Hi,

I am working with the rf modules. I have two netduino boards to whome i want to connect the receiver and a tramsmitter. Now i need the possible circuit design and the code for sending the numbers from 1 to 100 using the c#

Can any one help me out with this ??

If you want one Netduino/Arduino/PC to just be a receiver, and one Netduino/Arduino/PC to just be a transmitter, then WRL-10535 RF Link Transmitter - 315MHz and WRL-10533 RF Link Receiver - 4800bps (315MHz) would do the trick. They are US $3.95 and US $4.95 respectively.

Keep in mind that each module *only* does one direction. If you need bi-directional, you would need to either go XBee, or equip each unit with a 315MHz and 434MHz unit (one in send, one in receive).

-dan

Is there a way to determine the max data rate of the serial port? Can I even achieve that rate in managed code? Does blinking the onboard LED have any impact of performance?

Thanks!
-Arian

Depending on what you need to do, search the forums for "SimpleNGen" Corey Kosak has done some work to convert C# into native code which gives a pretty substantial performance improvement.

-dan

I am working on a circuit that will be able to drive a 115VAC half wave vibratory feeder using the Netduino. I attached the circuit diagram to the post.

As I am not realy experienced in this I was wonding if someone would be able to have a look at the circuit I designed and provide feedback to ensure that the circuit is sound. I really do not feel like killing my Netduino (or myself) by connecting to mains... I know that I lack fuses in the design as well as values for components, I will calculate those later.

Any help with this is much appreciated.

Regards

From your schematic it looks like you are using an optoisolator to then switch some stuff to then turn on the mains. Is that correct? If thats the case, you should look at the Arduino relay circuit.

-dan

With a netduino classic or plus you need a TTL to RS232 converter. I used two successfully:
http://wiki.netduino...hifter-SMD.ashx
http://wiki.netduino...-to-Serial.ashx

perhaps this thread could help you with code:
http://forums.netdui...rt-code-review/

You can also wire up a USB->Serial adapter directly to the serial pins on the Netduino. But be very careful. Some USB->Serial adapters output 12v and that will cook your Netduino (unless you use a level shifter). The USB->Serial adapter I have happens to put out TTL levels.

-dan

AC MAINS- it's about 30 years, here in Italy, that in any house/office it must be installed a safety switch. In US that's not mandatory? Basically it is a switch (normally closed), that opens as soon the difference of current between the hot and the neutral are above 30mA. This would be the typical situation when you touch accidentally the hot wire, but all the current flowing through your body is going toward ground. That makes the switch opens.
It works very well, and you almost don't feel anything: too fast to feel the shock.

Cheers

Mario,
We have much the same regulation here, except it doesn't apply to all outlets. Outlets in a wet location (WC/bathroom, kitchen) and exterior are required to be GFCI (the technical name for the "safety switch" you mentioned), or protected by an upstream GFCI or GFCI breaker.

On the one hand they are nice to keep you from frying yourself, on the other hand they can be a complete pain in the butt. I have to replace the exterior outlet I plug my car into in the winter once every year or so because it goes "soft" due to the draw of the block heater on my car.

-dan

Dan, I feel your pain! I had to chuckle about the engine block heater! Your bio doesn't say where you are at but I remember well the "dipstick heater" from my youth in Rhode Island! What are they? 100W? Not much good when the temp is at -20 degrees...

Good points about the safety switch, aka GFI (or Ground Fault Interruptor). But it only works when the wiring is correct: in the U.S., the AC Neutral to the large, wider slot, the AC Line to the shorter slot, and a GROUND to the half-moon slot. Get the line & neutral reversed and your at risk - even with a GFI. When I lived in Germany, the locations were determined by relative location to the ground lug. It is easy either way to mis-wire by a "do-it-yourselfer".

Bill,
I live in Anchorage, Alaska, USA (Yes, some people forget we are part of the US :{). Normally temps get down to about 20F, but at times to -20F.

The way I remember how to wire up an outlet is "B2B - Black to Brass." All the outlets I've dealt with all have a brass and an aluminum side corresponding to hot (or black) and neutral (or white).

-dan

Dan,
I am humbled.
Anchorage, eh? Makes my winters in R.I. seem like the Bahamas.

On my bucket list I have "trip to Alaska". I hear many good things about your beautiful state. I will get there someday.

