applet.interface.freq_counter: implement basic frequency counter #218
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re aliasing: With a ~44.1kHz input, we'll typically see one of the following two outputs over a 131072 clock period (@48MHz = 2.73ms). I've thought about this a little more... the resolution of the output is the sample period (or its frequency).
From here we get diminishing returns, so I think I'll set the default duration to 2 seconds, for a 0.5 Hz resolution. I might also present the resolution or error for the measurement in the output. |
The ripple counter's length is essentially unlimited, right? (Limited only by FPGA size.) So you can make something obscenely large, like a 32 bit counter, and run it for a second or even several seconds. That's like averaging you suggested on IRC but with less work. |
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Yes, correct. I'm planning to make the sample period configurable at runtime, but with a default of 1-2 seconds to help improve this. |
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This commit is work-in-progress: - Create `FrequencytCounterInterface` class - Add duration command line argument - longer run offers higher resolution - Clean up output
As discussed in
#glasgow, this PR will implement a basic frequency counter, based on a ripple counter, paired with using the Glasgow's clock as a time reference.This commit is work-in-progress:
FrequencytCounterInterfaceclassNOTE: This PR differs from #216 - that is providing more complex (but still basic) signal analysis, while this provides a pure frequency / edge counter.