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Development Log - March, April, May


What follows is the development log (diary or blog) for the game. Whenever I've done big projects in the past I've always found it useful to maintain a log. Lots of blah blah here, mostly unedited. It's been split up by months so that the pages are not too long.

Logging was started on May 11, 2004, about two months after project start. This page contains entries for March, April and May.

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Fixed up the Solar Ride p/f, acquired System 1 doc and wired the p/f such that the flippers, pop bumpers and slingshots work.

Also acquired Basic Stamp 2 kit along with PICAXE processors.

Acquired numerous electronic parts and a laptop. Set up the laptop and got it going as the primary development machine. Wasted many hours with a different laptop prior to that. It didnít work very well.

I ended up with a Compaq Armada M700, which is a P3-650 machine with 128mb of RAM and a 6GB hard drive.

Began writing the Java controller code classes and did testing. Built a crude GUI screen.

lamp testing with BS2

Initial tests to strobe lamps with the BS2. Rigged up eight #44 bulbs and connected them to a ULN2803 Darlington chip. Was able to verify that strobing would work without visible flicker.

May 2004

Began serial port comm testing. Encountered serious problem with Java Comm API. Asked several questions in the Stamp forum and got by the Comm API bug.

Communicating reliably on the laptop at 2400 baud with 8N2 parameters. Or 1200 baud with a tiny bit of error checking added.

May 11

Have been investigating the BS2sx recently. Also of great interest is the HVW Tech Stamp Stack sx, which is cheaper than the BS2sx module itself.

Soldered a regulated voltage supply kit last night. Will test tonite. Can use this for other proto boards.

Not sure whether to get the BS2sx next or to play with the PICAXE.

May 12

Tested the power supply. Works great although LED is flaky. Probably a crappy solder joint. Measured voltage was 4.2 to 16.8 unloaded. Installed PICAXE IDE on the laptop.

Bought some stuff from Active, including 74F138 chips (3-to-8 decoder multiplexor). Plan is to use that chip with the Picaxe and hook it up to a 2803 chip. That gives the 8 strobe lines for the lamp matrix.

May 15

Re-soldered the power supply lead on the LED. Installed the new tip in the Tenma soldering station. The old tip, which didnít work very well, was a Weller part.

Power supply seems ok and the LED is good now. Bought some spacers and attached the power supply to a block of wood. Also attached the Radio Shack 12/24V transformer to a piece of wood with the power supply.

Hacked a 3-position KK100 connector in half, to get two single connectors. I used the single connectors to attach to single header pins on the power supply for both the AC in and DC out. So the power supply hookup is modular.

I can just plug into a 2-position header on the breadboard also.

Cleaned up my work area and organized my electronics files. Also affixed a power bar to the edge of my bench. No more tripping over wires or the power bar on the floor!

On my new breadboard I installed the Picaxe 18A processor and serial port header. Connected it up as per specs with resistors, etc.

Hooked this up to my desktop PC, installed Picaxe IDE there and wrote a simple LED flashing program. Worked great first time. No serial problems downloading code.

So we are ready for Picaxe programming. The plan is to try the lamp matrix stuff. When that works try serial i/f from BS2 to Picaxe. When that works do an end-to-end test from the Java controller code to turn lamps on and off.

After that I could try an actual hook up to Solar Ride. I will need access to 18-20V to power the lamps. I can probably use the small transformer there. If not, I can use the Radio Shack transformer and get from 24V down a bit.

May 19

Wired up the 74F138 chip to the Picaxe last night. But I messed up and didnít realize that the 74138 outputs were inverted, meaning at any one time 7 would be high and one low. I had 6 LEDs hooked up which immediately all turned on.

The Picaxe was dead in short order. Iím presuming there was too much current draw through it. I swapped my other Picaxe chip and it worked fine (but I disconnected the 74138).

Couldnít find any alternative 3-to-8 chips so I bought some 7404 inverter chips today. I can invert the output from the 74138 so 7 are off and only one is on. I will test that tonite.

I tested the 74138 standalone for one fixed address setting. Used my DMM to see that 7 outputs had +5V (actually around 4.7V) and one had close to 0V.

May 20

Well, blew up the other Picaxe last night. Same deal as before, went dead when I tried to download a new program. Hooked up to the 74138. This time no LEDs involved. Had the 74138 hooked up to a 7404 chip (6 outputs). Need the other 7404 for the final two outputs.

Measure current draw for the Picaxe and 74138 and it looked to be in the 10-11ma range. The LED attached to the Picaxe drew 10ma by itself.

Checking the Picaxe forum today suggests that the download may work using batteries as the supply, and at a lower voltage! I will try tonite.

In the meantime, Iíve ordered three more 18A chips from Peter Anderson.

Very depressing. Fingers crossed for the battery test.

2 x 2 matrix

Test 2 X 2 lamp matrix driven by the Picaxe. Built this before building out for a 7 x 4 matrix.

Picaxe breadboard

The Picaxe breadboard. Picaxe connected to 74HCT138 to 74HCT240 to ULN2803 to matrix lines and TIP102/TIP107 transistors. This is for the 2 x 2 matrix. Final is 7 x 4.

May 26

Tested the 74138 and 7404 chips standalone. Also got a tip that the 74240 chip would act as an 8 bit inverter (better than 7404). I half knew that but it didnít stick. I had some 74HCT240s from Great Plains, so I wired that up and tested ok. It should work as an inverter so I donít need to use two 7404s.

One thing I found was that Phillips 74240 pin assignments differed from Fairchildís! Didnít think that should happen but I guess it does.

Still receiving comments and suggestions in the Picaxe forum. Peter Anderson threw in a 7805 chip with my order. Havenít received it yet.

Bought a big breadboard so I have one empty one to play with.

Wired an on/off switch with my power supply. Read about ground loops and avoiding them. I had my power supply plugged into a different outlet than the computer Ė perhaps that caused a problem. Now with the on/off switch I can plug them into the same power bar. But then again it is a two prong hookup Ė ground plug not involved?

Bought 74HCT138 chips to use instead of 74F138. I think the power requirements will be less.

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Last updated: September 26, 2008


© Terry Cumming, 2004-2008