Kermit's Content

#27846 Many many PWMs

Posted by Kermit on 21 April 2012 - 08:01 PM in General Discussion

I thank you all for your input, but I'm living in Italy, and I'm seeing that I cannot find all over Europe someone who sells the shields you talked about in the previous messages: I can barely find the (naked) TLC5940 chip, I think I'll have to build the circuits myself... :-( Andrea

#27845 How to drive train models

Posted by Kermit on 21 April 2012 - 07:57 PM in General Discussion

...you drilling with your LEGS??? :-) Andrea

#27831 How to drive train models

Posted by Kermit on 21 April 2012 - 05:40 PM in General Discussion

PWMs
Ok, since I had started (and quickly closed!) a related thread, I consider the problem of the many PWMs closed (with just another order for new components!!! :-)))
Andrea

#27812 Many many PWMs

Posted by Kermit on 21 April 2012 - 12:26 PM in General Discussion

PWM IC:
http://www.sparkfun.com/products/10136

On a breakout board:
http://www.sparkfun.com/products/10615

...ehm... I don't know how to tell it in English, but right now I have a big big red face... :-(
Andrea

#27805 Many many PWMs

Posted by Kermit on 21 April 2012 - 11:09 AM in General Discussion

Since my other thread is getting long (Train models), I start here a new thread for a subproblem: how to drive, for example, 20 PWM signals from a single Netduino.
Yes, the first straight answer could be to buy more Netduinos, but it's not only a cost problem: then I'd have to sync all together, that would be another big problem!
What I'm thinking about, is there some solution where I first select an 'address' (to be considered in a wider sense...), and then I set a duty cycle? The 'subcircuit' (or something like that) should retain that value, be self-powered, and going on supplying the exact pulse until maybe I re-select the same 'address', and put out a new value.
The first idea coming to my mind is to use many shift register chained in SPI, where, using the output pins of each shift register, put out a 'value' to feed to something else to be used as a PWM source (and obviously I don't know how to create such a thing...).
I googled everywhere, but I couldn't find any good start, so I'm really at zero! :-(
Is there anyone pointing me to a good direction?
Thanks in advance
Andrea

#27796 How to drive train models

Posted by Kermit on 21 April 2012 - 08:48 AM in General Discussion

Did you spot the problem? - The Netduino only has 4 PWM outputs, so you might need to use a PWM shield to get enough PWM outputs for your 5 sets of rails.

Hi, Paul, since my first tests are ok, I'm now thinking again to the problem of loco controlling.
You told me about a pwm shield, I saw it, and I think it can be a good (and cheap!) solution. What I cannot understand is that to me it seems that I'm using in the shield the same PWM pins that I have on the Netduino, so I cannot reach the five PWM that I need.
Moreover, if I understand it well, I need TWO PWM pins to control a single loco? Forward/reverse? Please, can you give me some hint?
Andrea

#27752 How to drive train models

Posted by Kermit on 20 April 2012 - 09:10 PM in General Discussion

Yes, I had already googled to find the same results (am I entitled to be called 'a wise man', too? :-)). What I was pointing out was that even if this is not the best cable I can use (it's another order of mine, still waiting for 100 meters of CAT5E FTP), I could easily obtain perfect results on a 5 meters cable (and at 1Mhz!), that, for what I was told here, wasn't expected... Andrea

#27722 How to drive train models

Posted by Kermit on 20 April 2012 - 03:12 PM in General Discussion

Ok, I have still another order to do, for the relays! :-))) But, what's more interesting, today, is that I tried to use SPI on a long cable, so I create a test environment: My Netduino Plus, with two cables connected: one with two wires for +3.3VDC and Ground, and the other for the SPI signals (three wires used out of four). The cable was 5 meters long (16 feet?): I cheated a little bit, because I didn't have two different cables at hand, so I kept Netduino and breadbord very close each other, and used a normal short cable for +3.3 and ground, BUT I used the 5-meters long cable for the SPI. I started with a very conservative 1Khz setup (only because I couldn't make still less! :-)), and I found the signals went up and down without a single problem (leds attached, with fixed on/off time length). Then I went up until I saw that even at 1Mhz, the behaviour was still perfect, at least for what I could see personally on the leds (that's what's important to me). I don't know if at low level there are any problems, in syncing or what, and I know (thanks to Mario) that the main problem is not the frequency, but the wave shape: still, I'm very happy for the result, just for my start in this new (for me) field. Is there anyone that can tell me if I'm oversimplifying the problem? I know that I'll have to use it in a 'noisy' environment, but it looks like the start is encouraging! By the way, the cable I used for the SPI is a shielded telephone cable, with the mark on it: 'SYT PLUS 1 NUM 2X2XAWG24 A10-41/04', if someone knows what it can mean. I can only understand that they are 4 wires (NOT twisted, moreover) of type AWG24, plus another one, without any plastic around it. As always, I would like some comment from who knows way much more than me... :-) Andrea

