[sdiy] Function Generator ICs
dbetz at xlisper.com
Fri Sep 21 13:26:52 CEST 2007
> ... the development board I have (Xilinx Spartan-3E Starter Kit)
> and that the price
> was $149 with lots of goodies (RAM, flash, LCD, rotary encoder,
> DAC, ADC, etc.) on the board as
> well as a reasonably large FPGA. Bang for the buck, it's great.
> It's not an audio board - it's
> a dev board. It has a 12 bit DAC which works, but is a tad noisy
> due to a nonoptimal reference
> circuit. This can be fixed by adding your own DAC through a
> connector. The on board DAC has
> been good enough to get things done. I do MIDI stuff, so I use
> only the DAC, not the ADC. For
> MIDI, you need an optoisolator and for the output you need a
> resistor and a cap. So you don't
> have to build very much to get started. The only thing I'd really
> like to add is a 16 bit SPI DAC.
I have been doing something similar (although not nearly as far
along) using the Digilent Nexys board:
The board I bought has a 1 million gate capacity (an extra $20).
I also bought the 12 bit stereo D/A module:
For a total of $140, that gives me most of what Scott has but lots
more gates to play with. A nice feature of the Nexys board is that it
uses a USB connection to your PC to get its power as an option. When
the USB is connected, you can use a fairly simple to implement
protocol to read/write registers in your logic on the FPGA. It uses
the same Xilinx tools that Scott's board uses. Unfortunately, it
doesn't have the rotary encoder.
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