Volume Knob for 2020 Pioneer DMH NEX Car Radios (and Others Too)
Introduction: Volume Knob for 2020 Pioneer DMH NEX Car Radios (and Others Too)
If you have any radio in the Pioneer DMH NEX series that came out in 2020 (DMH-WT8600NEX DMH-WT7600NEX DMH-WC6600NEX DMH-W4660NEX and DMH-W4600NEX) you probably noticed they don't come with a volume knob. This is annoying because if you don't have steering wheel volume controls, you have to take your eyes off the road to find the area on the screen to touch to adjust the volume.
But never fear, there is an answer. You can make a volume knob without knowing much about electronics by using cheap generic parts from ebay and amazon. This knob uses a chip on a small circuit board called an "arduino", a longtime favorite for hobbyists and beginners as well as experts.
I had no experience with electronics before this project. The most I had done is install the radio, which I was forced to do myself because the pandemic had shut down the installation services in my area. But this project was a great (and satisfying!) introduction to the hobby.
We aren't modifying the radio, just plugging a cable into the W/R port. It doesn't involve risk of electric shock because these are low voltage components powered by USB. The knob is powered through a USB port somewhere in your car. You can power, though not charge, multiple devices like dash cams with a single USB port using a USB splitter or hub. And if you installed your radio, you know that car panels can be pried off and on and wiring can be safely hidden behind them.
This works on this series of Pioneer radios and could work on other brands that have an unused “W/R” port in the back, as long as you can figure out by trial and error or through the internet what the correct resistance levels are that are interpreted by that brand of radio as volume commands. You can use this same code and change the resistance levels in the section of code identified in step 3.
I’d like to thank the redditor <PERSON> for creating this project first and for helping me do everything you see here. He wrote the arduino code and to him is owed all the credit for coming up with this.
Supplies
What you'll need is:
1. A soldering iron and solder (I recommend rosin core solder). If you've never soldered before, watch a youtube video on how to strip and solder wires, and solder pins on electronics components. Here's what I watched: https://www.youtube.com/watch?v=oqV2xU1fee8
2. A multimeter.
3. A breadboard. This is a rectangular piece of plastic with a bunch of holes you can stick wires into. It has metal rails inside that make connections between wires you stick into it. 485
It will allow you to test out all the electric connections and make sure your knob works before soldering it all together. This is what they call "prototyping."
4. Search breadboard wires on amazon. Get a set of male to male, female to male, and female to female wires. You can use these for prototyping and if you don't want buy additional 22 gauge solid wires for the final product, you could also just use these in the final version of the knob you make. Just make sure to actually solder them because if you just connect them they might come disconnected from wear and tear.
5. A rotary encoder. This is the stem for the knob that senses when you’ve turned it or pressed it. Pressing it will send a track forward command, which I like to use to skip through podcast ads, as it goes ahead 15 seconds in CarPlay. I used the most common cheap version which can be found by searching "rotary encoder for arduino." You can get a nice brass or aluminum knob for it on ebay with the standard 5mm diameter fit if you don't like the plastic one the encoders come with. I recommend "knurled" guitar knobs for that nice finger feel.
6. A 3.5mm male stereo cable. Make sure it has 2 black rings, not one ring which would be mono. You can salvage one from an old set of headphones. This will be the connection to your stereo. It plugs into the "W/R" port, which is how steering wheel controls used to connect to radios in the old days. Not sure why they still have that port on a 2020 radio, but this is lucky for us.
7. An Arduino Nano microcontroller. There are many generic clones of these little things that should cost no more than $3-5 a pop. 98