When I started preparing CaRadio for installation in my Volkswagen Golf, the first thing I decided to try was reusing the original RCD510 head unit.
I had already done something similar with a Mystery head unit in my Volkswagen T4. Back then, an existing head unit became the foundation for my own device, so repeating that approach seemed logical.
Besides, the RCD510 already fitted perfectly into the Golf's dashboard. I just needed to figure out which parts of its electronics I could keep and which would have to be replaced.
Inside the RCD510
After taking it apart, I quickly realized that the RCD510 was considerably more complicated than the head unit I had worked with before.
This wasn't just an amplifier board with a few buttons. The main electronics, display, and head unit controls were closely interconnected.
My original plan was to keep the mainboard, use its amplifier and factory power management, and replace the original screen with a Waveshare display connected to the Raspberry Pi.
In theory, it all seemed perfectly reasonable. Why build my own power supply circuit and buy a separate amplifier when the necessary components were already inside the head unit?
But first, I had to figure out how to turn everything on.
Early Success on the Workbench
Eventually, I managed to find the points on the board responsible for controlling the power.
This was important because I wanted to preserve the factory power-on behavior. The car sends a command over the CAN bus, the RCD510 wakes up, and the Raspberry Pi receives power along with it.
The first tests took place on my workbench.
I had to turn the head unit on manually and enter its PIN code. After that, it continued working even when I disconnected the original display board.
At one point, the setup looked almost ready. The Raspberry Pi booted, the power control signals I had found worked as expected, and the original head unit electronics continued doing their job.
It seemed that all I had left to do was install everything in the car.
Things Were Different in the Car
But once I installed the setup in the Golf, the problems began.
In the car, the RCD510 was unlocked through the CAN bus, without manually entering the PIN code. And it was in this mode that I discovered the main electronics would no longer work properly without the original display board.
The head unit entered a continuous reboot loop.
Even worse, the power control points I had found started behaving unpredictably. On the workbench, they had worked exactly as expected. In the car, the signals kept switching on and off, causing the power to appear and disappear repeatedly.
As a result, the Raspberry Pi could begin booting, but I couldn't get the entire setup to work reliably.
I never figured out why the RCD510 behaved so differently on the workbench and in the car. Perhaps it had something to do with the startup sequence or the mainboard's dependence on the display electronics.
I would have liked to investigate further, but I was running out of time.
When Reliability Matters More Than Experimenting
I had a long road trip coming up, and I needed working navigation.
Of course, I could have continued investigating the RCD510, searching for the cause of the reboot loops and trying to work around the limitations of the original electronics.
But another question came up: how safe was it to leave a setup like this installed in the car?
If CaRadio froze or stopped playing music, that would be annoying, but not critical. On the other hand, if faulty power management prevented the electronics from going to sleep after turning off the car and drained the battery while it was parked, the consequences would be very different.
So I decided to stop using the original RCD510 mainboard.
Instead, I bought a ready-made amplifier module. This meant I would have to handle power management and the other functions myself, but at least I would no longer depend on the unpredictable behavior of the factory electronics.
Not Quite the Result I Had Planned
Originally, I wanted to keep as many of the RCD510 components as possible and simply add a Raspberry Pi with CarPlay.
In the end, almost the opposite happened. The factory electronics turned out to be too complicated for a quick modification, so I had to move toward a completely custom setup.
Now I needed to put everything together, solve the Raspberry Pi power management problem, and get the system working properly in the car.
And that involved a few compromises of its own.
But that's a story for the next article.