You are spot-on on the colors. "Black-on-Brass" "White-on_silver". When wired corerctly WHITE & GREEN cannot kill you. But, Never trust the colors.

Am I being a PITA about this subject?

Regards,
Bill

We aren't that much different than the lower 48. We just have longer winters and shorter summers. Winter typically starts mid September and runs till mid April Oh, and its dark here, at the winter solstice the sun comes up around 10:30 and sets around 3:30 .

When you come, come in the summer time. June is a good month, not to hot, its usually pretty sunny. August is the worst time, it rains almost every day. In fact, last year it rained every day for 36 days in a row

As to being a PITA on the mains issue, I don't think you are. People need reminders sometimes that the mains can hurt you :-)

-dan

Thanks for the reply. This sounds promising. What is the largest SD card the netduino plus can support? I can see myself having the main application on the main memory and loading and unloading dll's from the SD as needed.

Chris, Stefan, Mario, etc, correct me if I'm wrong.

You can't unload an assembly after it has been loaded. In the regular framework world, the way you handle that is creating a separate AppDomain and unload the entire AppDomain. I don't know if something like that is possible with NETMF though.

-dan

nobody? It's impossible to work on them now as it takes too long to deploy stuff.
I have 3 netduinos, happens on all of them. To build and start the MS emulator is instant.

any ideas welcome

I've had this issue happen to me from time to time. It is why I built a box with a switch on the USB power lines to power-cycle the Netduino. I found this cleared up 99% of the deployment issues I had.

-dan

so i would like to take and store (possibly display at a later stage) temp readings from upto 4 sensors, these would first be read over usb I suppose if easier, or stored somewhere for retrieval via usb or on SD card for reading in via the pc. SD would probably be perfect as its safe if power is lost and I assume i will want this to run on batteries eventually. I can then take the values and plot vs time to see the temp curve of the oven. Not mission critical but I think fairly interesting to know if you plan to bake bread in the oven also (I do).

If you have any plans to display the temp in real time, you have a couple of easy options. You can get a serial LCD "backpack" from SparkFun for around $25. Another much cheaper option (while more complicated) is to use 74HC595 shift registers and 7 segment LEDs. Each '595 will do 8 bit serial-in, parallel-out and they can be chained together. You could also use a STP16C596 which does 16 bits. This will allow you to display the temp using only 3 lines on the Netduino.

-dan

@Dan: aren't you scared about the quake? I guess the your's in one of the most dangerous areas for the quakes!
I have seen some of medium/high intensity here in Italy, and I must confess that's horrible!
Anyway, despite this dark page, my wife loves to visit those places!
Cheers

Mario, I missed your reply until today :/

The quakes don't bother me one bit. You get used to them after 26 years :-) Only one had me concerned, and that was a magnitude 7.9 quake. Usually, the ones we feel are in the magnitude 4 to 5 range.

-dan

Rexz, welcome to our place.
Your idea is theoretically realizable, but you need a powerful platform for both the recording and the playing side.
The Netduino hardware itself is very powerful, but you should wipe out the .Net Micro Framework, and use pure native code.
This consideration worth also for the Arduino side: I'm not sure an AVR would be able to manage a real-time stream.
However, it depends on the sound fidelity, though.
Cheers

Mario, the new Arduinos are moving to an ARM chip (Atmel SAM3U at 96 MHz) and should be able to handle this task with ease. Arduino launches new product at maker faire

-dan

Hi Chris,

I did know that screen! Thank you!

However, I really want to deploy a single project, the one I marked as startup project! But this is not what is happening (see my reply to Stefen).

What do you suggest?

Igor.

Igor, an easier method than fighting with the config screen is to unload the projects you don't want deployed to the Netduino. That is the method I use.

-dan

I don't have much experience about LiPo-charging, but to be honest, I don't like the charging/detecting circuit above.
I am not sure, but it seems that you have to balance the charge when two or more LiPO batteries are connected together. Another clue is that there's no LiPo batteries chargers for series pattern. You find balanced chargers, single-cell chargers, but no double-cell chargers...at least I wasn't able to find them.

Mario, you are very much correct. LiPo batteries *must* be balance charged.

The other thing I would say is if you are charging LiPo batteries, you really should get a "LIPOSACK." Should something go wrong with the batteries, it can mean the difference between some smoke damage in your house and a full on fire.

