As part of our first public meeting this Monday, we handed out a bunch of :CueCats to everyone who attended, along with a challenge: tinker with them, see if you can get them to do something fun, and share it with everybody at the next meeting.
I’m planning on using mine to build a handheld barcode scanner based on an Arduino and the touch screen from a Nintendo DS that stopped working a while back. It may be a bit ambitious, so I’ll probably need help along the way. I thought it might be helpful for others to see what I’m doing in case they get stuck in their own projects. The Arduino is in the mail, but while I wait on that, here’s the progress so far.
The devices we passed out were model #68-1965-A, rev. 06A00. These are all PS/2 models, so there’s a bit more of a challenge involved if you don’t have a computer with a PS/2 port and a non-USB keyboard.
Upon removing the case (4 small Phillips screws in the base and 4 even smaller ones on the PCB), I discovered that these must have been late-model 06A00’s, since rather than the chip shown in most pictures online, there was a blob of epoxy more commonly seen on the 07A00 series devices.
The back of the board has a connector for the PS/2 plug, but unfortunately it isn’t removable, so for the moment, I left it alone. The variable resistor apparently adjusts the scanning speed, but I haven’t tried changing the setting yet.
After a bit of searching online, I found that even thought the IC in the center of the board may have changed, most of the other circuitry was the same as the old model, so disabling the serial number for this device was as simple as cutting a single trace so that one of the pins of the IC just below the U6 label on the board floats. I just used a utility knife, it doesn’t really take much.
This is the output from the scanner, both before and after cutting the trace above. I ran it through a simple perl decoder script because I haven’t wired up the device to do the decoding yet. As you can see, after cutting the trace the serial number no longer appears in the output.
The next step for me is to get the device to decode the barcode string before it outputs it to the PS/2 line. cexx.org indicates that by this can be accomplished by tying R6 high from any of the +5V lines on the board, so I’ll give that a shot. (Thanks to Kevin R for pointing that out!)
Hopefully my Arduino will arrived in the next few days and I can start moving forward with the next stage of the project!