hi. I am curious about the whole boot up process. First, I talk about the hardware startup. Dc input–>clock start. Next the firmware startup. Bootrom–>cpu–>uboot–>kernel–>OS. Is the process start like this except the MCU? How about the MCU? Where does the boot rom stored? Am I missing anything? I want to know as detail as possible. I would appreciate it if anyone can help me out.
Yes, the booting process is right, you can check VIM2 Schematic for the details:
The MCU of VIMs is design to achive both power management and other purpuses.
I have seen this graphic in the Schematic. But they are in abbreviation. And I don’t understand some of the meaning. And I can’t find the definition of those abbreviation.
https://dl.khadas.com/Hardware/VIM2/Schematic/VIM2_V12_Sch.pdf
So your device still not working now, right?
No my device is working right now. But I am curious about it. I have downloaded this pdf document but I didn’t find the abbreviation meaning.
Might need some reading on the Schematic, and you can just post with detail question if you confuse on something 
What is the meaning of VCC_MCU, PWR_EN, VDDIO_AO18 / VCC1.8V, VDDQ_EMMC, VDD_EE, VDDIO_AO3.3V / VCC_3.3V?
Thanks
- VCC_MCU: Power for MCU
- PWR_EN: Enable signal for whole system
- VDDIO_AO18: 1V8 power for IO
- VDDQ_EMMC: Power for eMMC
- VDD_EE: Power for CPU core
- VDDIO_AO3.3V/VCC_3.3V: for 3.3V IO.