That's what I was asking about :)

Anyhow, WE DID IT!
In RaceChrono format, the parameters are:
Channel: Brake Position (%)
OBD-II header: 0x7B0
PID: 0x2141
Equation: min(100, 1.1 * max(A-10, 0))

Explanation: the min/max trick makes sure the output is in the [0%, 100%] range. The 1.1x is a multiplier that roughly matches the scale factor I previously chose for my CAN bus reader so that 100% is reported when I'm braking really hard. The -10 offset is to compensate for the default value of 10 (I've no idea why the reported value never goes below 10).

Enjoy!

Having said that, OBD-II provides a much lower refresh rate than CAN, so I still recommend investing a little time into making a DIY CAN reader as documented on my GitHub:
https://github.com/timurrrr/RaceChronoDiyBleDevice

Nice!

To add on - the brake pressure PID visible in the app shows in two units: by MPa and by voltage. And in the voltage there is always a value (about 0.1v if I'm not mistaken) even when the brakes are untouched so it correlates back to your compensation. However the MPa value does go from 0 to 10 MPa - this is with me lead-footing the pedal :)

Would you have any insight on how to implement this on Harry's Lap Timer Custom PID Menu? The requested inputs are pretty different compared to what I've seen here and am used to.


Developer guide: http://www.gps-laptimer.com/LapTimer...%20Program.pdf



The input menu asks for

• Channel
  • Lists a bunch of available channels that HLT records to. Not particularly important, just the column in the default CSV that the application records to
  • I would map it to "Brake Pressure [kPA]" and scale it to % in post processing
• ECU
  • Defaults to "ALL" for functional calls
  • States to address a specific ECU if desired for physical calls (such as "ECM" or "TCM"), or when using custom mode $21, $22, $23 below
• Mode
  • Mode 1
  • Mode 9
  • Mode 21
  • Mode 22
  • Mode 23
• PID
  • 1, 2, or 3 byte hex strings
• Request Frequency
  • Low
  • Medium
  • High
• Formula
  • Basically C-language logic, similar to what was used in RaceChrono implementation

-------------------------

My best interpretation of the inputs that would work in HLT would be, with some feedback from the developer on a similar implementation [ http://forum.gps-laptimer.de/viewtopic.php?t=5589 ]:

• Channel: Brake Pressure [kPA]
• ECU:ECM
• Mode: Mode 21
• PID: 41
• Request Frequency: High (probably doesn't matter from a functionality point of view)
• Formula: =MIN(100 : (1.1 * MAX((A-10))))

Obviously, it doesn't have field to input a custom header like I'm used to seeing in applications like Torque (and RaceChrono). However, there is a way to specify a custom width for the parameter by adding leading zeroes. For example, specifying the PID as "41" allows it a width of 1 byte, but if we instead label it as 0041, it will be 2 bytes wide. Perhaps this is the way to incorporate the header?

Try ECU: 0x7B0.

If that doesn't work, you may want to ask on the HLT forum.
I know how to enter the config in RaceChrono and what underlying messages are sent over the bus, but never tried HLT, so don't know what format it wants for the OBD PID or ECU CAN ID.

Or you can try the superior CAN bus mode in RaceChrono :)