Hello Guys!

I have the YourDyno Software now ca 3 Montas. I like it reallye but when i set the Gear ratio with the Motor RPM correct by 2000U/min and i make a run it is by RPM 4000U/Min not 100% correct. 

I think it is because i have a 44 teeth triger wheel. But i think it bekoms enoth Impuls 

I drive on a Bosch FLA 203 Dyno. 

When i make a run it has deviations of approx 5-10kw.

Need i make the MOI Setup every run or just every car?

Yes, that is possible. In fact there is hardware support for only triggering the interrupt every x pulses. But with faster pulses it is better with a push-pull sensor (which some encoders do have). The standard is a pullup inside the YourDyno box, and the sensor pulls down, so it limits the max frequency of stable signals. People are extending the cables, and do many things... so I have not enabled this option to encourage lower PPRs.

Thanks for the quick reply, yes it seems to get unstable as the rpm increases. It's the factory fitted sensor on a 2001 Mainline MDX dyno, a rotary encoder. I will make a pulse modifier to divide the pulses, however I was curious if you were running an ISR for the RPM trigger event, if putting a pulse dropping option would help people with similar sensors, just a basic counter to say ignore 3 of every 4 pulses or a set value. Perhaps not enough people would have this problem to warrant implementing the code, or perhaps even triggering the isr that often is too much? explained in code below:

.. to divide the pulses by 4.

RPM_ISR

{

pulsedrop++;

if (pulsedrop != 4)  break / exit isr

pulsedrop = 0;

do rpm calcs.

Cheers, Glenn

20kHz is too much. I recommend absolutely max 5kHz. There is no point to go over 200Hz for the lowest RPM you care about. The highest RPM will then give you about say 500-1000Hz. You risk the CPU being overloaded with too high pulse count. 

@admin Hi is  there a MAX amount of pulses? I have a sensor that outputs 250 pulses per revolution on my roller (0.7m circumference) close to 20khz at 200km/h. Is this too much? I'm just working out the bugs in the system, it seems to work OK for the most part, but wondering if there is an upper limit? Thanks

@glennt

How did this work out?

Im looking to do the same.

Do a quick calculation to double check you have at least 200 pulses per second at your lowest RPM of interest. 

No problem...glad I could help.

 I looked at the brake and saw there  was holes in it for magnets. So I'm going to order some magnets. Thanks for saying that otherwise l had missed it 😂

Best regards 

Glenn 

Glenn, that brake had a magnet in bedded in the aluminum for the original sensor.

Hi, 

The RPM sensor should read the brake RPM. You do not need an engine RPM sensor, engine RPM is calculated from the brake RPM and the gear ratio. 

You can add an engine RPM sensor or use OBD2 in addition to the brake RPM sensor if you want. This will automatically calculate the gear ratio. All systems need a brake RPM sensor in any case, the brake RPM as the basis for all calculations. 

My water brake is connected at the gear box output and i run it in 4 th gear , so my rpm pickup will not read the engine rpm , how can i compensate it by software ?

thanks in advance

Fabrice

Any number that ensures at least 200 pulses per sec at the lowest rpm of interest will work. More is good. 

So for example 15-20 or so. 

BTW, how many pulses does your system expect per one turn of dyno shaft (in case of engine dyno configuration)?