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

Yes I'm using a computer power supply and it works great. If you need more power you may want to consider something bigger.

You can buy an HP DPS-600PB server power supply off ebay for around $15 which will supply almost 50 amps. It will require some modding to add the terminal posts though. I use it to drive the spindle for my CNC.

If your looking for a fully assembled solution that will provide just shy of a 100 amps, a very good friend of mine sells a fully converted HP DPS-600PB (x2) for $47. His target market is R/C where they use them to drive their battery chargers. I've seen the kits in person, and he uses really high quality components, no 16 AWG wire :-)

If your not interested in buy his kit, get some *good* 30 amp binding posts. You can use the kit details for a parts list if need be.

BTW, I don't get a cut of the proceeds, just recommending them because they are HQ!

-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

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

Thanks for the offer of a free dinner and well done on the research!

Threads will always have people that disagree. There are some basic recommendations in the thread you found:

• use a slow clock speed, the SPI interface becomes more reliable when you slow down the clock,
• use filters to try and remove high frequency noise,
• use logic chips to clean up the signals before they go to the next device,
• use cables that have shielding (a metal screen around the outside of the cable).

I think all of these things will help, but the railway may still have too much electrical noise for the system to work reliably.
If you have the time and some parts you might try it out with one or two shift registers to see if it can work on your railway. I'm sure there would be lots of interest in your results on the forum.

The Texas Instruments note goes into detail on what the problems are.
They end up suggesting using some transceiver chips (SN65C1167) that are used for RS422/RS485 interfaces. This will cost more to implement, but it will be more reliable and may make the system work.

Regards - Paul

What about breaking the problem down into discreet components, all orchestrated by a master controller? This will require a little bit more on the cost side, but should allow for better expand-ability.

So the issue as I understand it is how to reliabely get a single over a longish distance? The a complete RF transceiver module with the NRF24L01+ chip can be had for $2.32 on eBay. Use that as the communication link between modules. And use a Netduino Mini at each point to do the comm and handle turning on the LEDs, etc.

Just a thought.

-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

I discovered the Netduino a couple of days ago!
I have recently started development of internet-connected devices using the Arduino Uno and an Internet shield.
I am intriguded by the power of C#, multithreading, debug and the many other features of Netduino that make it easy and fast to develop internet-connected devices.
There are, however some drawbacks: limited product range, limited supported devices and related code, limited competition (price), limited support (just this forum?), fewer sample code available, ...

You have the experience, so help me make an informed decision:
1) Based on your experience, what are the 5 key reasons why Netduino is a better development tool for developping custom internet devices that Arduino

2) How do you deal with the restrictions/drawbacks compared to Arduino to reduce their importance

One of the big reasons for me why I use the NetMF platform using Netduino over Arduino is debugging. With Arduino, without going through a lot of gyrations, you have two basic ways of debugging. Serial.println, and flashing an LED. Serial.println works fine if you don't need to use the serial port(s) for other purposes.

With NetMF, you can do Debug.Print (or is it Console.WriteLine - don't my code in front of me), write out to a serial device, twiddle an LED, and most importantly, single step through the code to inspect what is actually going on. Another big thing is the code that you write, is the code that gets uploaded to the board.

With Arduino, if you use the Processing language and Arduino IDE, what you write is not what gets compiled and uploaded. A good example of this is some code I wrote last week, one of my preprocessor directives was wrong. The output from GCC which the Arduino IDE spit out said there was an error on line 133. My code didn't have a line 133. So I had to turn on verbose compiler output, so I could see where the actual file that the Arduino IDE was feeding to GCC was. Then open that file up and see what the actual error was.

That said, both platforms have their strengths and weaknesses.

Another big one is interrupts. Only pins D2 & D3 (IIRC) can be used to trigger interrupts. On the Netduino, any pin can trigger an interrupt. Interrupts are useful to have the microprocessor tell you when something has happened, instead of having to constantly monitor the state of a pin, and do your own checking on if the state of the pin has changed, and if that state is one you care about. For example, you can trigger when a pin goes high, goes low, or both.

