Friday, March 04, 2005

DSOs and Compilers

Still finding time here and there that I feel I can code. So, some new things I've drummed up or run across.


I still would like to build a DSO for my computer eventually. For this, I came up with a different method that may still be compatible with the original Bitscope. Instead of using a CPLD to feed SRAM data from a ADC, why not use a FIFO? TI sells a nice reconfigurable one that'll be useful for porting data anywhere from 8 to 16 bits wide into an 8 bit serial port on a PIC. The 64K/128K buffer is about the same as available on the bitscopes. I may configure it to have an 8 bit ADC and an 8 bit logic capture, or maybe a 12 or 16 bit ADC. I like both options, maybe I'll build both. I can run the FIFO up to 167MHz, far exceeding the capture rate of the Bitscope, but I lose the Bitscope's flexibility and mode triggers made available by the CPLD. Still might be a good project, especially since I don't have to run it at 167MHz. A USB PIC can live on the output end of the FIFO to provide a USB control and transfer interface to a PC. If I build it with a slower 16 bit ADC, I might consider using a dsPIC and doing a live digital filter or micro-based SRAM transfer instead.

As for Oscillopen? I'd like to try to fit it all into the format of a fat marker, and either make it battery powered or a USB port on the far end with either a single BNC or similar connector on the input end.

Free Compiler

Wll, Microchip's at it again. They've released their C18 C compiler for the 18F series for free now. Sorta. It's the student edition. It will stop being it's most optimized after 60 days IIRC, however, it will continue to work. Win win situation for hobbyists in my opinion. If you need better speed and smaller code, go assembly. I still plan to code my R/C core in assembly first, as a learning experience.

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