Studying better the datasheet, it looks like the E710 doesn't work on voltage, but in wave frequency, or something like that. I'm absolutely not expert: how can (if possible) the Netduino read such a signal? Thanks again Andrea

Is there anyone who knows if I can use it directly connected to the Netduino, or if I have to build some control circuit? Documentation at http://www.murata.co...og/pdf/s21e.pdf, the original Murata site, is of no use, or at least I think...
I tried to use the sample code I found at http://forums.netdui...h__1#entry17181 and http://forums.netdui...h__1#entry26933 thinking that it would be the same, or similar, but no way... :-(
Andrea

Hi to everybody. You know I'm a software guy, so, after having been helped so many times here, I try to give something back, even if I know I don't have the electronics expertize to be sure that I'm going in the right direction. So I invite you to read the readme, and, if you want, take a look at the code: I would like to receive some feedback by the experts, to understand if I'm going on the right direction, or if I'm missing something important, like performance, memory size, and I don't know what else... Andrea

So, the only way was connecting them via serial: specifically UART, using the RS-485 interface. That's still a very good solution, because it's the only answer to several constraints:

• simplicity (both hardware and software);
• cost effective (can be realized even on a half-Euro MCU);
• reliability (very high noise immunity);
• very long distance wiring (up to 1.2km);
• worldwide standard, thus thousands of sensors can be plugged without no effort;
• no need of permissions, instead of most radio-based systems (*).

Mario, here you said that we can realize an RS-485 connection with half-euro: could you elaborate on this, giving some advice, for us mere mortals? :-)
Thanks as usual from Città di Castello! :-)
Andrea

Mario, you are always way too kind and gentle, with an in-expert like me. As for Skype, I cannot use it for most of the day: moreover, I think that your expertize can be very useful to many people, so it would be wonderful if you could go on posting your thoughts here... Yes, the railroad project is still alive, and I added an animated nativity for the church (and we hope to do it for Christmas!), so, since my spare time is very little, too, I think that I can get both projects done for the end of the year (no hurry, on my side! :-)). You touch an important point on your last post: since I have a small consulting firm, specialized in Microsoft technologies (only software, at the moment), I would like to stress the functionalities of the Netduino to get the real grab on it. I've always been sure that only stretching the limits of things, I can deeply understanding potentialities of systems. In this sense, for me it's not too important to have a perfect solution, for the problem under investigation: what I care most is to get some real case experience on Netduino projects. That doesn't mean, of course, that in every situation I want absolutely use only a Netduino central unit, but that I want to do all I can to stay at least close to this (theoretical) solution. There is another reason, too... I don't know any other MCU, apart from the name 'arduino', so I should start again studying another platform... I don't think I have this will... :-) But, if you think it can be an interesting approach, could you point me to some inexpensive little board that I can link to the Netduino? Since I have a strong background in C/C++, I don't have any problem on these languages, but not worse! :-))) Can we make them talk and sync together without relevant problems? You are invaluable, Mario! Andrea

I'm really sorry to change cards again... :-) I tried to do my homework, during lunch :-), so I googled to try to understand what you could mean, and I find out that I can buy a complete arduino solution for as little as 6 euros (ATMega328 + spare parts), so, if this is programmable in C/C++ and has characteristics similar, more or less, to the netduino, this can be interesting for other eventual ideas where cost is an essential factor. So, now... ehm... if the satellites for the trains can be done using this solution, it would be even better; but now one IMPORTANT question comes to my mind: it's true that C#, visual studio, debugger, etc. etc., but what happens to my projects if ALSO the main unit becomes an arduino? Is it sort of a heretic question here??? :-) I feel that I can ask this here, since I've been many times certified professional with microsoft, certified partner with my (small) consulting firm, and grown up with Microsoft C/C++ 6.0 in DOS: is there (still) anyone remembering this last one? I kept its manuals in my library even now! :-))) Andrea

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

...mmmmm... I think I ended my apologies... what I can say is that now I think it's my Google, to be faulty... Thanks again Andrea

