I thought electric cars where supposed to sound like Starships?

So, we are here again.  As usual, I have to tinker.
Now the plan is ANYTHING that gets added to this car will be non-intrusive.  That means I am not going to snip into any of the factory  wiring or anything.
This stuff is for me, and not for sale.

First on my list was to make a PCB for the sound effects system.   I based the design on a Teensy 3.2 (because I had an old spare one), and a Robertsonics Wav trigger module (because I had one of those as well!).

The idea is that I can set a sound effects to play from an additional speaker system that I will add to the space under bonnet.
Totally independent from the cars (lacklustre) sound system.

I need to deduce speed, acceleration and deceleration.  I also need to have some way of setting the sound effects, sensitivity etc.
So, I decided to use my phone for that purpose. It's always in the car anyway.

So, the basic system will be as follows:

1. Teensy 3.2 processor
2. Robertsonics Wav trigger board.  Used to store the engine sound effects, as this board has 1 octave pitch shifting.
3. HC-06 Bluetooth module.  Gives me comms to my Samsung S22+ phone.
4. JQ8400 MP3 module + USB stick.  Gives me independant access to MP3 files for instant sound effects that are not influenced by the shifted pitch of the engine SFX.
5. Pam8403 Onboard amplifer.  Not really needed, but I have some PCB's pre-made here so why not.
6. MPU6050 Gyro module for acceleration data.

The phone will provide all the settings to the system via a custom app I wrote in MIT App inventor 2.
It also transmits the GPS data of how fast the phone is moving. This will give me a the variable speed data.

MIT APP Inventor 2

MIT APP Inventor 2

MIT APP Inventor 2

The PCB came out quite nice.  Everything seems to fit where it need to.
Added a couple of Buck DC converters to give me some clean 5v supplies.  One runs the HC06 (These modules are electrically noisy), and the other runs all the other parts.

The pre-amp audio output is via a couple of screw terminals or a 3.5mm stereo jack.  I am using the jack, as I can then fire the signal through a ground loop isolator first (space on the right of the board for that).

This board was designed to fit in a black ABS box in the engine bay (well, the front where the engine should be).

My PCB for the sound system

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Lets prototype.

So I breadboarded all the components to make sure the base circuit would work.
When I was happy that it was viable, I had the PCB made.

There are small 3d printed 'supports' underneath the JQ8400 MP module, the HC-06 Bluetooth module, the MPU6050 gyro and the USB stick.

Not sure I will leave the Pam8403 amplifier onboard yet.
It's handy for testing, but probably not needed in the final install.
It does however, simply unplug.

Breadboarded and being tested

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The biggest job BY FAR was actually finding and editing all the sound effects.
I scoured the internet for royalty free spaceship engine sounds, weapons and anything that sounded cool.
I also wanted Kylo Ren's Tie-fighter engine noise.  Ended up having to make that with my sound editor.

There are 50 WAV engine sounds, and 90 start, stop and weapons SFX.

Once I had all the files. the WAV files for the engine were loaded and sorted onto a MicroSD for the WavTrigger board.
The start and stop SFX, plus all the weapon noises were converted to MP3 and stored on a 1GB USB stick for the JQ8400 MP3 module.

All these file storage mediums were run through Drivesort.exe to make sure they were stored in the correct file name order.

Work in progress!