Welcome to Robot Dialogs. This is a place where I will record my progress, mistakes, errors, failures, lessons learned and hopefully occasional success in my designs and implementations of robots and other technical endeavors. I will try to make it as educational, informative and entertaining as I can...

Wednesday, August 4, 2010

GameBoy (Classic) Work In Progress Part 3

First: The Open Logic Sniffer is the best thing since sliced bread.

Second: I finally have reliable recorded data from the GB CPU to the GB LCD.


Okay so before making sense of the data here's what you need to know. I clocked the GameBoy CPU with my own micro-controller the resulting GameBoy CPU Frequency was 812 kHz. That's 24.63 times slower than normal (20 MHz), so all of the data collected needs to be time scaled appropriately.

The data was collected on Pins 12-19 of the ribbon cable between the CPU board and the LCD board (See previous post for pin numbering and pin names, some of which are guessed). These pins correspond to inputs 0-7 on the logic analyzer respectively (see labels on image above if you're confused).

Two of the data sets were sampled at 10MHz and one at 1MHz. The 1MHz set was only taken for timing of the Vblank (it isn't a high enough sample rate to be considered accurate for data analysis).

I won't be drawing conclusions about the data just yet, for now I just want to make it available.

To get the data go here: GB Data 2.zip I'd be happy to collect more, just leave a comment.

To view the data go to The Gadget Factory and get the JAVA Client. It's Free. Run the executable (it doesn't install, it just runs a JAVA program) and then open one of the ".sla" files.

It's too late to code it up tonight, and I'm building a new PC tomorrow so hopefully this weekend I can get it working.

As a side note, I am really pleased with the Logic Sniffer. I had it out of the box, firmware updated, and got this data collected in less than an hour. I highly recommend that you consider getting one.