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

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

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

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

...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

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

Thanks very much, Paul, this is by far *much* more than what I hoped for. But I still have many questions, and I don't even hope for a further answer from you! :-) First of all, I need to clarify, for what I've seen of the model: rail exchange is done with a three-way pulse button, that closes a 16V AC circuit (this looks very strange to me! why not DC???) in one of two directions: you give an impulse up, for example, and the rail goes right, you give an impulse down, and you get the rail going left. There is an electromagnet calling the rail in the two directions. So the first problem is just this: googling around, I saw many people saying to *NOT* use DC to AC relay control, because of some coil *induction* effect (I don't know what this is, but they say that voltage can go really up for a few moments). Can you confirm that (I suppose because of the very small power) I will not have this kind of problem? The problem with the lights is much simpler: they are all very small LEDs, so the only problem, I think, is to use some sort of bus just to not have that many wires going all around. Actually for each LED there are two wires going back to the central control panel, and I think they are at least one hundred! A first approach could even be to use some other NetDuino in calculated places, to control local groups of leds, but then I have the problem of 'speaking' from a NetDuino to another, even if I think I can find documentation on this. The last problem, that in the first post I didn't mention, is to control train movement. Actually, since there are five distinct groups of binaries, my friend has five power supplies, but of a type I didn't know about. In Italy we have 220V AC, so this is the input, but then there are two outputs: one is the 16V AC to drive rail exchange, and one is the DC current to move trains, that can be altered with a gauge. Rotating this, you can even invert positive and negative, I suppose, because trains on the rails invert direction, and go faster or slower according to the level of rotation: so I suppose that this is some kind of potentiometer that can invert Voltage. My last question, at this point, is: may I think to replace this power supply with 'something' (what can it be?) that I can then control with software with a NetDuino? Right now, if you want to simulate the train going in station, you have to manually slow it with the gauge, but it would be fantastic to have some software algorithm at the press of a button, that slows the train until it stops! Too many problems? All of this looks very interesting, to me, even only to learn NetDuino programming *AND* basic electronics control (I already have bought a couple of books!). I am obviously available to share on this community all the details and the lessons learned! Thanks again. Andrea

Ok! :-) I realize, and I thank you, that you are all very kind. As for now, I think I have really *a lot* to study, and to test. My (little) spare time will go to this project, and I will report the progress here. I would have a lot more questions, but it would not be fair to ask everything, and not try and test, so I'll keep silent, now, and will start with the components I already ordered. Thanks to anyone, I'll let you know everything! Bye Andrea

No problem at all! Rather, thank you for your interest! Andrea

@MrSmoofy: No, digital solutions are not an option, we already talked about this previously in this thread. Thanks anyway. @PaulNewton: Paul, you are always the man! :-) Every message of yours gives me enough sparks to think about, and learning (or remembering) something interesting. But: since I already tested with PWM to change speed, and I saw that Voltage and Amperes are different at each speed, if I turn the wheel with my fingers, or with another motor, I can only get the voltage (and Amperes) for that speed. I will never know if the wheel is at its maximum speed, or to the maximum 'normal' speed that I have to run it to! The question came to my mind just because I tried many motors, at different input voltages, and different PWMs, but I cannot know if I'm going to burn them soon! It's not a great problem, I think that in another two weeks I'll have more than 100 of them, but just to know and learn... :-) Andrea

Hi to everybody. As a software programmer, I have a very small knowledge (and all theoretical!) about hardware at this level. So, my problem is: a friend of mine has a very large train model set (five groups of rails, 15 trains, 10 meters by 3), all handled in analogical (kilometers of wires! :-)). So I told him I could help, trying to use a netduino to handle all the problems, but now I realize I don't have the necessary experience. So, just to start, I focused the first two problems: - Rail exchange is handled by a 16V AC line: to move the rail in one of two positions, you have to close one of the two circuits (ground is common), and just with an impulse. Which kind of relay/transistor do I have to use? - Traffic lights, rail exchange, other lights: all need wires, and on a 10x3 meters set, there are a lot of them. I'm thinking to some sort of bus (I2C?) to minimize the number of wires, but then, again, which kind of solution may I imagine? Theoretically, I would like to have some sort of I/O controller with for example 16 pins, and being able to connect to it from a distance of 5 meters, or something like that; from there, I would have to use way less wires... Anyone so kind to give me at least the directions where to look for? Thanks in advance to anyone, and excuse my poor English... Andrea

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

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

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

Hi to everyone! :-) Here is the silly man again! :-))) Today's question is: since I asked my friends to find for me old car radios, printers, and whatever has a little motor in it, and now I have more than 30 small motors in my hands, all perfectly functioning (for my Christmas animated nativity), how can I find out what are their characteristics, first of all Voltage, since noone has anything written on it? Is it silly enough, for a question here? :-) Andrea

...long way for me, to get the grip on these things... Obviously I already knew of H-bridge, L293D and similar, but when trying REALLY to do things, you have to reelaborate what you know, and if you don't have experience, it's really a tough work... I hope to get more brilliant in the next times: I'm tired of my red faces!!! :-) What always puzzles me is how much you are approachable, and kind, to always answer my silly questions... Andrea

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