"The TMP35/TMP36/TMP37 are low voltage, precision centi-grade temperature sensors. They provide a voltage output that is linearly proportional to the Celsius (centigrade) temperature." This means the microcontroller has to have an analog input that can measure voltage - this feature is known as Analog to Digital Converter (ADC) and Netduino has its 10-bit ADC accessible via 8 pins labeled "Analog In 0 .. 7", you can use AnalogInput class and its Read() method to get the digital value of measured voltage on a certain pin (the value in range [0, 1023] represents voltage [0, Aref]). Hope this helps.

That's EXACTLY what I was looking for - gives me that specific context that ties the features of the chip to the functionality of the Netduino. I really appreciate this.

BTW, having looked at I2C a little more, I'd be interested in any Netduino-specific details on how I might use it (samples, etc).

Thanks.

Mark

Wikipedia can be a really great resource for understanding what different protocols mean, usually the articles are high level enough that most people with basic electronics knowledge can understand them and if you need more information you'd be able to go to google to look for specifics.

1 wire is just a protocol for systems to communicate, like i2c, CAN, SPI, TTL and RS232 among others are. 

Yes, I uses these resources :-) I've been looking at a number of places but, again, it's the Netduino context I am looking for. By way of example, the DS18S20 is, I am told, not considered suitable for the Netduino. The fact that it uses 1 Wire (and the Netduino - without firmware updates - doesn't support this) seems to be the data point that I should be looking for. OK, I'll buy that :-)

But what about the two that have been suggested (the LM50 and the TMP36)? As far as I can tell, the data sheets don't have any references to I2C or CAN or SPI or TTL, etc, etc. So, it doesn't seem to be as structured as looking for a protocol that Netduino uses and seeing if I can find it in the datasheet. If I look at the TMP36 datasheet, for example, what is it about that which tells you this could work on a Netduino. Also, does the fact that a chip (like the DS18S20) supports 1 Wire and the Netduino doesn't simply mean that there's no way to get it to work? Or is 1 Wire just one option, but not a requirement?

And finally, let's take the TMP36 example again. If it's deemed feasible for the Netduino I'm still not sure how I'd actually use it. The 1 Wire approach seems to require more of a formalized "command protocol". I don't see such an approach with the TMP36. Does this just mean that I merely respond to pin changes (high/low) with this and don't use commands?

Thanks.

Mark

Actually, there's firmware (by CW2) for the Netduino that supports onewire. And SL is rolling his code into the main codebase I believe.

I guess I'm still not getting exactly what 1 Wire actually is. Is it a protocol that defines the physical characteristics of the protocol (I see references to pulse duration and amplitude, for example). Or is it more at the application layer (I see comments about commands that I can send).

Anyway, that's more a curiosity. At this stage I'm interested in what is available to me with the default Netduino firmware (I'll think about upgrading at some later stage). Let's say I am looking for a temperature sensor. What exactly is it in a datasheet that will leave me able to state whether I can get this working on the Netduino? I'm not so much interested in a specific recommendation for a sensor here (although the pointers were appreciated). I'm just trying to get my head around the characteristics I'd need to look for when hunting down a chip/solution I might use in my project. For example, with the two suggested already other than being told that they work I don't know how to check that for myself.

BTW, it could be that my understanding will be clearer if I understand what I2C or UARTs are and how they are used. I asked about this last week but didn't really get any pointers to stuff I can read as to actually use these ports.

Thanks again.

Mark

Unfortunately, Netduino doesn't appear to support 1 Wire, so you'd want to look for an i2c, spi or analogue output temperature sensor.

Something like a LM60 from National or a TMP36 from Analog are examples of analogue output sensors.

Thank you, Mark. Your message is very helpful because it starts to give me a sense of what I am looking for in a chip. So, it seems that I could use the chip I mention if my microprocessor I had came with "1 Wire" support. Is that something that would be flagged as a feature of a microprocessor?

Similarly, what clues might I look for when I review the datasheet for, say, the LM60 or the TMP36. I look at those and I don't see anything that leaps out at me as "Yes - Netduino supports that!!!". I guess I am trying to figure out what the relevant standards/features that are important as I search around for a solution. Is it maybe the fact that the chips you mention seem "passive" in nature, meaning they just emit their information on certain pins and, providing I can connect to and interpret the high/low values from the Netduino then I am OK (as opposed to the device I mentioned which seems to have a full-fledged "command interface").

