embeded/ARM2015. 1. 9. 23:33

USB Recovery mode로 인해

SD나 MMC 부팅 실패시 USB 부팅모드로 넘어가게 된다. (기본값)

설정에 따라서는 USB 복구 모드를 끌수는 있으나 아무튼 기본값 -_-


이런 중요(!)한 내용이 왜.. cpu 관련 내용에는 없고

EVK 관련 내용에 있는걸까 -_-


12.13.4 USB Recovery Mode

USB boot mode is provided as a fail-safe mechanism for writing system firmware to the boot media. The boot mode is not usually entered by the normal methods of setting the boot pins or OTP, the other methods of entering USB boot mode are referred to generally as recovery mode.

An end user can manually start the recovery mode by holding the recovery switch for several seconds while plugging in USB. Holding the recovery switch is defined as reading the i.MX28 PSWITCH input as a 0x3. There are several switch circuits that will produce this input. The loader also automatically starts recovery mode if a nonrecoverableerror is detected from any boot mode other than USBdisabled completely. Attempts to enter USB boot mode through boot pins, OTP, or recovery methods will result in a chip power-down.


[링크 : http://cache.freescale.com/...=pdf&WT_ASSET=Documentation&fileExt=.pdf]


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