pcmhacking.net

You're getting some great results there
Logging the knock filter as an analogue voltage is never going to be a great solution (as you've found out) - but I guess it can't be too bad because it's doing a decent enough job.

I can log it as a digital input if that's going to make it better?

I don't think that will make it any better.
Using either an analogue or digital input, each time the ALDL message is sent the ECU reads the current state of the input and sends the result (on/off for digital or a voltage for analogue).
But as you found, the ALDL messages are being sent at a minimum space of 70ms.
There could be 50 knock events between two messages, but if the input was off at the instant that the ECU read it then it shows up as no knock.
By setting the "knock sustain" to around the time between tow ALDL messages (70-120ms), it pretty much makes sure the knock event is logged.
That much knock sustain isn't much good if you're using the filter module for ignition control, but in your situation it's a good solution.

I understand the 808's knock input pin is a counter, so rather than the state of the pin being read and sent in the ALDL message, the ECU increments a counter every time the pin's state changes and that number is what's sent - so having a long knock sustain duration wouldn't be a good idea there.

The old Bosch Motronic ECUs I've been playing with have no knock control, but they do have high/low octane map selection from an external pin (like 12P's map A/B selection).
With these ECUs, this knock filter could be connected to the octane pin and everytime knock was detected it would switch back to the low octane maps for the duration.
By setting the knock sustain to a suitably long period, the timing would be backed off when knock started, and would switch back after the knock sustain time was up.
it's not a perfect solution, but gives basic KR without having to modify the ECU or maps at all.

what is the problem your trying to solve? does 12Ps knock count logging not help?

No, 12P is fantastic - the problem is logging it on other ECUs that don't have a counter input that can be used.
VX overcame it by changing a setting on the module to keep the knock signal active long enough for it to be picked up.
He had a LED indicator connected and was seeing the knock there, but it was too quick to be logged to start with.

most people would have knock ears on when tuning anyway and would hear knock before it triggers the knock sensor

The digital inputs of the logger are counter inputs, they measure freq or duty cycle. Might be able to have the option so it accumulates and gets reset after the aldl packet has been sent.

If anyone is interested in one of these knock modules, I've got a small number for sale.

Please put me down for one.

im keen mate