-dan

Just as an update, while looking for a recommendation on which Ocilloscope to buy I came across this thread, the RIGOL DS1052E was mentioned as a good scope (I am sure that it still is).

While this model can still be found for sale I found that it has been replaced by the RIGOL DS1102E for the same price range as the older model (was $795.00 now $399.00) and has a 100mhz bandwidth. RIGOL DS1102E

The DS1102E doesn't replace the DS1052E. The DS1102E is a same board, chips, components, etc as the DS1052E, except it has a different label on it, and bit has been twiddled in the firmware to allow capture at 100 MHz. As @nakchak mentioned, with putty (or any other serial terminal program) and some very easy instructions on the net you can turn your DS1052E into a DS1102E.

-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

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

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: 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

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

Have you stumbled upon any scripts to import eagle schematics? I searched Google a bit and didn't find anything.

I don't know how KiCAD does it, but other programs I've experimented with require you to open your schematic and board in EagleCAD, then run a ulp (user language program) they have written to export the data into their pre-defined interchange format.

-dan

Since I took a break from Electrical Engineering in 1997 to pursue other career aspirations, I am sure Electronic CAD and Board Manufacturers have changed a lot.

As I begin the next phase of my project, building a Bill of Material, then laying out the board (shield) and sensor boards... I figured it was time to get some recommendations from the members as far as which CAD software to go with. Not looking to spend an arm and a leg on it. Also, are there an board manufacturers that people have used that are particularly good and maybe support small quantity runs?

NOTE: I have both a MAC and a PC so the CAD's OS is not a deal breaker. I also like the look of the black masked Netduino boards. This would be a preference when it comes to the board maker.

Thanks in advance for any advice.

Depending on how big your board is, if you need cheap proto boards, itead studios can do 10 5cm*5cm two layer board for $9.90.

-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

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

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

I'll try that when I get back home, what I did already try was a full erase, reload tinybootloader, RC4 and I got the same issue. If VS states "Assemblies successfully deployed to device." does it really mean it?

You don't by chance have multiple projects loaded in your solution do you? If you have multiple projects in a solution, everyone of them gets deployed to your board, and then its luck of the draw as to which one actually gets executed.

-dan

Hard to tell how much people are color blind. Only males are affected.

Not 100% true, females can be affected by color blindness as well, but the rates are much lower. 8% for men, and 0.5% for women - Color blindness

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

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

Hi everyone,

I did a bit of rewiring, replacing alot of 12" jumper wires with shorter length breadboard jumper wires. This seems to have gotten things working well enough. Magpie I didn't end up trying different frequencies for the pwm or I2C but I'll keep that in mind if it comes up again. Thanks for the advice Dan, I hope I won't have to resort to a Faraday cage for this project but who knows. It would be nice if you could buy some shielded cable sheaths though, has anyone seen anything like that?

thanks

Buying shielded cable will probably run you a pretty penny. A much cheaper option is get some RG-6 (coax), and carefully strip off the outer plastic shield, then pull out the inner solid-core wire and plastic tube. So what your left with is a braided tube of copper wire. I have used that in the past to make cheap DIY shielded cables.

-dan

Hi Magpie,

Following up on your advice, I read a bit about voltage changes induced by high current wires that aren't even part of the same circuit and one of the things they suggested was to coil/twist the high current wires around each other. I tried this (and also moved them marginally further away from the rest of the circuit) and immediately there was a difference. The gyro didn't lock up the first time but ended up reading wacky values progressively. The 2nd time it locked up still but it got alot further than usual. So it would seem to be almost definitely induced interference. I didn't have any 0.1uF capacitors to run across the motor terminals which they suggested as well. The combination of twisting the wires and keeping them further away and the caps hopefully will be enough to allow me to get this working. If not maybe I'll have to get some low current motors instead.

thanks

Is there anyway you can shield things? Either by putting a shield around your control boards, or around your motors. A cheap and easy way is a Faraday cage. You can build one pretty easily with some aluminum mesh from the hardware store. Look in the window screen section. Be warned, its a real pain to work with, and you will need to have something like tin snips to cut it.

If you fully enclose either your motors or driver boards, you should see your interference go away.

-dan