#27645 How to drive train models

Posted by Kermit on 19 April 2012 - 02:20 PM in General Discussion

Hi to all. I have all the pieces, now: italian mail system is not so fast, but at least I received everything, so I can start to make my tests (I have some test loco, rail exchange, power supply, courtesy of my friend, too...). The first test (Mario's suggestion) has been very fast: I tried a 9V DC battery trying to move the rail exchange, but I only hear a little click, and nothing moves. I tried every combination, but nothing. So it looks like I have to stick with AC: on the power supply, I see 16V, 8VA (so I suppose 0.5A :-)). With this low current, couldn't I use a 'normal' BC557 to act as a switch? Or the fact that it's AC blocks this possibility? I would like to get an advice, before burning something... :-) If not, what kind of relay do I have to look for? Thanks as always from a rainy Italy... Andrea

#26795 How to drive train models

Posted by Kermit on 09 April 2012 - 05:57 PM in General Discussion

...and for anyone interested in Netduino AND chocolate, here it goes...
http://www.baciperug...na_history.html
But don'ask for more boxes, I'll send one only to Paul! :-)
Andrea

#26794 How to drive train models

Posted by Kermit on 09 April 2012 - 05:54 PM in General Discussion

No, no trains, but here in Italy we make them with real little rivers, moving puppets, dawn-sunset lights... and so on! :-) Ok, since I've said it, I'll have to arrange a box of Baci's for you! :-) Andrea

#26788 How to drive train models

Posted by Kermit on 09 April 2012 - 04:41 PM in General Discussion

It's always a pleasure, to hear from you, Paul! (do they sell Perugina's Baci - Kisses, in Reading? Ever tried one? :-)) I thought about fiber-optic cable, too, but never talked about it, because maybe it's a little bit James Bond-ish... :-) Yes, the only thing is trying, and it's because of this that I already had issued another order!!! :-) When I have everything, I will not have enough time to test everything! :-) Andrea P.S.: next in list would be the automation of the 'crib' in my church, for Christmas... (I don't know if 'crib' is the righe word, I found it with Google Translate)

#26785 How to drive train models

Posted by Kermit on 09 April 2012 - 03:38 PM in General Discussion

As always, thank you, Paul! (but your advice on chocolate is a bit too late... You know, I live close to Perugia, that's a chocolate city!!! ;-))
Coming to the problem, yes, I read about not too long distances with I2C, but then I also read documents like this:
http://www.esacademy...ns/i2c-faq.html
or this:
http://ics.nxp.com/products/i2chubs/
where is explicitly said about hundreds of meters or even kilometers...
Do you think they are believable, or is there something hidden? :-)
Andrea

#26776 How to drive train models

Posted by Kermit on 09 April 2012 - 02:01 PM in General Discussion

...I'm still studying for the first problem of this thread, that, I recall, is about controlling some I/O devices (typically LEDS) from a distance of about 5-10 meters.
I still didn't try any of the solutions already kindly proposed (for example, direct SPI connection with a 74HC595): I made e new order of components, but they failed to arrive (it's Easter time! :-)).
So I went on looking at ways to solve *easily* the problem (SPI is not certain to function over a distance...).
Now I spot this component: http://www.nxp.com/d...eet/PCF8575.pdf
...that for a newbie like me looks like what I'm looking for! May I control this component (many of them) directly from a Netduino?
Thanks again to whoever will help me in choosing the solution.
Andrea

#26590 How to drive train models

Posted by Kermit on 05 April 2012 - 09:41 PM in General Discussion

In fact I'm thinking to go down the data rate to minimum speeds... I don't think this can be a problem, with what I need... If this helps me a lot, do you think the solution can become feasible again? Yes, you are right... the only thing is to make some tests... Andrea

#26570 How to drive train models

Posted by Kermit on 05 April 2012 - 06:54 PM in General Discussion

...and I would add this document, too...
http://www.ti.com/li...441/slyt441.pdf
It looks interesting.
Andrea

#26564 How to drive train models

Posted by Kermit on 05 April 2012 - 06:01 PM in General Discussion

Mario,
can you give a look at this thread?
http://www.avrfreaks...ewtopic&t=60979
It looks like leveraging low data frequencies, some result can be obtained.
I cannot understand the technical details, but someone agrees, some other not! :-)
Andrea

