robbrad
Posts: 3
Joined: Sat Jul 05, 2014 7:50 am

Reverse Engineer V-fit Tornado Air Rower

Mon Jan 15, 2018 4:50 pm

Hi All

This kind of thing has been done before but before I go hacking my new rower to bits I am wondering If I can do something a little less intrusive and use the existing wires and sensors in my Cheap and cheerful V-fit Tornado Air Rower to pick up readings for the Raspberry Pi. I couldn't afford a Concept2 :cry: - so settled for this rower instead.

Eventually Id like to program it to connect to a TV on the Wall that can form some meaningful stats or even some semi-competitive AI turning it into a game.

The way the rower works currently is there are two sensors (both from what I can see magnet and sensor, I believe this is hall effect) - the flywheel has 2 magnets and the seat has one. Seat measures the stroke and the flywheel the speed.

Photos

Existing Monitor PCB
Image

Existing Connections to Sensors via 3.5mm JACK ??
Image

3.5 mm jack showing the two wire interface
Image

Seat Magnet
Image

Seat run bar sensor
Image

Flywheel Sensor
Image

Inside flywheel - little hard to see but shows two magnets
Image


My questions
1. Can I make use of existing sensors to the RPi?
2. The sensors have two wires - I guess a positive and negative - most Hall sensors are three?
3. Which GIPO pins on the RPI should I connect to to get this to read
4. is there any other electronics I need to get this working - ultimatly the best thing would be a 3.5 mm female for both which would mean I could detach the Rpi when ever I wanted
5. Anything I need to be aware of here?

pcmanbob
Posts: 6438
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Reverse Engineer V-fit Tornado Air Rower

Mon Jan 15, 2018 7:45 pm

Before you can decide if or how to use these sensors you need to figure out what sort of sensor they are.

First you could just connect a digital meter set to ohms across the output of each sensor to see if they are just reed switches.

You could also take a closer look at the circuit board they feed in to and see if you can workout which part of the circuit they are connected to, this may lead you to identifying a chip that takes the input, you can then look up that chip and you might then be able to decide what sort of out you get from the sensors.

Once you know what sort of output you get from the sensors you can then decide how to connect them to you I gpio.
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robbrad
Posts: 3
Joined: Sat Jul 05, 2014 7:50 am

Re: Reverse Engineer V-fit Tornado Air Rower

Mon Jan 15, 2018 11:27 pm

I have done a bit more investigation.

In parallel to the seat sensor is a capacitor - but not for the flywheel sensor (I guess this must be to reduce double readings when the seat passes back over the sensor)

When I set the DMM to Diode I get two different readings - when the magnet passes over the switch / sensor it goes to zero.

Seat = 0.776
FlyWheel = 1.611

For Ohms at 20M
Seat = 3.76
FlyWheel 3.76

Also there are no chips as such there are just these little displays which seam to have bar connectors on the back of them.

Photo of PCB
Image

User avatar
piglet
Posts: 900
Joined: Sat Aug 27, 2011 1:16 pm

Re: Reverse Engineer V-fit Tornado Air Rower

Mon Jan 15, 2018 11:31 pm

The chip is under the chocolate button. I don't think knowing more about it would help you.

pcmanbob
Posts: 6438
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Reverse Engineer V-fit Tornado Air Rower

Tue Jan 16, 2018 10:38 am

Well if the switches go from a resistance to zero when the magnet passes over them I suspect the are just reed switches so you could connect them to the pi gpio like any other switch.

examples.
https://github.com/raspberrypilearning/ ... up_down.md
https://projects.raspberrypi.org/en/pro ... omputing/7
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