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Comment by dcz_self | Hacker News Reader

I'm still going at my bike computer - you know, the open source, hackable one.

I spent the past 2 months improving Tock OS - added GPS and file system - and yesterday got the display running:

https://github.com/tock/tock/issues/2846#issuecomment-108617...

I could use some help adding new drivers (esp. Bluetooth, but also simple ones like touch screen) and if someone explained Bluetooth Low Energy or Apache NimBLE to me, that would be awesome.

Contact me here or through the web page (which needs some work too): https://jazda.org/community/

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I'm not sure I 100% follow. It says "bike computer" do you mean a literal computer attached to the bicycle? I saw the github it shows some software runing on PineTime.

Edit: actually I guess that is not the PineTime in the photo, knob is on the right side.

A bike computer is the name for a device you put on your bike to show you useful info like speed etc.

Typically they are about as flexible as calculators, but this CPU has been shown to run Doom, so it's a general-purpose computer too :)

https://github.com/next-hack/nRF52840Doom

Whoa that's pretty neat. Do you have a physical prototype yet like a 3D printed case around it, battery, etc? I know you mentioned GPS but wondering if you would consider a hardware input like an rpm reader on the tires.

Yes, I have ordered a batch of smart watches that go on the handlebars, same as the prototype on the photo.

I will sell them together with a Bluetooth wheel/cadence sensor once I figure out Bluetooth.

That sounds pretty cool. Good luck.

I'd be curious on design choices like waterproofing, battery life, things like that. Also I think you mentioned your site is getting worked on but pictures to clarify what it is about would help sell it.

The watch hardware is waterproof (but not submergeable), it works for 1 day without special optimizations (all-disabled-low-power-mode on original firmware about 2 months), it has a sunlight-readable display which should work with GPS for at least 6 hours without any optimizations. That's enough for a trip. It only has 8MiB storage space, but that should cover a couple hours worth of GPS track. It's the same device as used by Bangle.js 2.

The web site was put up before I started the firmware work, so obviously no pictures :) They will come once the project becomes more useful.

Doom on the 52840 is impressive!

I don't know if this is something I'd want to build, but I spent 5 years at an outfit that designed/built a variety of fitness devices like this, including some of the consoles on gym equipment you may have used.

You mentioned 'figuring out Bluetooth (BLE, please)" in another post. What are you having trouble with? The sample code in the Nordic SDK is pretty good in most cases.

The Nordic SDK is out of the question. It's not Free Software, and there's already plenty of non-free-software devices out there.

I will have to port the NimBLE stack to Tock OS, and that's guaranteed going to be complicated, so someone who knows at least how Bluetooth works in general would be invaluable.

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