Spartan 3-AN Starter Kit Amp and ADC Controller

About

This module is designed to interface with the Linear Tech LTC6912-1 programmable gain amplifier and LTC1407A-1 dual 14-bit ADC converter available on the Spartan 3-AN Starter Kit. It is essentially a minimal SPI core that both programs the amplifier and interfaces with the ADC for repeated captures.

Using the module

Interfacing with this module is very simple. Hook up all of the appropriate signals (see the comments in the file) and control it as follows.

  1. Start by providing a reset pulse of some duration. I found that 64 clock cycles at 50MHz worked well. If you don't, the pre-amp hardware doesn't settle correctly.
  2. When you are ready to program the gain, load the pre-amp gain into the gain bus, and then pulse amp_cfg for one clock cycle.
  3. Wait for amp_done to go high. Now you can begin sending ADC conversion requests whenever you want.
  4. To get a sample from the ADC, pulse start_conv for one clock cycle and wait for to go high. At this point, the signals adc_a and adc_b will be valid until the next conversion request.

Eventually I may add support for continuous gain control, but for now you can only set it in the begining.

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