Bootloop at Car Startup Sometimes

[Bo3lwa]

Hello everyone,

So I've got the head unit connected and everything and it works great. However, about 70% of the time, the device keeps starting then turning off just after starting the car. I could get it to boot properly by disconnecting and reconnecting the 5V input from the pi itself, this works every time, but it's annoying. Did anyone else have this problem?

I suspect that when starting the car, the voltage from the battery would drop for about a second due to taking so much power to start the engine, this could drop the voltage so low for the 5V converter that it would not supply enough power for the pi, the pi would recognize this and would keep restarting until the power is disconnected then reconnected. I think it also doesn't help that I've configured it to enable the turbo for the cpu on startup (I don't remember exactly but it might be something like 2.5GHz for the startup).

I'm thinking of getting a super cap or something to supply the pi with enough initial power but I don't want to go through all that trouble if there is a better solution, or even if the initial power isn't the problem.

Thanks in advance!

[Daniel_BlueWave]

I would also go into direction of voltage drop. RPi is very sensitive for voltage drops.
You can checks others Users solutions from here:
https://bluewavestudio.io/community/forum-91.html

[KreAch3R]

I've had my share of bootloops at start and it came out that it was a combination of a normal voltage drop during crank (small one), and the biggest factor, the pi peripherals were drawing too much power during startup.

Disconnect everything non essential and check if it still happens.

Also, some cars cut out power to audio systems (where have you connected your 5V converter??), and that can cause a momentary drop in voltage so pi thinks it was a restart cycle and can get stuck restarting. Use a relay mechanism to draw power directly from battery but use the switched-on current of the crank to toggle the relay.

Re-check all your connections and solders (if any), and thicken any clumpsy looking connection hanging by a thread. That could solve some voltage drops.

Lastly, buy a external 12V or 5V powered usb hub, and connect all peripherals to that, and that to pi.

All of the above solved the problem for me. I never get bootloops at startup these days.

[Bo3lwa]

I've had my share of bootloops at start and it came out that it was a combination of a normal voltage drop during crank (small one), and the biggest factor, the pi peripherals were drawing too much power during startup.

Disconnect everything non essential and check if it still happens.

Also, some cars cut out power to audio systems (where have you connected your 5V converter??), and that can cause a momentary drop in voltage so pi thinks it was a restart cycle and can get stuck restarting. Use a relay mechanism to draw power directly from battery but use the switched-on current of the crank to toggle the relay.

Re-check all your connections and solders (if any), and thicken any clumpsy looking connection hanging by a thread. That could solve some voltage drops.

Lastly, buy a external 12V or 5V powered usb hub, and connect all peripherals to that, and that to pi.

All of the above solved the problem for me. I never get bootloops at startup these days.

Alright that's a lot of good info. I think I'll try to delay the powering of USB devices using the
 

USB_MSD_PWR_OFF_TIMEUSB_MSD_PWR_OFF_TIME

Parameter in the boot file. It can be set for the Pi3, hopefully it also works in the Pi4. If not, I'll delay powering the Pi in my power circuit for something like 2-3 seconds. If that doesn't work, I'll try the external USB power.

To answer the question about the converter, it's connected directly to the battery, but the pi ground is connected to a MOSFET that's controlled by an ESP32 so I can freely control when it powers on.

---

I would also go into direction of voltage drop. RPi is very sensitive for voltage drops.
You can checks others Users solutions from here:
https://bluewavestudio.io/community/forum-91.html

Hopefully, a delay in powering the pi after The crank helps with avoiding the voltage drop.