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HOWTO-Make-Your-Own-ECU-Communicate-with-TCU.md

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rusefillc 2024-02-10 23:44:32 -05:00
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HOWTO-Make-Your-Own-ECU-Communicate-with-TCU.md
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TL,DR: notes on PG35 TCU Man-in-the-middle research.
Saturday Feb 10 2024 status: stock ECU, man in the middle, I substitute all torque numbers from ECU with TPS-based approximation (and TPS does not really mean thus torque does not really mean)
In the end with me producing all nine MOTOR_xxx packets TCU engages reasonably well while on jack stands but TCU outputs are really confused.
Tomorrow I will take steps back and record traces of same exact experiments with more different versions of the script, not just 'no substitution' and 'full substitution'.
As of Feb 2024 it has been _years_ since I've on and off started to work on getting an open source ECU to communicate with a transmission control unit via CANbus. So far I have not accomplished the goal which makes it a great point to write an article on the subject!
I have a [2006 Volkswagen Passat 2.0 Turbo GDI PG35 non-DSG automatic complete running and driving test mule](https://rusefi.com/forum/viewtopic.php?f=2&t=1631) idling on rusEFI open source ECU. Attempting to engage transmission while posting only minimal dashboard CANbus messages causes something violent to happen and the engine would usually stall see https://youtu.be/rTobt4l-iEs
@ -64,3 +68,35 @@ https://github.com/rusefi/rusefi_documentation/blob/master/OEM-Docs/VAG/2006-Pas
Nice! TCU reports an error now! We've learned that MOTOR_5 0x480 is required.
Manually resetting codes gets old really quickly so I have a second Proteus constantly checking if there are error codes to reset https://github.com/rusefi/rusefi/blob/0bcf342976951a24c9e81a3524e0c897b29e5440/firmware/controllers/lua/examples/vw-tp-tcu.txt
Repeating same procedure while dropping each packet ID one by one we get to https://github.com/rusefi/rusefi_documentation/blob/master/OEM-Docs/VAG/2006-Passat-B6/HOWTO/script_4_explicit_list_of_allowed_packets.lua which
explicitly mentions all the IDs allowed to pass, and drops everything else.
## Let's produce our own packet!
MOTOR_1 packet contains 🔴 a few torques which I do not know how to approximate 🔴
Let's start with very poor approximation
```language=lua
fakeTorque = interpolate(0, 6, 100, 60, tps)
engineTorque = fakeTorque * 0.9
innerTorqWithoutExt = fakeTorque
torqueLoss = 20
requestedTorque = fakeTorque
```
https://github.com/rusefi/rusefi_documentation/blob/master/OEM-Docs/VAG/2006-Passat-B6/HOWTO/script_5_fake_torque_motor1.lua
## Let's produce _all_ MOTOR_xxx packets
https://github.com/rusefi/rusefi_documentation/blob/master/OEM-Docs/VAG/2006-Passat-B6/HOWTO/script_7_fake_torque_motor1.lua
🔴 I've made a mistake of not running same wheel spinning scenario on each iteration and not recording CANbus traces and not looking at those traces. I was just focusing on "IS_ERROR" not on actual TCU outputs 🔴
Test scenario: engine is running in P, engage R, engage P, engage R, engage P end test.
https://github.com/rusefi/rusefi_documentation/tree/master/OEM-Docs/VAG/2006-Passat-B6/2024.02 has script-1-stock-ecu-reverse-twice.trc and script-7-stock-ecu-reverse-twice.trc
``java -jar reader/build/libs/reader-all.jar "C:\stuff\rusefi_documentation\OEM-Docs\VAG\2006-Passat-B6\2024.02" -filter reverse -dbc opendbc/vw_golf_mk4.dbc``