[Christian Weichel] has been hard at work developing LogicAnalyzer, an open source tool that may interest you. It is designed with SUMP Logic Analyzers in mind but a main goal is expandability. What this means is that it plays nicely with things like the Open Workbench Logic Sniffer or you can do a bit of fiddling to get it to work with your own designs. The program is based on Eclipse so you should be familiar with how it works and you can get it running easily on multiple platforms. Take a look at the wiki for a quick start.
In a two-part series called “PS3 Fab-to-lab” on IBM’s awesome developerWorks website, [Lewin] explains how to use the Cell Broadband Engine in a PS3 to create an audio-bandwidth spectrum analyzer and function generator. The set up consists of Yellow Dog Linux, an NTSC television, and an external USB sound card to provide the inputs of the spectrum analyzer and the outputs of the function generator. The sound card driver is written to simply capture or send the info in question (audio range only) and the NTSC television as the graphical interface. This hack involves a lot of coding with hardly any example code provided. The article is more of a guide than anything. If anyone gets this working, let us know!
[photo: Malcom Tredinnick]
As promised earlier, the Near Future Laboratory has published an overview of the Logicport Logic Analyzer. They’re using the Playstation 2 analysis as an example. The Logicport uses “interpreters” to define protocols. It has I2C/TWI, SPI, RS232, and CAN 2.0A/2.0B, but you can build your own interpreter based on these. You can specify bit order and the format you want the data in. Slave interpreters can be used for specific tasks: with the PS2 they were used to just show the fifth byte, which is the actual button press.
“Triggers” are used to signal specific activity. On the PS2, one was attached to the falling signal on the slave select line. This event means the master is about to start sending data.
The final area worth exploring is “measurements”. These can be frequency or arbitrary time intervals between events. The Logicport has multiple ground connections to eliminate noise from the signal and you’ll have to play with sample rate and logic level to get things running smooth. It’s nice to see how-tos written from the perspective of someone just getting started with the tool.
The people at Near Future Laboratory are trying to spoof the behavior of a Playstation 2 controller using just a microcontroller. They wrote some initial code using the controller info found here, but decided the best way to figure out what was going on, was to probe the interface. They’re using a Logicport, which features 34 channels plus two clock channels. They only need six channels because the PS2 implements an SPI protocol plus an ACK line. The post is just a preliminary investigation, but will give you a little insight into how the Logicport works and why you might find it useful.