-dan

Hello Dan,


This is exactly what I am doing today. However, I would like to see if I am getting out of my mind or if there is someone else who is experiencing the same problem... do you have this problem?


Thank you,


Igor.

I do indeed. I wouldn't say so much that is is a defect as it is the way that netmf and VS work together. When VS is uploading the projects to the board, it expects that every project is needed. And its kind of a crap shoot as to which assembly gets picked as main.

Most of the time you won't have multiple non-related assemblies in a solution, so for most people its a non-issue.

-dan

Please advise best way to see if some on is available to discuss further and
agree on price and time frame.

Sorry, we aren't going to do your homework :-)

-dan

So I thought that I would share my progress as I round onto the home stretch of having a fully functional CNC machine that can create parts and PCB's from CAD drawings.

Its funny you bring this up right now, I just did a test cut of a PCB with my CNC machine (Fireball V90) last night. I've been in the process for over 6 months to get it setup and dialed in.

I can't quite tell from the picture you posted, but that looks like acetal (trade name Delrin). What feed speed and mill bit did you use to cut that?

If your looking for a very precise spindle for cutting PCB's, the TB-650 package by Richard Stethem is an excellent (albeit expensive) spindle. The run-out on a Dremel is way to bad to etch a PCB with anything less than .012 to .015 traces. With a dialed in CNC, a low run-out spindle, and the proper bits guys have etched traces for QFP chips.

IIRC, the run out on the TB-650 is a thousandth of an inch. He doesn't have any TB-650's listed on his store right now, but if you email him he can get you one in about a week as they are all custom made. One of the super nice things about the spindle is its entirely tool-less, and the design of collet mechanism means everything is perfectly balanced. Which is pretty important when your spinning at 25,000 RPM :-)

One thing to keep in mind with this setup is the motor draws about 10 amp continuous. To power my spindle, I used a HP DPS-600PB power supply that had some conversion work done to make the 12v and gnd leads easy to access.

Where have you been getting your bits from? I've been buying the resharpened bits from Drill City.

Have you thought about limit switches? I'm using Opto-Interrupter Electronic Limit/Home Switch for my limit switches. I was originally going to go with simple mechanical switches, but it is really hard to get 100% repeatable precision with mechanical switches actuated by a push rod of some sort.

One thing you may think about adding to your setup is a relay to automatically turn on/off the mains for your cutting head. Not only will this reduce the run time on the cutter, but it will also ensure you don't snap a bit by forgetting to turn on the spindle. This is how I have things setup on my CNC, its really nice to have everything startup/shutdown automatically for noise reduction.

A mod I'm going to do to my CNC is build a plastic skirt with slits cut in it (think the heavy plastic "doors" you walk through at the warehouse clubs which separates the big walk-in coolers from the rest of the store) and hook up a vacuum to that to hopefully automatically suck up the dust. If you use a vac for sucking up the dust from cutting a PCB, you will want to use a HEPA filter. The material PCB's are made from is nasty when ground up.

Anyways, its *way* past bedtime.

-dan

What my project intails so far is I will need to controll about 8 air actuated valves. These will have the DIN connecter plugs. I would like to set this up with an 8 channel or better relay board to switch the valves. So what would be the most cost effective and simplest way of doing so?

I will need to input to the Netduino as well with a few different devices. Prox switches, a thermo couple, some manual buttons. E stop for instance. Id like things to be expandable incase I might need to add some stuff later on. Im in the very beginning of the design faze and this is one of the most important parts. So here I am

I would design my own shield (daughter board). Its not terribly complicated, if your interested I can share mine with you. The one I've built has two relays, and 1 or 2 inputs, and a couple of transistor driven output. You could easily take what I have and scale it to your needs.

The one caveat with my design though is its one pin per output/input. You can easily change that though if you need my by using some '595 chips for output. A '595, and its equiv on the input side allow you to control a virtually unlimited number of inputs/outputs from just three pins by using SPI. Or, you can wait until Secret Labs produces a "Mega" version of the Netduino (hint, hint) which has many more digital I/O's

-dan

Right now I can run about 60 IPM without stalling the steppers and I'm pretty happy with that, but I expect I'll want faster in the future. I'm running 12V and anticipate cranking that up to 30-40v once I know how to do that without toasting my motors.

