Spartan 3-AN Starter Kit Amp and ADC Controller
This RTL module interfaces 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 continuous capture.
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.
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.
When you are ready to program the gain, load the pre-amp gain into the
gainbus, and then pulse
amp_cfgfor one clock cycle.
amp_doneto go high. Now you can begin sending ADC conversion requests.
To retrieve a sample from the ADC, pulse
start_convfor one clock cycle and wait for
adc_doneto go high. At this point, the signals
adc_bwill be valid until the next conversion request.