for a real challenge.

You might want to look at the VS1053b from VLSI, it's an primarily a MP3 decoder but it can sample CD quality audio producing an MP3 (or Ogg Vorbis) encoded audio stream for you. The chip also has a few simple DSP effects.

You should probably check out www.minidsp.com

Sorry if I sound negative but I really don't think Netduino is you best choice for the task.

Good luck!

#52306 Audio sampling

Posted by hanzibal on 23 August 2013 - 06:47 PM in General Discussion

...However, I am more concerned about how things work if I wanted to get the high sampling rate you mentioned done in native code, while at the same time running managed code. How does that all work? It has been a long time since I did low level programming. Is it possible to have the native code reading the samples, by interrupts, using a timer, while at the same time feeding the results of this to a parallel executing managed thread?

AFAIK, there's no ready made API for doing this, instead you need to modify the Netduino firmware to implement the functionality you need. This means setting up a C language tool chain for the micro in question, creating your own specialized branch of tinyCLR and thereby diverging and detaching from the Netduino main track. I haven't done this myself but many others have, so you can search the forum for guides on how to proceed along this path.

Just thought I'd post this here in case anyone ends up searching for the same stuff: http://www.iar.com/G...4_MCU_part1.pdf Cortex M4 has DSP instruction set and there are libraries available. Also - I found this: http://www.micromint...bambino200.html It is a .NET Gadgeteer compatible board with a multi core ARM Cortex .

That Bambino board looks interesting but for some reason I personally don't care much for gadgeteer boards and therefore don't know much about it. Ah, so there's a set of dedicated DSP instructions in M4, I was unaware of that. Texas are quite knowledgable within digital audio in general (especially since they aquired Burr-Brown) and the field of DSP in particular where they have a broad range of processors: http://www.ti.com/ls...AliasId=1200327 Did you have a look at MiniDSP.com? I really think that's more in line of what you are looking for. Please don't let this discourage you from getting a Netduino since I'm sure it would be a great tool for you to learn more of embedded programming and for interfacing with the other h/w parts that you will need. Please explain a little more of your goals and what you are hoping to achieve and I'm sure someone else here will be able to help you further.

#56671 Automated Urban Garden

Posted by hanzibal on 06 March 2014 - 11:49 AM in Project Showcase

Great project!

If you need more sensors, you could try interfacing the Parrot Flower Power:
http://www.parrot.com/flowerpower/en/

It would require a Bluetooth LE module and probably hacking their protocol. The flower power is a bit expensive but there's also the SensorTag from Texas which is not miles away (not a coinsidence):
http://www.ti.com/tool/cc2541dk-sensor

#56689 Automated Urban Garden

Posted by hanzibal on 07 March 2014 - 06:55 AM in Project Showcase

To think there are more than one manufacturer of such things, incredible really!

#56685 Automated Urban Garden

Posted by hanzibal on 06 March 2014 - 09:31 PM in Project Showcase

The SensorTag is just 25 dollars :-)

I got one, works perfecly with iOS devices but haven't got around getting a board for my Netduinos yet and turned out there's no BT LE drivers for my good old XP box (while as it is built into Win 7).

#50619 Best Hobby Oscilloscope

Posted by hanzibal on 18 June 2013 - 06:40 PM in General Discussion

Hi! The logic sniffer seems ok for UART and PWM analyzis but not as an oscilloscope: The analogue bandwidth of 200kHz is way too low and makes it pretty useless The display is tiny, mine is many times bigger and I still wish it was a lot bigger Buffers are very small, you can only see small fragments at a time I think these kind of gadgets are rather cool but don't qualifiy as oscilloscopes. It's like they thought "We got this tiny piece of hardware, let's see if we can make an oscilloscope out of it". It would be better if they'd thought "hey, let's design an oscilloscope and choose whatever hardware meets the requirements". No, I would put my money on something else.

#56349 bitwise comparison & IF condition

Posted by hanzibal on 24 February 2014 - 09:45 PM in General Discussion

That makes it compile but it's not quite the same thing, I'd say it translates into this:

if ((this_led_color & mask) != 0)       SDI.Write(true);else       SDI.Write(false);

Checking for equality to mask is no longer the same when mask has other than a single bit set.

#50929 BUILD 2013

Posted by hanzibal on 29 June 2013 - 12:00 PM in General Discussion

Ah yes, I've seen that shield. As you probably know, TI just released their CC2541 based BLE SensorTag - would it be possible to interface that using the Seed Studio BLE shield, one of those inexpensive dongles and (since you mentioned it) the Agent respectively?

#51013 BUILD 2013

Posted by hanzibal on 02 July 2013 - 09:09 AM in General Discussion

Ok, thanks!

#50871 BUILD 2013

Posted by hanzibal on 27 June 2013 - 11:27 AM in General Discussion

We built an app for Windows 8.1 (and Windows RT 8.1) using the new Bluetooth Smart (Low Energy) WinRT proximity APIs.

Chris, I'm very interested in BLE and have a few questions about your setup:

1. What shield/module/device have you hooked up to your NP2?

2. Is your Win8 machine equipped with built-in BLE or are you using a dongle, if so what dongle is that?

3. Do you know if the BLE APIs are available for other Windows versions than Win8?

Thanks!

#50969 BUILD 2013

Posted by hanzibal on 30 June 2013 - 08:26 PM in General Discussion

Yes, almost all BLE stuff I've seen is about talking to an iPhone but that does not really interest me plus I think wifi is better for that. I think the Agent and TI SensorTag combo would be much more interesting. Anyway, do you think one of these cheap BT 4.0 actually supports BLE and that it is able to talk to the Agent and/or the TI SensorTag over BLE? http://www.ebay.com/...=item3f1d09ffab Then of course, there's the API thing on a non-BLE equipped PC, I suppose that would be a show-stopper on Win XP.

#50824 Building a "valley detector"

Posted by hanzibal on 26 June 2013 - 05:43 AM in General Discussion

Ok, so basically you'll be using a software hp filter then, I suppose there are ready made functions for that in LabView but designing one in h/w is quite simple, basically you put a capacitor in series with a resistor to ground.

#50866 Building a "valley detector"

Posted by hanzibal on 27 June 2013 - 07:55 AM in General Discussion

Ok, there are of course much more sophisticated hp-filter designs that you could apply.