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Topic: Powerboat racing telemetry. First steps taken, many to go. Support appreciated. (Read 6249 times) previous topic - next topic


Remarkable how difficult simple things can get. I'm trying to translate the product I need to something that shops use to describe it :)

If found two things:

Turning knob with a lot of pins, a pin selector. This plus a bucket of resistors and I can make every selection give a different voltage. Thus letting one Arduino pin listen to that and decide what variable to use.
Put that into one housing and it's called a.... detented potentiometer.  (correct?)
Or perhaps better said: take a potentiometer, add a bunch of notches to the axis/knob and it will have a certain resistance at every position. Where the detent are the notches that you feel when you turn. and it should have those positions numbered around the knob.
Bloody simple, used in handsfull in every cockpit but I just haven't found a low-cost, simple product from a shop that will not take weeks to get it to me.

I'll call some shops in the region to get the Dutch name for it. And perhaps even the whole item.

The idea is to have four selectors that each use one pin on the Arduino.

However.. I found something called 'digital potentiometer'   Could that be a way to connect them all to ONE pin? Sounds like lots of code to decipher the digital signal but perhaps I'm wrong with that fear?

@PeterH  thanks for the information. I've found a company (link) that you probably mean. Adding up a few items brings me to 1000 pounds in a second.  That's way too much for our current situation. Also, it would take out a lot of tinkering and thinking for the team to learn from why, what and how of telemetry and using it to go faster. Pay, plug and play is not quite the aim of this game.

@WildBill:  yes, that is a good idea. Perhaps it's possible to create a small circle the GPS can move in without triggering the logging. Perhaps add input from the gyro or engine start. The boat is lifted out of the water after almost every run. The engine is started at the beginning of every run. But also shut down before the actual race runs. So perhaps engine start, starts the logging. Engine stop does not stop it immediately.
A switch in the cockpit would be possible but a possible source of error: stressfull times at the start so forgetting to flip it is easy.


I think you are referring to a stepped attenuator, which is a switchable resistor ladder, often used in high-end audio systems.



Dutch word is "draai schakelaar 1/12"
Conrad.nl search on it! 3 Euro and on stock.
Use one of the analog ports for these selectors. With 10 differrent resistors you make a ladder and each step will give a analog value.
There are even resistor ladders ready to go.
With the skech you determen which step of the analog selector step is which setting 1 to 10.

If I can assist let me know by PM in Dutch.

Also make an update list which ports and functions of the UNO you currently use.

A switch in the cockpit would be possible but a possible source of error: stressfull times at the start so forgetting to flip it is easy.

Make an optical beam sensor. No driver is no data recording. In case the boat flips and he is thrown out then data recording also stops that is a downside of it. :-)

Never to old to learn and I learn every day


I have done some more thinking on this project.

For the 5 or more fixed values.
Use an I2C 4 x20 display with 5 pushbuttons (joystick).
This will take 3 analog ports (if you have them left over)
Display and button at the rear of the boat where the engineer does his adjustments.
When finished it, is his duty to set the correct settings with the buttons and display.
As soon as recording is started by the driver going into his seat this data is recorded too.
Display info:
prop 09        fuelmix 10
tilt 07          optional 00
camber 03    optional 00
caster 01     optional 00

Does the engine has and ECU output?
In that case engine data could be stored by OBD to the SD card too like RPM.
I would not mind start and stop for fixed data.
Just record all of it with a 20 ms timestamp, it are all just bits and bytes and to fill up 32 Gb with a refreshrate of 20 ms would be no problem to record a race if I am not mistaken.
After the race like you said work over the data in excel or an other purposed written program.

Never to old to learn and I learn every day


Thanks for the thinking and sharing.

The 12 position switch plus bunch of resistors (or stepped array, even better) is indeed the functionality that I am considering as the best solution. I understand that this may be used in electric guitars.

For the prototype we can probably get acceptable results with simple potmeters with a button that has an arrow plus a dial with some numbers. Set them to the value needed, push a button for the intterrupt and changes untill the next push on the button are not used anyway. Check and set each pot after every change is a simple procedure. As long as the button does not cause an interrupt by itself it should be allright. In the actual situation, all settings can be visually checked quickly anyway. There are no changes made that are hidden under covers of the hull.

Thanks for the name dwx00d, I'll continue my search with those terms. Bit big first find :D :)  even diy kits (wow  :smiley-eek:

here's a smarter solution using a pcb:

bottom of the page, so audio business is where they are

The engine does have some ECU output but we don't know much about it. It is not sure yet if it is standard (somewhat) OBD or something proprietary. The small display that comes with it shows various data and steps through them, don't know yet what is done to decipher the incoming data to those values. Will take some time and equipment to figure that out.

Start/stop is indeed no big issue, but it may be usefull to avoid filling a datafile with loads and loads of almost identical data (GPS always changes somewhat). Instead of having to chop it up later.

I like the idea of a display and such. I also know the mechanics though...... :)  analog, arrows, button = their world ;)   displays, cursor, push up/down = ouch!

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