Arduino Translates Signals Between Steering Wheel Buttons and Aftermarket Head Unit

DIY Steering Wheel Control Adapter

There is no question that steering wheel mounted controls are super convenient. Reaching all the way over to the dashboard to change a radio station is so 1990’s. An ever-increasing percentage of new cars are coming equipped with steering wheel controls for the stereo, however, you’ll lose the button control if you change out the stock head unit to something a little higher in quality. Sure, there may be an adapter readily available for your car/stereo combination, but there also may not be. [Ronnied] took the DIY road and made his own adapter.

The first obstacle for [Ronnied] was to figure out the wiring on the steering wheel controls. After some poking around he found that there were only two wires used for all of the control buttons, each button only changing the resistance between the two wires. The button states could easily be read by using an Arduino’s analog input. A Pro Mini model was chosen for its small size as it could be housed in the radio compartment of the dash.

The next step was getting the Arduino to control the aftermarket head unit. [Ronnied] did some research regarding JVC’s Stalk digital control interface but came to the conclusion that it would be easier to direct wiring the Arduino outputs to the appropriate spot on the head unit’s circuit board. To do this the button for each function that would also be represented on the steering wheel was traced out to find a common point on the circuit board. Jumper wires soldered to the circuit board simply allow the Arduino to emulate button pushes. To ensure that the head unit buttons still work in conjunction with the steering wheel buttons, the Arduino would have to keep the pins as inputs until a steering wheel button was pushed, the pin changed to an output, the signal sent and the pin changed back to an input. This feature was easily created in the Arduino sketch.

Video below.

[Read more...]

Repairing a VFD driver on a car stereo

We love seeing repairs and always marvel at the ability to track down the problem. [Todd] seems to have a knack for this. He was met with a lot of adversity when trying to get the Vacuum Fluorescent Display working on his car stereo. A lot of persistence, and a little bit of taking the easier way out let him accomplish his goal.

The head unit is out of his 1994 Jeep. He knew the radio functionality still worked, but the display was completely dark. After getting it out of the dashboard he connected it to a bench supply and started probing around. He established that the data lines were still working by setting the radio to auto scan mode and testing with a multimeter. When he went to measure the cathode pins he didn’t get any reading. It seems the driver which supplies that signal is burnt out.

One easy fix would be to replace the parts from a scavenged unit. [Todd] hit the junkyard and picked up one from a Jeep that was just one model year apart from his. Alas, they weren’t exactly the same, and although he swapped out a chip (using a neat heated solder sucker) it didn’t work. In the end he simply dropped in a power resistor to use the 12V rail as a 1V at 0.1A source for the filament.

You can see his repair extravaganza in the video after the break. If you’re looking for tips on scavenging these types of displays check out this post.

[Read more...]

Galaxy SIII hack puts Android in your dashboard

Here’s how you can have a hands-free, no worries about the battery, Android experience while you drive. [Steve] removed the head unit from his car and replaced it with a Samsung Galaxy SIII Android phone. The look is pretty nice, but we do have a few suggested improvements if you try this one for yourself.

It started simply by removing the factory stereo which left a double-height opening in the dashboard. [Steve] cut a piece of wood to fit the gaping hole, painting it a grey that would compliment the interior colors of the car. The phone is mounted on this plate, with plenty of room for the USB and audio cables. From there it is finished up with another wooden plate which has a cutout for the touch screen. See the final project, as well as glimpses of the installation, in the video after the break.

[Steve] demonstrates using the GPS features and playing music. We’d improve this in a couple of ways. First off, using something like the IOIO board you could add a physical volume knob, which we’re not interested in giving up for a touch screen quite yet. If you were willing to go the extra mile, a CAN-BUS chip could be added too that would monitor button presses from the steering wheel music controls.

[Read more...]