Thanks again.

Mark

I am having a blast getting familiar with my Netduino (and, in fact, refreshing my memory of electronics - so lots to learn). One of the biggest challenges I have is getting some context for what is realistically in scope for what I can do with the Netduino (and what I can not). Let me take an example. Take a look at this digital thermometer (DS18S20). http://datasheets.ma...ds/DS18S20.pdf. I like the idea of being able to (eventually) hunt down chips like this and integrate them into solutions. But I have no idea if I am barking up the wrong tree. For example, the chip has a defined set of command (initialization, reset, read, search, etc, etc). What pins would I hook up (on the Netduino)? And how do I send command to a device like this. The datasheet has detailed information on the initialization timing - the pulse levels, durations, etc, etc. Are such things controllable from the Netduino and, if so, through what pins/features would I do this? I am not so much asking about this particular device (although I am actually interested in this). Rather, I'm trying to understand if this is the type of device that I can consider down the road when I learn more about the techniques available to me through the Netduino (hardware and software). Thanks. Mark

Editing my own comment in response to Davids's kind gesture. Back to Secret Labs... Mark

.

Thanks everyone (especially Hari, for posting "evidence" in the form of the video :-)). I am pretty sure my multitester is good since I have never had a reading issue with it elsewhere. However, I subsequently tried (having rebuild the circuit, small as it is) on Sunday and I got a 3.3V reading, if I recall. It could be that I messed up somewhere, although I did double check at the time since I was confused. Still a bit confused. Anyway, I'll check it again at some point. Thanks again. Mark

Hi Mark,

What are you using for your ground reference? How are you powering your Netduino?

Chris

Hi Chris,

I am powering with a USB connection to my PC. Should that not get me 5V? I am just using the GRN pin for the ground reference.

Thanks.

Mark

Hi Mark,

If you are pushing a PWM freq over pin 13, you may not see an accurate voltage when reading with a multimeter. Otherwise, I don't know why.

Thanks again. The only line of code I have releted to this pin is:

OutputPort ledcheck = new OutputPort(Pins.GPIO_PIN_D13, true);

So, a bit confused about why I see only 2.4 volts (on this or any pin, for that matter).

Thanks.

Mark

Thank you, Chris - much appreciated. Some follow up questions. Any thoughts on why I am only seeing about 2.5V on pin 13? I haven't seen above that yet on any pin. Regarding the use of a motor, if I plug the motor into the 3.3v pin it works fine. If the digital pins are 3.3V (or at least to be - see above) what is the issue with using the motor off a digital pin? Beyond that, if I want to embed some logic for when the motor kicks in within my C# code (based on some sensor, for example), what is the preferred approach for hooking up the motor so that a) I can turn it on and off and I can also control the speed? Told you I'm a newbie :-) Thanks. Mark

I am trying to come to terms with the various pins on my spanking brand new Netduino. Some of these are probably basic electronics page (I am a software chap, with limited hardware experience).

• What is the maximum output on the digital I/O pins? I see 3.3V mentioned on the specs page but when I take a voltage I see no more than about 2.5V
• What is the high voltage for a digital pin supposed to be? This is where I get the 2.5V from - I put an LED in and ensure that pin 13 is on and read 13.
• am I right in saying that ALL the pins can be used as "simple" on/off pins (programmed with OutputPin) but some of the pinds offer additional capabailities (such as PWM on pins 5,6,9 and 10)?
• What is a typical application for a UART pin?
• Same question for SPI MOSI - in what scenarios might I use these?
• Same for I2C
• Why no analog out pins? For variable output like a motor where I might want to vary the speed that seems like a problem. Or am I supposed to use PWM in such a situation?

Thanks.

