KIWI OBD not working very well in version 16

gplracerx · Post by **gplracerx** » Mon Aug 20, 2012 2:17 am

Actually there seem to be a lot of bugs in version 16, but this was the worst. None of the five runs I recorded this Sunday at an autocross had decent OBD data for throttle, speed and RPM, or at least it didn't show up on the charts. I haven't looked at the csv file yet. For RPM's and speed I got a bunch of spikes on the chart. It also seemed to have a problem linking to the external GPS. Only one of the five runs was recorded using the external GPS. One time didn't count as I accidentally unplugged the Emprum dongle at the beginning of the run. But that still makes three out of four runs on the internal GPS rather than the external unit. I didn't have this problem with version 15.

Other problems include losing the banner in landscape mode so no way to switch the view from map to charts to laps without rebooting. Sometimes even when you could see the tab bar at the bottom, touching the buttons had no effect. After recording one video, I gave up on landscape view entirely. Autohiding the tab bar may be the problem.

More later.

gplracerx · Post by **gplracerx** » Mon Aug 20, 2012 3:10 am

I've looked at the .csv and the .hlptrl files. What good does it do to specify a high sampling rate for the accelerometer if you only get the data in the files at points where there was a valid GPS fix with large and variable time gaps between those? What I want to see is ALL the data. The Sensor Data app does just that, but unfortunately doesn't talk to the OBD device. I also see a lot of zeros in the OBD data columns. No wonder the rpm and wheel speed plots were spiky. In the GPS window before a run, the throttle and rpm graphics seemed to work just fine. In the expert settings under OBD Tweaks, there are several new settings: Throttle PID, which has choices default, and positions B to F, Pause between PID's, which has a default setting of 0.01, Custom Host and Custom Port. Do I need to set the host and port to the same values as the Kiwi device or what? There are also custom host, custom port and connection type settings in the GPS tweaks.

Post by **Harry** » Mon Aug 20, 2012 7:43 am

Hi,

There are no known bugs for OBD with the kiwi, actually the code has not been changed in this area... Are you sure you had everything connected correctly and no other wifi disturbed the connection?

The landscape / rotation thing is indeed a known bug and will be fixed in version 16.0.3 (16.0.2 is in Apple review currently). To work around it, change the device to landscape BEFORE entering the video view, thus getting the recalibration dialog outside the video view. In case you run into th situation again, send LT to background and kill it using the task bar.

Harry

Post by **Harry** » Mon Aug 20, 2012 8:36 am

On acceleration: high rates improve both the real time experience, and data quality of the stored data: LT always stores the max value between GPS fixes, so higher update rates are beneficial to not lose peaks.

Harry

Post by **Harry** » Mon Aug 20, 2012 5:58 pm

This post made me think about the dropped OBD fixes in relation to high update rates for acceleration. Without going too deep into the programming it is indeed a problem when 100 fixes per second coming in from acceleration. LT uses several buffer chains and having acceleration set to 100, they push out OBD fixes from time to time... So please reduce the update rate to e.g. 50 (or stay with the 30 default) and OBD drops will most probably stop. I will increase the buffers to a higher number in 16.0.3

- Harry

Post by **Harry** » Mon Aug 20, 2012 6:01 pm

Finally, please do not touch the expert settings if not necessary. The kiwi does not require any setting here - except for BMW drivers that need to switch throttle to D instead of the default.

Harry

gplracerx · Post by **gplracerx** » Tue Aug 21, 2012 1:56 pm

I suspected the OBD data problem was caused by using the maximum acceleration data rate. The GPS problem is more complicated. If I look in the .csv output file, the Emprum data are there, but in the data recording section of HLT for the lap it says: GPS Sensor Internal @0.0 Hz or 1.0Hz. So apparently I need to perform a check list before starting a run: Go to the GPS page and see if the data rate is ~5 Hz, go to the acceleration page and fix the calibration by reorienting the device to lateral and lineal equal to zero (and hope the yaw isn't too far off) and then drive the car to the starting line.