Using the keyboard to enable USB booting

Adam Wang adam at
Thu Aug 27 09:22:43 EDT 2009

Carlos Camargo wrote:
> On Thu, Aug 27, 2009 at 3:31 AM, Adam Wang <adam at 
> <mailto:adam at>> wrote:
>     Hi Carlos,
>     It does not work for me.
>     I tried to:
>     place a 330 Ohm between KEYIN3 and GND, connect BOOT_SEL1(should
>     be SEL1 to select USB boot) to KEYOUT7, also have a pull-up R5 10K.
>     I found KEYOUT1~7 are normal low; when push "U" key, the KEYOUT7
>     will have a pulse with 50us high to scan during NAND boot mode.
>     the KEYIN1~7 are normal high; when push "U" key, the KEYIN3
>     measurement is the same as KEYOUT7.
> In this case the processor enter to USB mode?
That case is in the NAND boot mode.
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