Testing The GA144 Eval Board
The folks from GreenArrays were kind enough to send me a GA144 evaluation board [pdf]. I have had it for about a month. I have taken my time because I was also rebuilding my shop while evaluating the board. And building a little gadget for testing. So now down to work.
I took a long read of the board manual.
Here is the latest software page (all free).
You will need to learn a few things.
I suggest starting with these documents:
This stuff is all heavy going. Every word has meaning. I suggest reading it over a number of times. But that is not all you need to do. You should be interacting with everything you can once you have a little learning under your belt. So lets do something with the board.
My shop is a hobby shop so I do not spend top dollar on accessories if I can help it. Which brings up the next step.
The first thing you need to get started is an anti-static work area. This does not have to be full up industrial if you will THINK before you act about the anti-static consequences.
You will need to get an appropriate number of black anti-static bags and slit the edges to extend the area. Tape them together with packing tape (I like the clear) with about 1/4" to 1/2" ( 1 to 3cm) overlap so that the bags are making electrical contact. Then flip the contraption over and you have a moderately conductive anti-static surface. Which means - don't lay your operating circuits on the surface.
That is just the first part. You must clip your soldering iron to the bags. Check the connection. Also connect the ground of any circuit you are working on to the bags.
Now here comes the important part. Once you have all the above set up - always touch the anti-static mat before working on anything or testing things. That is where the THINKING comes in.
When working with a new component, lay the component in its protective bag on the anti-static mat for a few minutes to allow any static voltages to equalize. Oh yeah. Keep the humidity up. It tends to leak off static charges.
Of course if your budget is not limited, go the whole professional surface and wrist strap route.
Unpacking and Setup
You now have a suitable work surface with everything grounded at one spot (or as close to that as you can manage).
Put your GreenArrays board (or chip container) on your anti-static surface and let it sit for a while. Drink a cuppa. Fill out your travel expense forms. Five minutes - more or less. Besides the rule is - no matter how excited a new chip makes you. Don't rush. THINK.
Now it is time to pull the board out of the bag. Touch the anti-static surface first. Since the anti-static surface is fairly conductive (it can go as low as 10K ohms between contact points) you will want to mount the board on some kind of standoff. I used 3/4" long 2-56 screws to do the job. Since I'm putting the round heads in contact with the anti-static mat each will require 2 nuts to hold it to the board. In addition on two of the "stand offs" I added a serrated lock washer and a solder lug. I attached these to the grounds on the screw terminal power connector. Thus when ever the board is standing on its standoffs it is connected to the protective mat. Of course it is a good idea to clip a ground lead to the anti-static mat. But in case that clip comes off...
Next step is to remove the indicated jumpers and test the output voltage of the regulator. Once the jumpers are removed plug in the USB cable to your computer and GA144 board and test the voltages. Then remove the USB cable from your board and install the jumpers. Now plug the USB cables back into the board and you are then ready to start in on software.
Talking To The Board
Windows 7 has no terminal. So for testing purposes I suggest putty.exe. The GreenArrays guys are familiar with it and can help you with that section of the initial checkout. They have been most gracious and helpful to me despite the fact that everyone tells me I am not the easiest guy to work with. I make up for it by doing better work. I hope.
You are going to need the GreenArrays software suite to go further so if you haven't loaded it already get it here.
To build you confidence before you start locate the file OkadWork.cf in your working directory. Make a new subfolder called “Restore Point” and save a copy there. Should you mess up totally you can restore that file to the working directory and return to where everything started. There are utilities to do that more or less automatically. But that would just be more stuff to learn that is not necessary for the experiments we will do to start.
Now would be a good time to go to the GreenArrays and Forth blog and read the tutorial on the editor. Now go to section 11.2 of the arrayForth users manual and follow the instructions there. Pay especially close to section 11.2.1 and its subsections 1.e and 3. It is very important to edit page 202 to confrom to the port numbers your computer assigns to the USB ports you are using. And don't forget to do this every time you install a distribution. I forgot that and the GreenArrays guys were kind enough to figure out my error and suggest a correction. (fix the port assignments of course).
All That Hardware To Turn On A Light?
Now comes the final test (for now) I built a simple LED lighter with a bender so I can eventually make light and sound. You can see the schematic below.
Although it is designated for port 715.17 I initially hooked it up to port 600.17 as suggested in section 9 of the arrayForth users manual. Once you are wired up you are read to test per Section 9. Start with the command host load panel which will load the hardware testing panel. Follow it with talk 0 600 hook upd and you are talking to node 600. Now for the final test. Make sure you are in hex mode (F1 key) and type in 30000 io r!. The LED will go on. Type 20000 io r! and it will go off. Type in 01 io r! and you are in the weak pull down state.
So how do I like it so far? Working with the software and hardware will stretch you. It is nothing like anything you have ever done before. In some ways very primitive and yet the setup supports some of the most advanced hardware around. What made it easy for me is how responsive the GreenArrays guys have been to help me start up the learning curve.
I'm working on some simple bit banging experiments in order to learn my way further around the chip and its software. I'll have something to say about the experiments when I have completed them.