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-   -   Brake pressure PID? (https://www.ft86club.com/forums/showthread.php?t=123637)

ChrisW 11-26-2017 01:00 AM

Brake pressure PID?
 
Has anyone found the PID for brake pressure? I'm hoping to be able to log it with an OBD2 app and not need to get it via USB from a tuned ECU.

gcranston 04-17-2018 08:37 PM

I would love to get this working as well. Aim can see it. Has anyone figured this out? OP are you using torque?

n0thing 07-23-2018 08:20 AM

bump

I've logged brake pressure, steering angle and individual wheel speeds using OFT, but reviewing the data and overlaying them on videos takes a lot more work. Ideally I'm looking to do so via Racechrono/HLT/Torque. Or are those values limited to CAN mapping only?

treedodger 07-23-2018 12:52 PM

Harrys Lap Timer (HLT) supports custom PID in their Beta V22 release, but I haven't figured out how to capture brake pressure. HLT V22 will estimate brake pressure from accelerometer data, if a custom PID isn't used.

http://forum.gps-laptimer.de/viewtopic.php?f=48&t=4907

I found this, but not sure how to implement it:
https://forum.autosportlabs.com/view...sc&start=0

Brake Pressure/Position

ID: 0xD1
Offset: 16
Length: 8
Type: Unsigned
Endian: Little
Multiplier: ???
Unit: ???

I have not quite deciphered the brake unit conversion yet. I have seen values of 0-120ish in practice. This is likely limited to just how hard I can press down on the pedal. This may be a position or pressure value.

HSV Guy 10-24-2019 10:46 AM

Bump, anyone been able to get this setup via an OBD dongle? Would like to use this, if possible, with Harry's Lap Timer (HLT).

treedodger 10-26-2019 03:23 AM

Quote:

Originally Posted by HSV Guy (Post 3269306)
Bump, anyone been able to get this setup via an OBD dongle? Would like to use this, if possible, with Harry's Lap Timer (HLT).


I never got this to work and those OBD signals I did get were out of sync and HLT tools for fixing this would a waste of time (circa 2018).

I gave up and bought a Aim Solo 2 DL.

timurrrr 07-15-2020 08:30 PM

Couldn't read the brake pressure via OBD, but at least was able to read pressed/released.
Better than nothing, at least should be possible to see braking points lap vs lap.

In RaceChrono, I use
0x7E0 for "OBD-II header"
PID 0x221233 for brake pressed/released (Mode 22, PID 0x1233?)
PID 0x22122F for clutch pressed/released
Equation: B / 2.55

Compelica 07-16-2020 02:49 AM

Quote:

Originally Posted by timurrrr (Post 3349576)
Couldn't read the brake pressure via OBD, but at least was able to read pressed/released.
Better than nothing, at least should be possible to see braking points lap vs lap.

In RaceChrono, I use
0x7E0 for "OBD-II header"
PID 0x221233 for brake pressed/released (Mode 22, PID 0x1233?)
PID 0x22122F for clutch pressed/released
Equation: B / 2.55

Thanks @timurrrr, how are you obtaining these PIDs? Would be much easier to log them using Torque than pulling Tactrix at times...

RRslip 07-16-2020 04:35 PM

I take brake pressure from CAN ID 209 (decimal), offset 2, length 1, unsigned, little endian. No equation needed. I think it's in Bar.

timurrrr 07-16-2020 06:07 PM

Quote:

Originally Posted by RRslip (Post 3349819)
I take brake pressure from CAN ID 209 (decimal), offset 2, length 1, unsigned, little endian. No equation needed. I think it's in Bar.

I believe you're reading it from CAN directly? Not from OBD-II, which is the topic of this thread.
How to read it from CAN has already been mentioned above.

Which device do you read it through? Can you send it to RaceChrono/HLT via Bluetooth?

RRslip 07-16-2020 06:37 PM

Quote:

Originally Posted by treedodger (Post 3113378)
Brake Pressure/Position

ID: 0xD1
Offset: 16
Length: 8
Type: Unsigned
Endian: Little
Multiplier: ???
Unit: ???

I have not quite deciphered the brake unit conversion yet. I have seen values of 0-120ish in practice. This is likely limited to just how hard I can press down on the pedal. This may be a position or pressure value.

I thought I would shed some light on the multiplier and unit. I'm using a RaceCapture Track MK2 which does PIDs and public CAN.
https://www.autosportlabs.com/produc...turetrack-mk2/

Compelica 02-13-2021 08:55 AM

Just wanted to bring this up - the OBD Fusion app with the extended parameters has the brake pressure PID, which works well but the app is a little slow in responding. Would have preferred to port the PIDs to Torque which has much more flexibility, but at least there's the option for us FRS/86/BRZ owners.

timurrrr 02-17-2021 03:03 AM

Do they show which PID they use?

Also, which car did you test it on? FR-S, BRZ or [GT]86?
Those "extended parameters" are typically manufacturer-specific, and they consider Scion, Subaru and Toyota to be very different manufacturers.

Compelica 02-17-2021 05:36 AM

Quote:

Originally Posted by timurrrr (Post 3407223)
Do they show which PID they use?

Also, which car did you test it on? FR-S, BRZ or [GT]86?
Those "extended parameters" are typically manufacturer-specific, and they consider Scion, Subaru and Toyota to be very different manufacturers.

I doubt it is different - I expect it to be universal across the models, given that the tunes for the 3 models are basically the same apart from some regional differences. For example my car is a JDM GT86 running a tune for Australian 86/BRZs with the OBD Fusion app set as a Scion FRS.

On getting the actual PID addresses and formula - unfortunately that's hidden away as getting those extended PIDs is a paid feature. You can only select it but not manipulate how it is calculated since it could be easily copied out.

On the other hand if we had someone able to do some RE we can probably make some progress...


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