Booting (bootstrapping) characteristics of i.MX27

[fstrati]

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 ?

[fstrati]

Thanks a lot, Igor

[igorpadykov · Accepted solution]

Hi Federico

boot selection is described in Table 4-28. System Boot Mode Selection

iROM commands are described in sect.8.4.1 Bootstrap Protocol

and Definition i.MX27 Reference Manual

http://www.freescale.com/files/32bit/doc/ref_manual/MCIMX27RM.pdf

There is no official "u-boot" for the i.MX27, as latest is Linux 2.6.22 with redboot on :

http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-process...

Best regards

igor

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