There are four (4) BOOT PINS according to the documentation of Freescale on the i.MX27:
<<BOOT [3:0] System Boot Mode Select—The operational system boot mode of the i.MX27/MX27L processor
upon system reset is determined by the settings of these pins. BOOT[1:0] are also used as
handshake signals to PMIC(VSTBY).>>
But, according to some auxiliary docs on evaluation boards, only a single PIN out of the four is actually used:
this single PIN seems to get used in order to differentiate bootstrapping from USB/UART and booting from NAND flash.
I'd like to ask you:
1) if you have any information on the remaining 3 PINs for booting ?
2) if you know how the bootstrap code that runs in internal ROM (iROM) works: as I understand it is used exclusively to bootstrap from UART/USB loading into NAND flash ? Is there a way to know what commands are understood by the iROM code ?
3) I have a legacy product on which a customised version of the "u-boot" bootloader is running: is there a freescale version of "u-boot" for the i.MX27 ?