02/24/2010 - EDIT: An updated version of the code used to drive 3 Easy Drivers via and Arduino and a classic NES controller. Not a whole lot of changes to the original, just a little bit cleaner, more concise, and thoroughly commented.

As luck would have it, my stash of NES controllers (qty: 2) were in the same location as my stash or N64 controllers! I couldn't resist.

Shapeoko needs a "joystick". All CNC machines have one. They are either software controlled (buttons on screen) or hardware.  They are necessary to move the gantry out of the way and to "home" your machine to the material. I have an old joystick from an arcade I build a few years ago that I have been planning to use.

However, one of the problems using a traditional joystick is that it takes up one port for each direction you are trying to capture. So in our case we would want: Forward, Back (Xaxis), Left, Right (Yaxis), Up, Down (Zaxis). That's 6 inputs we would need!

The NES controller doesn't need one output for each button because it's digital. What's that mean? Good question. Here is how I understand the NES controller to work: The chip inside the controller is polling the status of the buttons at a rapid rate. When the buttons are not being pressed, the result of the poll looks like "11111111" (one bit for each button). After the controller is done polling, it sends that string to the console (in our case the Arduino) which is then interpretted by the program into whatever the button are mapped for.

If you press a button then the string changes to reflect it. For instance if you press the select button the string changes to 11011111. The cool part about this is the arduino need only use 3 ports to interface with all 8 buttons! The three ports are for "Clock", "Latch", and of course data. The data wire is where all the action is! Clock and latch are there to keep the timing correct.

To be honest I don't completely understand how it works, but I figured it out enough to capture the inputs with the Arduino and light up the corresponding LEDs! I would like to say, as a side note, working with a "digital" also prevents you from having to debounce the button pushes. Because that debounce logic is already in the chip that's doing a2d inside the controller! we're just taking the "clean" data :)

Here's a quick video of the setup in action. The code is below if you want it.

Now that the buttons are mapped and I feel pretty confident about capturing button presses, I am going to get to work on writing the code to control the step/dir functions of the easy drivers.

After frying my old Arduino Duemilanove I knew that I'd need to get a new one, and fast. Sparkfun to the rescue. I sat down, ordered a new one (the standard chip is now an atmega328!), ordered some jumper wires and a new breadboard while I was at it. The three tiny breadboards were ordered before I fried my easyDrivers. FYI: they are the perfect size to hold and tie in to a single EasyDriver (v4.2) with headers soldered on!

I also took the liberty of ordering an atmega328 chip with Arduino bootloader. Because of the semi low cost (~$5), i figured it was worth trying to revive my old arduino. First thing I did when the new gear came was pop the old chip out of the fried arduino and popped in the chip in. Yahtzee! My old Arduino is not only alive, it's also upgraded to a better chip. Needless to say, that was good news.

While I decide what path to take for the rest of this project I also ordered more easy drivers. Although there's a good chance I will be using a different solution by the time I complete this project, but I feel comfortable with the easy drivers and know they will work for the time being.

Also, I have been thinking very much about cutting the PC out of the loop entirely. As is, the PC (currently my Dell Mini 9) is simply streaming a gcode file to the arduino. From there, grbl does the rest. Seems like overkill to use a PC for such a simple task.....Enter a second arduino.

The second Arduino will have some FAT library loaded as firmware (have yet to decide which one) and be connected to an SD card shield! The arduino will then read one line of gcode at a time, send it to the primary arduino and wait for the "OK" before sending the next line.

Also, I ran across this instructable, which gave me a pretty rad idea: Why not use one of my old N64 controllers to control the mill? I'm thinking about going to a two Arduino setup as is, with one Arduino not doing much work there should be plenty of ports and programming space available to implement a program which will allow me to jog the machine around, along with possibly homing the Z axis.

In fact, although the feature has a certain amount of "coolness", its quite practical. After all, one does need a way to gracefully move the machine to a "home" position. Right?

To make matters worse: I fried my Arduino too! It seems that when I tried to demo my machine at the hackerspace meeting I crossed the +24v from my Power Supply and the GND, which essentially meant that I sent 24V into the arduino and then into the Easy Drivers. Both of which were only expecting 5V....

Right now I have a new Arduino on its way from Sparkfun. I will order the easy drivers tonight. In the meantime I'm hoping to learn how one may protect against accidents like this....

But I'll stay positive because, to steal a quote from Dostoyevsky, "A just cause is not ruined by a few mistakes" :)

In retrospect I should have done some color coding for step/dir and especially for the motor harnesses. Chalk that one up under being a rookie I suppose...

OK, so now that everything was setup, I was ready to manually send gcode to the arduino via the serial monitor in the arduino IDE. Laptop is powered up, arduino is connected via USB, XYZ axis' are connected to the arduino. All Set:

I power up the 24v Power supply and everything goes crazy. The X axis is wobbling back and forth, the Y axis is stalling itself out, and the Z axis was making a really creapy humming noise. Power off. Quick.

After trying a few more times, and double checking the pinouts in Simen's config.h file. I couldn't locate the problem. All I know is that if I don't hook up the arduino then everything is fine. The motors will sit there quietly, and everything looks like it's in order. But, the moment I hook up the arduino... bad stuff happens. Here's a video demonstration.

 

So, like I said: That's it for tonight. I'm going to enjoy this delicious Pale Ale from Bell's Brewery and go to bed. Maybe tomorrow will be the day?