Using the keyboard to enable USB booting

Carlos Camargo cicamargoba at gmail.com
Thu Aug 27 06:45:36 EDT 2009


On Thu, Aug 27, 2009 at 3:31 AM, Adam Wang <adam at qi-hardware.com> 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?


>
> but if place 330 Ohm between KEYIN3 and GND, will get a very low
> voltage(~0.1V) via divider with pull high resistor when push "U" key. And
> will let KEYIN3 have no detection high pulse from KEYOUT7 during normal boot
> mode.
>
> Did I do anything wrong or is there any other way?
> Thanks,
> Adam
>
> Carlos Camargo wrote:
>
> Hi Adam
>
>
> Many  MP4 devices use resistor for that.
>
> What do you think about this? :
>
>
> Place a resistor between KEYIN3 and ground (so is necessary that you rotate
> a "1"  in KEYOUT[1:7]), connect BOOT_SEL0 directly to KEYOUT7, and to the
> pull-up resistor.
>
> In normal operation, if you rotate a "1" in the keyout you read "0" in
> KEYIN3 if you don't press any key  (S18-S25)  because of resistor, if the
> user press any key (S18-S25) you can read "1"  in this line.
>
>
> At boot time if you press the key "U" you connect BOOT_SEL0 to "0"  via
> resistor, for this is necessary that the ground resistor will be small that
> the pull-up resistor. There is a resisitive voltaje divider with Rpull-up
> and Resistor to ground. This make sense for you?
>
>
> Carlos
>
>
> On Wed, Aug 26, 2009 at 9:45 PM, Adam Wang <adam at qi-hardware.com> wrote:
>
>> Hi,
>>
>> I need help with a change to the NanoNote board. I want to route the boot
>> pins from the CPU (BOOT_SEL0/pin146 and BOOT_SEL2/pin145) so that you can
>> just press the 'u' key<KEYOUT7, GPC16 & KEYIN3, GPD20> when pressing the
>> power ON button to enable USB booting.
>>
>> Unfortunately BOOT_SEL0 needs to be GND and I don't have a good idea how
>> to easily connect the boot pins into the keyboard.
>>
>> Does anybody have an idea?
>>
>> http://github.com/adamwang
>> http://downloads.qi-hardware.com/hardware/qi_avt2/sch/
>>
>> Thanks,
>> Adam
>>
>>
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>
>
>
> --
> Carlos Iván Camargo Bareño
> Profesor Asistente
> Departamento de Ingeniería Eléctrica y Electrónica
> Universidad Nacional de Colombia
> cicamargoba at unal.edu.co
>
> ------------------------------
>
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>
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-- 
Carlos Iván Camargo Bareño
Profesor Asistente
Departamento de Ingeniería Eléctrica y Electrónica
Universidad Nacional de Colombia
cicamargoba at unal.edu.co
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