Input edge triggering
Add a firmware edge-triggering capability.
- Sample continuously, but do not buffer, until an edge crossing is detected.
- Then buffer and push a sample frame.
- In the absence of triggers for a while (~500 ms), push a sample frame anyway, unless in "single" mode.
- Make it configurable via USB.
Add a "single capture" mode configurable via USB.
- When this mode is requested, start capturing (if paused); push the next triggered frame; then stop capturing.
Some external ADCs also have "voltage alarm" features that could be usable in this capacity.