My Micro won't boot from MicroSD cards any more

[buntubaby]

Hi everyone,

My A20-OLinuXino-Micro does not boot from MicroSD cards any more.

I've tried 2 different cards (both SanDisk Ultra 16GB) and 2 Olimex images;
* A20-OLinuXino-bookworm-base-20260323-113959.img
* A20-OLinuXino-bullseye-base-20241121-172551.img
The images I wrote to the cards using Ubuntu's Disks app (restore disk image option) and when inserting the cards into my laptop they display the uboot.env file and the other folders as expected.

When powering on the Micro, the red power LED turns on, but no other sign of life.

* No power on USB ports (more precise; my wired mouse's tracking LED will not light up, my wired keyboard's capslock will not turn on; but perhaps there is power to USB),
* no ethernet port LED activity,
* no HDMI signal.

However, when I power the Micro WITHOUT a MicroSD card in it, the ethernet LEDs immediately come to life (both power and activity).

I've disconnected the Olimex SATA connector going to an SSD but that doesnt make a difference.

Any advice or things to try?

[LubOlimex]

1. Check if the voltage applied to the power jack is sufficient. The A20-OLinuXino-Micro requires between 6V and 16V DC, maybe test with 12V DC.

2. Test the SD cards. Good software for testing the SD cards is either f3 (fight flash fraud) or H2testW.

3. Try with another software to download the image to the card. I recommend using BalenaEtcher or USBImager software – they are open source source, free, have releases for Windows/macOS/Linux and using them minimizes the chances of a mistake. I've had cases where something odd was written at the start of the SD card that prevented the boot from it.

[buntubaby]

Hi LubOlimex,

Thanks for your suggestions. I tried booting the board with another power supply and it boots up just fine. So the problem was caused by a defective power supply - the SY0612E-CHINA type I bought with the board.

I tried powering the board over the USB-OTG port, but that failed. Tried three 5V power adapters (2A,2A and 1A) and two cables, but to no avail.

Is 5V and 2A not enough to power the board, a USB keyboard & mouse, HDMI and ethernet?

I will look for a quality replacement power supply in any case.

[LubOlimex]

Hello,

Glad the issue was resolved. About your questions:

- 5V adapters are not sufficient to power the board - A20-OLinuXino-MICRO requires at least 6V DC;

- A20-OLinuXino-MICRO should NOT be powered from the USB-OTG port, this is described in chapter "2.3 Powering the board" in the user's manual;

- Wattage required depends on the current drawn by the USB keyboard and the mouse, for bareboard usually 0.5A @ 12V (e.g. 6W) is sufficient but in order to be safe in your case I'd recommend at least 1A at 12V (12W)

Consider testing without keyboard and mouse inserted if the SY0612E-CHINA would work, notice that file system corruption is possible if you disconnected the power supply suddenly (e.g. without performing a software shut down). So it can be a problem with the SD card image too. Test with freshly written card.