Bad resolution in OBD-II speed

MikeGolf

Hello,

I use RaceChrono for a long time and i like it very much. But since i have upgraded to pro version it seems to work slow on ODB data. I use the same android smartphone, the same ODB device and the same gps receiver. i have tried all different ODB settings, i have removed unnecessary channels but it wont be as fast as before. I have made a screenshot to show what i mean. you can see the speed from gps and ODB. The ODB speed looks like stairs, and all the other ODB data would be slow too. But at recording time ist say about 4 fps. I don't know how to solve the problem. Hope you have some ideas or suggestions for me.

Screenshot
https://www.dropbox.com/sh/gjl36ip7w3mi6kz/AAChe5kbwOTjOkaHbdvH0t5Ya

regards Gerhard

aol_of_RaceChrono

Yes, that doesn't look right. Looks like the refresh rate is very good (from the reader), but it's getting same data from the ECU for many updates in a row, making it only 1 Hz.

RaceChrono Pro and Free has same OBD-II code so it's not that. But I did make some changes to it during the summer. Also are sessions of both of the screenshots recorded with same setup OBD-II reader + Vehicle?

Please turn on RaceChrono > Settings > Expert settings > Save device output. Then run a new session with OBD-II connected to the car. You need to drive around a bit to capture some changes on the speed. Then you should have device_output_*.obd file in the new session's folder. Email that to tracks(at)racechrono.com so I can see what's wrong.

Please use default expert settings for OBD-II, which are Protocol: 0, Slow channels - Unchecked and minimum delays.

MikeGolf

I have sent you the device_output_*.obd files. Hope you will find the bug. My last working session was from 21.06.2014. The next session i recorded was on 15.07.2014 which has the update problem. I have used always the latest RaceChrono version from google play store but i don't know the exact program version.

PS: Yes the same setup ODB-II reader and vehicle ... i can send you more data if you need

regards Gerhard

aol_of_RaceChrono

I made an OBD-II change in 25.07.2014 for the release version, but people in beta group received it earlier. You're a member so it all matches up.

Could you do me a favour, please log another session with only the speed channel enabled. The log you sent me gives me a clue what could be wrong, but it's still inconclusive.

MikeGolf

I have sent you the Log files with only speed channel enabled. I have added 2 more screeenshots
with the refresh rate.

https://www.dropbox.com/sh/gjl36ip7w3mi6kz/AAChe5kbwOTjOkaHbdvH0t5Ya

regards Gerhard

aol_of_RaceChrono

Fixed in a maintenance release: RaceChrono Pro v3.22 beta 1

MikeGolf

Thank you very much for your help. Your support was great ... so my trackday was great too ... Everything works fine.

regards Gerhard

MikeGolf

Hello, i am not sure but maybe i have found a small bug in the speed resolution. Update rate is good but the ODB speed values are only even numbers. e.g. 2, 4, 6, 8 km/h. Never odd numbers. Therefore the magenta line (ODB speed) has some stairs. The cyan line is GPS speed. I'll send you the device_output_*.obd, please have a look at it.

Screenshot:
https://www.dropbox.com/sh/gjl36ip7w3mi6kz/AAChe5kbwOTjOkaHbdvH0t5Ya#lh:null-2014-10-14 19.01.14.png

regards Gerhard

aol_of_RaceChrono

Your car reports the speed only in 2 km/h resolution. Probably nothing can be done about it. Notice the stairs appear only if the update rate is faster than the speed is changing. So if you improve the OBD-II speed update rate by polling only couple of channels, and maybe get better OBD-II reader, these "stairs" in graphs are more visible.

Notice the "stairs" appear with the normal 1 km/h resolution as well in similar conditions. It would require decimal values to appear smooth at every situation.

aol_of_RaceChrono

The fix to the original problem is now released in v3.30 beta 1