Originally Posted by
Tom H
My current working assumption of the module pinout is:
PIN 1 +5V
PIN 2 ANALOG OUT (LEVEL)
PIN 3 MODULE ID
PIN 4 +10V ANALOG
PIN 5 KNOCK DETECTED
PIN 6 GROUND
PIN 7 INPUT
PIN 8 N/C
I had expected (based on some patents GM holds) that a "KNOCK WINDOW" signal would be sent into the part to define the detection window. This isn't the case (I think) and if windowing is used, it it all inside the TPU. Re-considering the system, this is probably for the best.
So that revises my guesses: Analog out is used to determine module and sensor are there only (?). Long path for this... analog out is measured by the A/D on Tside and passed to Eside through SPI. Again I think this is only for monitoring that the components are there and working. Knock detected is set when filtered levels of the knock frequency are at some threshold above the noise. Knock detected is counted by TPU when inside a knock window (?). +5V and Module ID are there only for manufacturing and test (?). Input comes from a pre-amp on the Tside (96/7 at least). Should two knock sensors be used as an option, there are some controls into the pre-amp. The two signals are combined there.
One other possibility for knock window in the system is that TPU pin 11 is routed through the ribbon (pin 25). The gain of the pre-amp might (?) be modulated OR the output zeroed .
Lots of things to check through. While I am trying to figure out how to simulate the knock sensor, there are tests to see how the TPU responds to knock out that can be run.
-Tom