Posts tagged "electronics"

Using your car as a giant joystick for $20

Mon 18 December 2017

DISCLAIMER: Cars can be dangerous. The electrical and mechanical systems of a car are not designed for this use case, and you run the risk of damaging them. This project worked fine for this particular vehicle, but could damage critical systems such as steering and braking in a different model. Do not attempt this with a vehicle that isn't yours, or a vehicle that would leave you with no contingency if it were to break. The author will not be held accountable for any damage caused from following these instructions.

This project is about how to rig the controls of nearly any recent car (in my case a 2007 edition Mazda 3) to act as a giant game controller. In a nutshell; input from the car will be scraped as CANbus messages from a cheap OBD-II adapter, then converted to standard joystick and keyboard events, which will be used to drive a video game projected onto a screen in front of the windshield. No physical modifications to the car are required; the only one I made was to pull the fuses for the headlights so as not to blind the projector screen.

The full source code used for the above demo is available at GitHub. With luck, anyone with entry-level Python experience should be able to adapt this for their car. I think this is a nice practical introduction to car hacking and reverse engineering, without the need to spend a lot on exotic debugging hardware.

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Dead KORG microKEY, Part 2: Noobface McHamfists Desolders His First SMD

Fri 17 June 2016

Oh God. Oh God. I've been putting this one off, but the stuff has arrived. I can't back down now!

A brief résumé of what happened in Part 1: this great little KORG microKEY MIDI controller stopped powering up for reasons unknown. By wiring it up to a J-Link debug probe, we found that the CPU was still alive and kicking, yet somehow the computer was receiving garbled USB messages. As this keyboard has a built-in USB hub, the stab-in-the-dark diagnosis was that the chip responsible (a Genesys GL850G) had gone bad and needed replacing. Unfortunately, the chip is a 28-pin 10mm*8mm surface mounted design, and our bumbling hero has never before soldered an SMD component, much less reworked a board!

To properly capture the fear of someone doing surface-mount rework for the first time, everything in this piece was written minutes after happening.

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J-Link Detective Squad: Dead KORG microKEY-37

Sun 08 November 2015

I love the KORG microKEY 37. It's an excellent entry-level MIDI controller that fits unobtrusively on your desk, great for impromptu jamming when you should be focused on something boring like "tax" or "finding a new house before eviction day". The keys feel pretty soft, as they use rubber domes instead of metal springs, but the velocity response is excellent. I highly recommend it, as it's one of those products which basically lives forever and delivers year after year of good service.

I bring this up because back in about February, my KORG microKEY 37 stopped turning on. The unit would no longer connect via USB; each time it would give up at different points during the initial handshake, with dmesg spewing a number of unhappy messages. Here's one attempt at plugging the device in.

[Sun Sep 27 06:00:56 2015] usb 3-1: new full-speed USB device number 17 using xhci_hcd
[Sun Sep 27 06:00:56 2015] usb 3-1: device descriptor read/64, error -71
[Sun Sep 27 06:00:57 2015] xhci_hcd 0000:00:14.0: Setup ERROR: setup context command for slot 16.
[Sun Sep 27 06:00:57 2015] usb 3-1: hub failed to enable device, error -22
[Sun Sep 27 06:00:57 2015] usb 3-1: new full-speed USB device number 18 using xhci_hcd
[Sun Sep 27 06:00:57 2015] usb 3-1: device descriptor read/64, error -71
[Sun Sep 27 06:00:57 2015] xhci_hcd 0000:00:14.0: Setup ERROR: setup context command for slot 17.
[Sun Sep 27 06:00:57 2015] usb 3-1: hub failed to enable device, error -22
[Sun Sep 27 06:00:57 2015] usb 3-1: new high-speed USB device number 19 using xhci_hcd
[Sun Sep 27 06:00:57 2015] usb 3-1: Device not responding to setup address.
[Sun Sep 27 06:00:57 2015] usb 3-1: Device not responding to setup address.
[Sun Sep 27 06:00:58 2015] usb 3-1: device not accepting address 19, error -71
[Sun Sep 27 06:00:58 2015] usb 3-1: new full-speed USB device number 20 using xhci_hcd
[Sun Sep 27 06:00:58 2015] usb 3-1: Device not responding to setup address.
[Sun Sep 27 06:00:58 2015] usb 3-1: Device not responding to setup address.
[Sun Sep 27 06:00:58 2015] usb 3-1: device not accepting address 20, error -71
[Sun Sep 27 06:00:58 2015] usb usb3-port1: unable to enumerate USB device

Oh snap! I'm torn on what to do... buying a replacement is doable, but this one was limited edition and a replacement wouldn't be the same cool colour scheme! Maybe there's a clue to what went wrong inside the unit?

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