Hi Coyttl, What voltage are you looking to measure? The Analog Digital Converter in the Netduino Plus is a 10 bit ADC. The internal reference is 3.3vdc and the design input to the analog pins is 3.3 vdc also (I don't recommend a applying more than 3.3 vdc). With 10 bit resolution you will get a reading from 0 to 1023 (3.3/1024= 0.0032 per unit). Most like to take say 20 readings about 20 to 50 milliseconds apart them average then. Repeat this at what ever interval that you want. This reduces errors due to electrical noise etc. If you want some code that may help you get started there are several examples for TMP36 temperature sensors written in C# and Visual Basic (just replace the TMP36 input with your voltage input. If you need more help feel free to ask additional questions, the more information you can provide on what you want to do the easier it is for someone to provide the answers that you are looking for. Hope this helps. Chuck

We are sending your update via USPS, should be there by the end of the year (2013)


Sometimes called snail mail for a good reason.
Chuck

This is a little hard to explain so here go's
I have light on for 16 hours off for 8 forever loop
simple
I have another loop that kills the 1st one in 14 days
Is there a way to track the 1st loop
My problem is that when the main loop happens the light may have already been on 0-16 hours no way of knowing.
Would like to start it at the same time it left off.
My thinking is, I probably need an external clock.

Perkunas,

I may have miss understood your question, but if I didn't I would would pick a loop with a time of say 1 minute. Then on each loop I would increment a counter.

In visual Basic something like this (most likely not correct, meant only to get you started)
dim OnCounter as integer = 0
dim LightOn as boolean = false

OnCounter = OnCounter + 1
LightOn = (OnCounter > 0) and (OnCounter < 961)
if OnCounter > 1440 then
OnCounter = 0
end if

Then use the OnCounter to control a relay for the light.

Also easy to do in C#

Hope this helps.
Chuck

Thanks for the info, I am ordering the 498. Yes, the class would be helpful, I apreciate that.

Giuliano,

You adding a display to the sprinkler system?

I have the 498 and it works very well with Stefan's NetMF Toolbox, it took about 30 minutes to solder all of the pins and headers but you should not have any problems (.1" between connections). Plus you only use a few IOs.

Chuck

Perkunas, There are several current limits that you need to watch. The most limiting is the per pin current rating. From the Netduino Hardware Specs on Netduino Hardware Page of Netduino.com: max current: 8 mA per pin digital pins 2, 3, 7: 16 mA per pin analog pins 0-3: 2 mA per pin microcontroller max current: 200 mA total The current draw for the optical isolators will exceed the pin limits unless you use a transistor between the optical isolator and the IO pin. The limit for the onboard regulators is 800 milli-amps, but I personnaly don't like to exceed about 50% of that unless I have good heat sinks or fan to help maintain the temperature of the regulators. Also picking a power source that has a voltage that is close to the 5 vdc output helps (7.5 to 9 vdc) the heat produced by dropping the extra voltage is less the closer you are between the input and outputs (heat or power loss = current x voltage drop regulator for Liner Voltage Regulators). If you want more information on the onboard voltage regulators, go to the hardware page for the Netduino, open the schematic drawing, lookup the part number for the 5 vdc regulator (or 3.3) and google it (MC33269DT-5.0G or MC33269DT-3.3G), you should be able to find a data sheet. I agree with Dave and reccommend a separate power supply to drive the relays, either mechanical or solid state. Hope this helps, Chuck

Adam, Not trying to down play the many capabilities of the Netduino line, but you would be hard pressed to match the capabilities of a commercial Pan, tilt, zoom (PTZ) camera. They start at around $75.00. I have an Edimax with 2 megapixil camera, IR for zero ambient light. It can send email, record to SD card, be operated from iPhone or android phone. I of the better features that would be difficult with memory capacity of a Netdunio is security login and Https: protocols. Now if you want to be a robot or one of many other projects then Netduino's are great. Chuck

Arbiter, One possible source that you may have over looked is old cell phones. I was looking for a 2gb micro when I realized a had a couple of old cell phones that had SD cards still in them (AT&T Samsung dumb phone). If you don't have any old phone some phone stores recycle the old phones and may give you a SD card. Chuck

Galibore,

I have not tried that multilexor, but I did buy and put together one that was made by a forum member to work with the Netduino and he has code also. 32 IO multiplexor

I think that I paid $20 for it and it came with the chips and hardware. It works with Stefan's NetMFToolbox which is another plus.

I checked that it worked but haven't got around to playing with it futher.

Chuck

That's what I did. I unplugged the sensor and I read no power at all, well .0L which I think means open or infinite.

Giuliano,

Most multi meters that I have use 0L would mean overload or over ranged, does your meter have auto scaling? If not check that the meter is not in a milli volt range.

Most meters would indicate a voltage (in milli volt range) when not connected just from RF radiation.

Check your meter against a none source such as a AA battery, make sure you use a DC scale not AC. It should read about 1.5 vdc.

As far as the netduino you can hook a wire from the 3.3 volt header to the input pin that would be connected to the alarm. Then move the wire from the 3.3 volt header to ground. If program senses the change the netduino should be good.

Good luck,
Chuck

Daniel, The answer lies with your girlfriends interests, if she enjoys puzzles, building thing and being creative then she most likely will enjoy using a Netduino. If she get discouraged easy when it doesn't work on the first try maybe not. I don't know of anyone that has ever tried to build something and had it work exactly the way they wanted it too or after finishing didn't come up with something else to improve on their first effort. But for most that is the challenge. Best bet is to get her one to try, she she doesn't like it, then you have one for yourself (you have to look for the silver linings sometimes).