Mark

Well, after a while waiting (including a UPS train derailment :-)), I finally got my Netduino today. All worked exactly as planned and within 15 minutes I'd run the blinking light demo and the event handler. All pretty simple. And now I have some questions... I purchased an AdaFruit Protoshield and that's all build and piggybacking my Netduino. What's not clear to me is how the various buttons on the shield relate to the Netduino. For example, I have two LEDs on the protoshield and two buttons. How are these addressable through code (given that the Netduino only has one of each)? How does the Port.ResisterMode work? Does this imply that I can turn on and off a resister associated with each pin? And if so, what resistence is involved? I'm not clear on the various voltages available to me between the Netduino and the protoshield and what pins use what voltage. The analog pins use 3.3V input right? Anything above that can do damage? What I'd like to do as a next step is control a 5v motor, attached to the shield, and have its speed adjusted with a photoresister. Pretty basic, eh? :-) I'm not clear on how/where I'd hook up the motor to the shield (which pins) and also where the photresistor fits into the picture (on the shield in series with the motor, presumably, but what voltages should I use)? I like the event handler approach (as opposed to a while(true) loop. As a curiosity I'm wondering of there's any way to have the photoresister trigger the motor on and off only when it reaches a certain light level (= resistance) and if this can be done with event handlers. I'd like to detect this in software and take "some action" based on the resistence (like start the motor). How would I go about that without the while(true) loop? I'm really looking forward to getting into this. Thanks. Mark

I would have said force sensors would be the obvious choice here.. as they are basically paper thin, and weight nothing. Just calibrate them to fire over a certain 'pressure' of stroke.

See: http://www.google.ch... resistor (FSR)

Thank you. Yes, that looks like a reasonable approach to me. What isn't so clear to me is where the logic resides to define a "keypress". This question will expose my lack of experience in this area (and, as I write, my lack of Netduino, which should be here by the end of the week!).

As I understand, the force resistor will basically return a value (indirectly, at least). I presumably need to define the minimum force (resistance) to start the "click" and the maximum for when it ends. Is this the sort of logic I define myself in my own code (and what sort of event do I use to identify when the method I wrote should be checked)? Or can I define some sort of event handler that detects when the resistance changes (does it change by tiny amounts without any actual pressing or will it be at a "known" resistance unless someone actually presses)?

Or - he said wishfully - does the .Net Framework provide some sort of abstraction to all this so that I can identify the resister as my "key" and just receive key-up and key-down like events?

Thanks again.

Mark

That's a great idea (on the introductory guide), Mark.

We'll post more tutorial videos soon as well (on Analog Inputs and on some debug features next).

Chris

Chris,

I understand that the video's take a while to design/record/post but in the meanwhile is there any thoughts about an intial page/document/FAQ that gets newbies to the point where they can do something useful, without falling over at an initial hurdle? I am not talking anything fancy - just a place to document "stuff" that might catch folks out. By way of example, this thread has some interesting comments about pin numbers that - I suspect - would have taken me a while to work out (yet, presumably, are important to anyone looking to read digital inputs): http://forums.netdui...blinking-leds/.

Obviously these forums are great. But a lot of the aggregated knowledge is spread across all sorts of threads (I just stumbled across the one above).

Anyway, interested to know if something might be in the works (a FAQ, split into sections, seems like the best approach).

Thanks.

Mark

Frank, I'd consider myself a newbie (in terms of playing around with the "physical computing" element). But, aside from that, our backgrounds are similar - I had a Commodore Pet, used dBase II (my university thesis used it), I programmed in 6502 and eventually moved on to VS 200* and C# (a good deal of my play time has been in C#/ASP.Net). Any, like you, my Netduino is on it's way :-) One difference is that I don't have an Arduino. So, my learning curve is going to be an interesting one. The one thing that worries me a bit if my life-long tendency (and a sad one!) to move from hobby to hobby! I hope this will stick but I am pretty sure a really important part be finding a project that really grabs my interest. That won't be for a while since I have so much to learn (the basics) but, beyond that, I know I'll need a real focus eventually. So, I'm regularly thinking about that key project that will challenge me and interest me. I'll be watching your experiences with interest. Thanks. Mark

I would say, the biggest downer I have with the Netduino is the low sink / source capability of the pins. 8mA per pin IIRC. For all things digital, that's fine but I've used them for other things like the simple LED and using digital pins to power sensors (I can turn them on and off that way).

Can you expand on this a little (bearing in mind I do not have a Netduino - mine is on on it's way - and have never even played with an Arduino).

Is the implication that for "other" boards (Arduino) the current from the pins is often large enough to actually drive sensors and the like but, with Netduino, I'll need an additional power source whenever I have something hooked up to a pin that I'd like to control?