If your not afraid to spend a bit of money, Probotix has a 40v, 10 amp DC linear power supply for $86.

What are you using for your hold down? I'm currently using MDF, but I have delusions of one day building an 80/20 T-slot spoil board. I could make one for about $40, however they want $39 per stick to ship to Alaska, and I would need two 3"x36 sticks. You can get shipping on that down a lot if you live in the states.

-dan

This information would do well on the wiki!

Hi All,

This is my first post so I hope I have put it into the correct section. I am also very new to electronics.

I seem to be having a little trouble with this Reflective Object Sensor. I am building a CNC pipe cutter and I am using this to measure the degrees on the chuck side. There doesn't seem to be enough current through them to even switch a opt-copouler on.

Second Question:

Is it possible to use this on the Netduino or will it lose count.

Thanks alot for a wonderful product. It is amazing what it is possible.

I will be posting my project up when it is complete... and all the software.

Thanks for the help in advance.

Wes,
Welcome to the community! Can you please post a schematic for how you are driving the sensor? This will help us figure out where the issue is.

-dan

Yes, it is ohms. You can simply use one 165Ω resistor, if you can get it - Mario has suggested two 330Ω resistors (in parallel), because 330 is much common value than 165 (330 is in the E6 standard EIA decade values, while 165 is in E96 - but these should be rather easy to source nowadays).

CW2,
I think reactive wants to know how two 330 ohm resistors in parallel would magically get him to the value of 165 ohms.

To answer that questions you have to understand the difference between resistors in series and parallel. In series, resistors are additive - that is the total resistance is equal to the sum of all the resistors in the chain. So for resistor values of 10, 47, and 100 the total resistance would be 157 ohms (10 + 47 + 100).

In parallel, it divides. with the formula being R = 1 / ((1/R1) + (1/R2) + (1/R3)...). So for values of 3, 9 and 18 the resistance would be 2 ohms -
1 / (1/3 + 1/9 + 1/18) = 1 / (6/18 + 2/18 + 1/18) = 1 / (9/18) = 1 / (1/2) = 2 ohms

In the case of two 330 ohm resistors the calculations would be:
1 / (1/330 + 1/330) = 1 / (2/330) = 1 / (1/165) = 165 ohms

-dan

Darrin, anytime you can post the code is appreciated.
I'd like to start learning G code better so I can make a simulator in autocad.
If anyone ever needs help with Autocad, its what I do for a living, so happy to help (for free...).
I'd like to further Darrin's work though, not make my own parser.

Where were you on Sunday night when I was battling AutoCAD :-) I actually ended up writing a craplet to spit out some g code to do what I needed (drill a hole every .5 inches along the x and y axis in a 12"x12" board. 3-4 hours with AutoCAD, and nothing (I'm an AutoCAD newbie), and 5 mins with some code and done :-)

The whole point of my exercise was to build the top piece of the vacuum hold-down table for my CNC machine :-)

-dan

Lol, I just finish building a CNC machine in my living room and I live in a one bedroom flat (with a very understanding wife).

Just want to say a BIG THANK YOU to everyone who is working on the awesome code, I am currently using an Arduino, and it is really limited I can't wait to rebuild the machine with my beloved Netduino.

PS. Before anyone asks, Yes my CNC is made from bits of IKEA furniture "bargain corner". It turned out surprisingly accurate, especially since I have only spent £90 and that includes the cheap Dremel clone.

Keep up the good work!!!

Where did you pickup your linear guides at? Are you using acme screws or all thread? Do you use anti-backlash nuts, or program out the backlash?

-dan

I'm working on a project where we are going to be having a large number of Netduino devices talking to our SaaS Platform. When we ship the units, they are going to talk to our platform using some simple web services, but we have to uniquely identify each unit.

Is there *any* way to programatically obtain a unique ID for a Netduino to use as an ID in the web services?

If not, we are thinking of a few other ways to do this ... but I was hoping there could be something?

Scott

I'm sure Chris has better/different ways, but what but about using the MAC address? If your using the Netduino plus you can write a unique ID to an SD card and store it on there. Depending on your timeline, I believe the ability to read/write a small amount of data to the on-board EEPROM is coming in NETMF 4.2.

-dan