#26563 How to drive train models

Posted by Kermit on 05 April 2012 - 05:41 PM in General Discussion

...oh, and for now, I didn't think at all to locos and motors... we will see: I'm sorry, but not being an expert, I prefer to think problem by problem... Andrea

#26562 How to drive train models

Posted by Kermit on 05 April 2012 - 05:40 PM in General Discussion

No, actually, we are more on the 50 & 50 side (50 leds and small things, plus 25 rail exchanges), but my friend is stuck with complexity: he would like to add things, but decided to stop and think what we can do... Anyway, from what you are telling me, the problem is more on distances, than quantity... Andrea

#26521 How to drive train models

Posted by Kermit on 05 April 2012 - 12:22 PM in General Discussion

:-) Yes, I think that Monica Bellucci is our national monument! :-)))
Apart from this, I don't want to throw anything away, I'm not that kind of guy... only, I'll have to study much more, and understand how I can solve the problem: challenges are made to be solved! :-)
Posted Image

Done with Paint, here is an image of how the model is: 10mx4m, there are a lot of different devices to control (the image cannot convey how many different, and small, electric devices there are), and my friend kept adding every single device, linking cables from any single device to the control center.
So, other than the wires, other problems are all the power adapters (from 220VAC to 9V, to 12V, to 6V, to 16VAC..., many for each voltage), buttons, pulse buttons...
And he would like to go on adding other devices, so reordering things, finding a different solution than the brute force, is becoming NOT an option!
I was pretty sure that I could send signals over a 10meters span, it didn't look a so great distance, but I believe in you, so I only have to explore other possibile solutions!
Andrea

#26512 How to drive train models

Posted by Kermit on 05 April 2012 - 09:42 AM in General Discussion

Oh, I didn't think that a hobby problem could become so complex (and interesting! :-)). Yes, the budget is important, I think not only for me, but in general for any hobbist (but it depends on what we consider a budget; I think a budget is what an average person can spend thinking it will *NOT* have a cash return selling solutions): good solutions are the cheap ones, otherwise we step into professional solutions (that are not for me, anyway, since I am a software programmer!). So, thanks to anybody for any contribution, every single concept is really interesting, even if I thought this was the *easy* one, and it became the *worst*: the sad conclusion is that if this is the situation, it is difficult to imagine Netduino used in real solution different from toys/educational kits. When I see here people trying to make home automation, don't they crash in problems like this??? My thanks become larger and larger, I'm learning really a lot of things! ...and the dinner invitation is for Mario too (maybe it's easier, for him!) Andrea

#26480 How to drive train models

Posted by Kermit on 04 April 2012 - 10:11 PM in General Discussion

Ok, Paul, I must be crazy! :-( Reading and googleing everywhere, I didn't remember that you already gave me the shift register solution: you are very sharp too, since you point out (correctly) that the wires are not surely three, but this is not a problem, since one only cable going round is surely much simpler than things now. I'm not an expert in electronics, so I cannot understand the capacitor thing (to avoid 'rumors'): but with your hint I'll try to find more info about it. I owe you a dinner, so if you ever come to Italy, I'll really be happy to have you in my house! :-) Andrea

#26472 How to drive train models

Posted by Kermit on 04 April 2012 - 08:39 PM in General Discussion

Oh, no... the beauty of the system is that some of the trains are *really* old, so are most of the railways: so the project is to add control, but leaving all the (physical) model as is... Digital trains are not an option! Thanks anyway for the idea! Andrea

#26471 How to drive train models

Posted by Kermit on 04 April 2012 - 08:37 PM in General Discussion

...maybe because I don't even know what it is... :-) I'm going to learn another thing... googleing right now! :-) Andrea

#26423 How to drive train models

Posted by Kermit on 04 April 2012 - 02:48 PM in General Discussion

I'm here again! :-)
After reading books, googling around, I decided to start from the first problem (probably the easy one): controlling a lot of leds or similar devices on a wide surface (10 meters x 4 meters). Since actually there are really a lot of wires and cables, I think that using shift registers chain-linked each other and put in smart positions can save a lot of these cables.
Posted Image

This simple drawing can give the idea, I hope: the shift registers act as local 'pits' where to connect leds to, so I need only a three wires cable going all around, and the local (short) connection to peripherals.
Moreover, I think that netduino cannot power everything, so I'll have to add a power line going all around, and transistors to act as switches to activate the single peripheral, when put on.
It looks like it can become all very clean and simple, if this is a feasible solution...
Before starting testing, I would like some good advice, if possible: thanks in advance, as always!
Andrea

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