Thanks.

Mark

I turn away for a few hours and when I come back I am a fighter pilot travelling near the speed of sounds :-) Seriously, my needs are very modest (and not defined to any great degree yet). I just potter around in my mickey mouse little 172 at maybe 125 knots maximum and reaching 6,000 feet is a "big day" (for the fellow pilots, even under IFR the MEA's around here - or at least where I fly - are in the 3-5,000 range). So, I don't anticipate any constraints with what the GPS modules seem to be able to offer. Anyway, this is good to know and I appreciate the comments. I'm off to try and come up with some reason to actually build something that will need the GPS now :-) Thanks again. Mark

I'm very much the newbie in town - but this looks promising. http://www.ladyada.n...ensors/fsr.html Mark

You need a GPS receiver to get the GPS data, and some way to store the data. The Adafruit GPS shield has both SD and GPS capabilities--so that might be a good start.

Thanks Chris (for the record, I'm really impressed and appreciative of the prompt and helpful responses since I signed up).

My confusion stems from the fact that if I look at the AdaFruit Shield (http://www.adafruit....&products_id=98), there is a specific message saying "Please note that this shield does not come with a GPS module, they are sold separately". So it looks like I need both, no?

Thanks again.

Mark

A couple of questions about what I'd need if I wanted to get GPS information into a Netduino. It seems I need both a GPS shield AND a GPS module. Is that correct? And, if I want to store data I'd need a GPS data logger. Correct again? A bit confused... Also, does anyone happen to know if the typical GPS support on a device of this nature (using a GPS module) supports altitude? I am a private pilot and - just for the heck of it - interested in building something for my (small) cockpit that uses GPS information. I actually have no idea if all GPS devices that follow standards have the capability to obtain an altitude. I've tried finding this out but can't find any reference to this on any of the devices I found. Thanks. Mark

I do some videos on youtube. Nothing to great since I also started a little while ago, but if you are looking to get started quickly then those should help.

I can always take a request and try my best to make a video tutorial. Also if you stay tunned later today I will have a video tutorial about motors.

My Youtube Channel: VCSandARM
My website, it has all the code from the videos: OZ-Solutions

Hope that helps!

Thank you, both for the response and for taking the time to produce these videos. I will take a look and let you know if anything springs to mind. My most pressing request is probably something that isn't best addressed with a video. I would really like a "Netduino Newbie Guide to Ports" - what I get, which sort of applications they best address, how to use them, etc, etc. I guess that, in a way, this is platform independant - why I'd use a GPIO or a UART and PWM or ADC, etc, etc is something that probably applies just as much to Arduino, I'd guess. But getting these basics under my belt would be very helpful in understanding what I will (soon) have at my fingertips. I haven't found any specific content about this yet - just lots of people talking about them from a position of awareness of what these things are :-)

Thanks again.

Mark

Is there a short/medium term plan for training content for Netduino? Theer are some nice little video's on the site but they are obviously just a start and pretty sparse. As someone who is just getting into this whole thing at a basic level (just ordered my Netduino last night!), I am a sponge for any and all such content. I understand that this is all relatively new but I also know (or at least suspect) that a lack of educational content is a blocker for anyone looking into this. By the way, my interest is beyond basic "light an LED" or getting it to respond to a button (although those video's are still useful, especially the event handler one which sparked my thinking about how this could be used). However, I have a need for "fundamentals" of physical computing with a platform like Netduino. I'd like to read about the various types of ports on the Netduino, when they might be appropriate to use for various scenarios, what sort of interfaces are required/suggested, how I'd program/use these ports and so on. I've decided to take the risk and see where it leads but it would be great to know what the plans are in this area. Thanks. Mark

Waterproof?

Waterproof would be good (persperation) and also I would prefer some other way to securely mount the switch without drilling.

Thanks.

Mark

Sometimes they are referred to as "momentary contact switches".

I think if you contact places like Mouser.com and Jameco.com (and probably Sparkfun.com) you can check out their online/offline catalogs.

Being that flat... you might get stuck with a surface mount... which is harder soldering.

You raise another issue I forgot - the surface on which they are mounted is not flat :-) It's basically a cylinder.

Mark