Turn your old Bluetooth headphones into a DIY car audio receiver

wireless-car-audio

[Tim] drives a 1995 Mitsubishi TS Magna, which is equipped with a less than stellar accessory package he lovingly calls a “poverty pack”. He outfitted his ride with an aftermarket head unit that can support the Bluetooth A2DP profile, provided he buys the ridiculously overpriced kit sold by Pioneer. Reluctant to shell out more money on an audio kit than his car is worth, he whipped up his own Bluetooth kit for far less than Pioneer’s asking price.

He had a set of Nokia Bluetooth headphones that he was willing to part with, so he disassembled them to see how he might interface with his car stereo. Connecting the headset to his head unit was a relatively easy task, but he had to work a bit harder to get his Bluetooth receiver powered properly.

After both undervolting and then nearly cooking his wireless audio rig, [Tim] managed to get things operating to his liking. He says that the audio is a touch quieter than he would like at the moment, so he will likely be revising his design in the near future. For now however, he can stream tunes from his phone while he cruises around town.

Building a custom interface for surplus HF radios

[PRC148] picked up a Motorola Micom radio from eBay. These are US State Department surplus, but apparently the 125 Watt HF units are top-of-the-line at a tenth of the sticker price. The one hangup is that they’re headless; you can’t control them without additional hardware. But the Internets are often kind to the hobbyists, and this is no exception. You can get software to run the radio from a PC thanks to the Micom Yahoo Group. [PRC148] took that software as an example and built his own stand-alone interface. [Cached version of the page]

The head unit is an Arduino driving a four-line LCD display and a rather large array of buttons. The forum thread linked above shows his humble beginnings on a breadboard. During the project [PRC148] learned a lot of skills to end up with what you see above. Hiding behind the reused bezel is a PCB he designed in Eagle CAD and etched himself. It allowed him to cram the tactile switches close enough to work with the button overlay on this keypad.

UPDATE: The traffic from this feature took down the forum hosting the content. They requested that we do not link to them because of this. A cached version without images can be found above thanks to [Termm].

Dash-mounted Nook Color is a perfect head unit replacement

jeep-nook-mount

XDA forum member [craigbru] wanted to beef up the audio setup in his Jeep, and thought that his Nook Color would make a suitable replacement. Since he jailbroke the e-reader, the head unit upgrade lets him do just about anything you can imagine, all from the comfort of the driver’s seat.

Seeing that he would continue to go off-road with the Jeep, he wanted to construct a mounting solution that was convenient and sturdy – something we think he did very well.

The dock was constructed using a Quadratec iVault stereo mount, along with a plastic tablet mount he had on hand. Because convenience was a primary goal, he put together a quick release charging solution as well as a simple audio interface using a set of touch contacts. This allows him to connect and detach the tablet from the Jeep without having to fuss with a bunch of cables each time. He also added an audio equalizer along with a Bluetooth OBDII interface to the setup, allowing him to tweak his tunes and monitor his engine with ease.

We think it’s a great-looking setup, and we’d be lying if we said we didn’t want one as well.

[Thanks, MS3FGX]

The Rube-Goldberg of car audio

[Anthony Pray] had his car stereo stolen. When thinking about replacing it he realized the he and his wife never used it for anything other than an Auxiliary connection to play songs from their cellphones. So instead of buying a head unit he pulled an unused home audio amplifier out of a dark corner of his house and wired it to the car speakers. Problem solved, except that the under-dash installation meant the only volume control is on the phone playing the audio. He decided to build a wireless audio controller that would let him send commands to the phone without quite as much distraction from the road.

The device you see above is his creation. What a beauty. But seriously, it’s so random and hacked together how can you not love it? And, it works!

The frame is made from plastic coat hangers, and the wheel is an old RC control knob. There’s even a play/pause feature built from the clicking properties of a retractable ball-point pen. A Cypress PSoC board reads the knob and pen positions, then pushes commands via a Bluetooth module in order to control the phone. He recorded a testing video (after the break) which gives you a better look at the functionality of this setup. [Read more...]

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