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Introducing Project eChook Nano
edited June 2017
Need a bit more help.
I've done the arithmetic for roadspeed, confirmed the wheel rpm etc and my maths gives me a different answer to what is being displayed - it's under-reading by abou 9 mph. Have checked the magnet count - correct, have checked the wheel circumference - correct. Any pointers ??
The logged speed is in meters per second and the app has the option of displaying speed in a few different units... That would be the first thing I'd check.
Second thing I'd check is the orientation of the magnets... Very easy to get one wrong! Move each magnet back and forth in front of the sensor at a time and check each give a reading in the app.
If it's neither of those... I'll have another think!
So, does the orientation of the magnets poles matter as long as they are all the same?
The hall effect sensor will only pick up from one pole, so yes. It normally takes me a little trial and error to get all the magnets in the right orientation...
We've finally got our (hopefully) final prototype boards together!
These boards have a different layout, different DC-DC Voltage regulator with short circuit protection and reverse polarity protection, a lower component count and design changes to make them easier to solder. We have also differentiated the power connector to all the rest so that it is far harder to accidentally fry the Arduino! The functionality remains the same as the original prototype boards.
Thank you very much to the teams who gave us feedback on the initial boards :)
We are also re-organising and re-writing a lot of the documentation to make it easier to follow. The build instructions for the eChook board are complete, I'm currently writing up the section on connecting the board to the car and instrumenting the car.
We are providing these eChook boards in kit form, for students to build and program. All instructions are provided in the documentation. We're still selling them for £25 posted for the kit shown below. You will need to purchase the LEM HAIS 50-p current sensor(~£18) separately. This is cost price - we're not aiming to make a profit.
*Kit Photo missing a diode and length or ribbon cable that are also included.
Alternatively if you are lucky enough to have PCB making facilities, all the files are hosted at
and you can make your own :)
Not quite final prototype it seems :(
Unfortunately this batch of PCBs has had some manufacturing issues making for a very easy short to ground when soldering them up. Ian has written up a full explanation at www.wechook.com for those interested. Lesson learnt - be very generous with tolerances when ordering boards from China! That being said it's the first time we've had any issue with the board quality from this supplier.
Massive thanks to RLR Ben for alerting us to there being a problem and bearing with us while we worked out what happened!
Further orders will be delayed until we get new boards in, and any team who have ordered a kit will be sent a new PCB when we get them (or a full refund if they prefer). I've emailed all and heard back from most teams who have a kit - any questions, message/email me as always!
We have a new batch of PCBs, issue fixed. Teams who ordered the last one have already had the new boards, and we can send out new kits by the end of the week.
Since the first prototype we've answered lots of questions through email and messages, and always wanted these to be more public so they could help others with the same or similar questions - something like a forum! The lack of separate boards on this forum made it seem a little rude to encourage spamming it with little eChook questions. Now that this forum is unfortunately closing, it seems even more relevant to have somewhere to discuss all thing eChook and help each other out with anything from building the boards to analyzing that spreadsheet full of data. So for further discussions, we've set up
. It's a little empty right now but I'm sure we can start filling it up.
We will also be writing articles for Greenpowers new 'How To' section, both eChook specific, and more general ways of using an arduino with your car, so hopefully the eChook forum won't detract anything from the greenpower site.
For those interested I have now posted a build video talking through the whole build process of the new v1.2 board:
A few updates today-
Firstly we've had a few queries on how the lap counting feature works. I've updated the documentation with a more comprehensive guide and explanation, a link to that specific page (33) is here:
We have also been putting more development time into the app. A small update should be out in the next few days that adds the ability to share and clear the logged data directly from the app, and also you no longer have to type in the bluetooth device name, just pick it from a list, as well as some smaller tidying up.
We're planning some far bigger changes to improve it both behind the scenes and to the user interface... Just no promises on the timing there! Hopefully the start of next season.
We are now looking to package up the kits a bit more professionally for resale. Whether we do this ourselves or outsource it to a company, British or Chinese, is still up in the air, but if anyone here does have experience of doing something similar we'd be keen to hear from you!
Big news! The eChook app now includes telemetry :)
Ideally any telemetry option we add would be simple, secure and free. Unfortunately they don't tend to go hand in hand. Thanks to Yayra of the Driven team, we found a solution that is either simple and free, but makes any data public, or simple and secure, but has a monthly subscription (Currently 2USD per month, no contract). We have no affiliation with these sites at all, the subscription is with dweet.io and totally independent of weChook.
This isn't what we want the final telemetry offering to look like, but until we work out how to implement it, this is a good stop gap solution.
We are using a website called dweet.io to handle the data, and it can be used to display it. A more customised 'dashboard' can be built at freeboard.io. For the sake of security, location data can only be sent using the paid version - we don't want to be responsible for publicly broadcasting your location! (Lack of location also makes it harder to identify a which team a data stream is coming from... just incase anyone were to try!)
We use the phone's 3G/4G data connection to upload the data, it is then visible on any internet connected device with the correct link.
Instructions on how to set up the telemetry can be found in the documentation here:
This is what the Freeboard Dashboard could look like:
I discussed using the eChook app with a team's own built logging system at Coombe - if your logging system has USART networking (most microcontrollers and Pi's do) you can plug in a HC-05 bluetooth module and use the sendData function in our arduino code to send data to the app, and benefit from easy to set up telemetry. If anyone wants any help with that feel free to get in touch!
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