Re: OneROM emulator Datlogging Vx-vy

[Muncie]

I’m starting to look at the logging side of the OneROM setup now that the VT and VX/VY live-tuning side is working reliably.
The current VX/VY setup is:
TunerPro → Ostrich protocol → Fire32B / OneROM → PCM
and that part is now working very well for live calibration changes.
The next problem I want to solve is logging without relying on the external ALDL/OBD connection.
On the VX/VY V6 PCM, the external ALDL line is:
PCM F14 → DLC pin 6
What I’m hoping to find is the logic-level TX/RX side inside the PCM, before the factory ALDL driver/transceiver circuitry.
The aim would be something along the lines of:
PCM internal UART TX/RX → simple level protection/conditioning → Fire32B UART → USB
This is similar to what some Honda OBD1 OneROM users are doing with the ECU’s internal serial header and a small resistor network.
I’m specifically trying to avoid connecting the raw vehicle-side ALDL line directly to the Fire.
Reasons for doing this:
remove the external ALDL interface and second USB connection
keep the vehicle diagnostic bus as undisturbed as possible
eventually have live tuning + logging through the same OneROM connection
later feed the same data into an ESP32 / dash system
On my turbo VY, logging through the normal ALDL/OBD setup has occasionally coincided with traction-control communication issues, so getting the logger away from the vehicle bus is becoming fairly important.
I realise tapping the internal UART will still leave us with the normal 8192-baud ALDL bandwidth limit initially. That’s fine for the first stage. Longer term I’d like to experiment with a separate custom telemetry stream from the PCM so the factory ALDL bus isn’t the bottleneck at all.
Has anyone already traced the VX/VY V6 ALDL circuitry from F14 back toward the CPU?
In particular, I’m looking for:
CPU/logic-side TX node
CPU/logic-side RX node
logic voltage
polarity
whether TX/RX remain separate internally before being combined onto the single-wire ALDL line
any known transceiver/driver IC or transistor stage involved
If this has already been scoped or mapped, it may save me reinventing the wheel.
If nobody has the information, I’ll start tracing it on one of the OneROM VX/VY PCMs and post the results.