DIY data collection (with link to working code for Arduino and Bluetooth )

DrMotor

Output temperature (or whatever) from Arduino to RaceChrono via Bluetooth Short and simple code made by DrMotor for NiNo-racing https://www.facebook.com/ninomotorracing/

Free to use, share and improve: https://drive.google.com/file/d/1mLRYEhGO13sL0eFP0sm9QtEvY1IDeYdI/view?usp=sharing

aol

Thank you for sharing!

DrMotor

Update: V0.2 https://drive.google.com/file/d/1Q1PgftHmVJHZ2RS9aPMR6TE159BLNNQM/view?usp=sharing

Changes:

Internal pull-up resistor in stead of external,
Added link to instructions for data rate
Reduced filter time constant

DrMotor

Update: V0.3 https://drive.google.com/file/d/1BrJQQi1hsWn1SMY-dmzat2M6y8sQYSM3/view?usp=sharing

Changes:

Added thermocouple (for exhaust temp) via MAX6675
Connected throttle and brake pedal sensors
Reduced update rate of temperature reading beacuse MAX6675 appears to be slow

DrMotor

I tried AT09 (BT4/BLE) module in stead of HC05 (BT2). When using "Serial Bluetooth Terminal" on my Android phone I can see data is arriving (same with AT09 as with HC05), but with AT09: RaceChrono (on the same phone) always and forever get stuck with message "Connecting to Data logger..." and "Connecting... (waiting)".

Preliminary conclusion: AT09/BLE works with my phone, but not with RaceChrono. I will continue using the HC05 and save the AT09 for another project. The Arduino/Nano is anyway too slow to take advantage of the higher speed of BT4.

lzzl551

@DrMotor Did you add rpm sensor?What type of throttle and brake position sensors are used? Can you share sensor installation photos?

DrMotor

My pedal sensors: analogue hall IC + wire + permanent magnet + 3d-printed bracket. I removed them from the kart because of FIA/national regulations (it might be OK for practice if no-one complains).

No RPM sensor yet -- it has low priority as the go kart has a single gear ratio and I can calculate RPM from speed (Bluettooth GPS).

DrMotor

@izzl551: kart pedal sensor in parts https://drive.google.com/file/d/1W8gwKLMNdZLv570sDJ2aKmE0Q_mF1aB4/view?usp=sharing sensor as used (not mounted): https://drive.google.com/file/d/1C5UVPgGk2YYrefDd_QTI3kPoB3RnuImu/view?usp=sharing I used same sensor in this e-kart: https://www.facebook.com/ninomotorracing/videos/1857248704301750/

Assembly to go kart:

clip Hall into the holder
zip-tie holder with Hall to chassis close to pedal hinge point
zip-tie magnet to pedal arm (at hinge) so that a magnet pole points towards Hall when at half throttle (or approx touch point of brake)

lzzl551

@DrMotor Very great DIY, I think rpm is very important, GPS update rate is 10-20hz, rpm update rate can reach 50-100hz, rpm curve can reflect the driver's throttle control, rpm sensor is more than the throttle position sensor important,

DrMotor

@izzl551 OK, so I move RPM sensor to top of my list -- makes sense as pedal sensors are banned. The argument against additional sensors goes like: "too expensive for karting". I is unbeliavable that a 50 cent pedal sensor should fall for that argument.

It would be easy to connect the Arduino to the crank angle sensor (the sensor is already present for the ignition system), but modifications to the ignition system are banned. Most RPM probes for karting use only capacitive coupling towards the high voltage spark plug cable -- the sensor cable goes from logger and is tied to (sometimes twisted a couple turns arround) the spark plug cable.

Do you know what circuit can/should be used for detectig the signal from such capasitive coupling?

aol

We have a race series here in Finland where data logging (including RaceChrono) is completely banned because it's "too expensive" ...

lzzl551

@DrMotor Kart sensors are too expensive due to monopoly. There are only three companies in the world that produce kart data recording equipment. AIM, alfano, unipro and AIM are monopolized. So the price is very expensive. My current idea is to replace mychron5 with mobile phones. I want to record GPS, RPM. , water temperature three data. I am looking for an rpm sensor that can be connected to arduio. But did not find a suitable solution, raceDAC too expensive. (the sensor is already present for the ignition system) I know that the ignition system is forbidden to modify. Is it possible to obtain the rpm signal from the ignition system without modifying the ignition system?

lzzl551

@aol Yes, the karting sensor is really too expensive. When I know that there is a racechrono app, I think karting data logging equipment can be very cheap. Use a mobile phone with a home-made sensor to replace Amy's mychron5。Racechrono is a great application, and self-made sensors will be perfect if they can support IOS.

aol

Yeah... iOS is not yet supported by the RaceChrono's DIY stuff. Only because Bluetooth RFCOMM is not open in iOS. Need to create equivalent API through Bluetooth LE which is open in iOS.

lzzl551

@AOL Do you have a timetable for BTLE support?

aol

No, I got A LOT to do before I can start on that. But maybe this thread will help me to build a test device, so I can start experimenting with it :)

DrMotor

@lzzl55: About RPM AIM, Alfano, etc use only a wire as capacitive pickup. I have not tested this, but.... http://www.sportdevices.com/rpm_readings/index.htm

Another idea: Use a Hall element with a permanent magnet behind towards the starter gear teeth (a new application for my pedal sensor :-) 70 teeth at 12 000 rpm would give 14 kHz signal. Google says Arduino can measure up to 50 kHz -- so this should be possible.

DrMotor

Link to sketch of RPM sensor at starter gear: The arrow indicates sensing direction of Hall chip. https://drive.google.com/file/d/1-aPG927oz2Yothz3cHr2BcT3w20tTJCj/view?usp=sharing

This layout should give nice symmetric magnetic flux variation through the chip. It is of course possible to arrange it other ways.

ChesLans

Hi...i am a new user here. As per my knowledge there are only three companies in the world that produce kart data recording equipment. AIM, alfano, unipro and AIM are monopolized. So the price is very expensive. My current idea is to replace mychron5 with mobile phones. I want to record GPS, RPM water temperature three data.

DrMotor

Mychron5 is better for serious racers -- much easier than DIY. However: the following combination of parts cost < $30 on Aliexpress and work with RaceChrono and phone: -- Control board: Blue Pill (Arduino) STM32F103C8T6 -- Programmer: ST Link V2 (needed if your Blue Pill does not have Arduino bootloader) -- Bluetooth module: HC06 -- DC/DC 12V to 3.3V (from 12V start/ignition battery) -- GPS: EYEWINK-VK2635U7G5LF 10HZ -- Volvo 240 water temp sensor (M10x1 2kOhm thermistor, fits Rotax Max)

My kart has single speed transmission so the Arduino program can calculate RPM from GPS $VTG signal. Drawback: I need to update the program after changing sprockets or wheels.

BTW: Can RaceChrono calculate and display "shaft RPM" based on rolling distance per rev? Would be easier to change a value in RaceChrono/phone than in Arduino prog.