Using the keyboard to enable USB booting

Carlos Camargo cicamargoba at gmail.com
Thu Aug 27 12:28:39 EDT 2009


Reading the Jz4720 chip, I can see that all GPIOs have an internal Pull-up
resistor enabled at reset.

So, We need probe some Resistor values, if with a 330 resistor from KIN3 to
GROUND the processor enter in USB mode, you can try with 2k, 10k, etc


Carlos


On Thu, Aug 27, 2009 at 10:51 AM, Carlos Camargo <cicamargoba at gmail.com>wrote:

> Hi
>
> I'm testing in my board some resistors, with 1.8k form GND to Bootsel1 and
> a pull up 47k resistor the processor can enter to usb mode. So, I think that
> the problem is with the GPIO value at reset.
>
>
>
>
> On Thu, Aug 27, 2009 at 10:03 AM, Carlos Camargo <cicamargoba at gmail.com>wrote:
>
>> With the 330 resistor, the CPU enter in USB mode?
>>
>>
>>
>>
>> On Thu, Aug 27, 2009 at 9:29 AM, Adam Wang <adam at qi-hardware.com> wrote:
>>
>>> Hi Carlos,
>>>
>>>>
>>>> This board have a Reset S1, What happen when you press  the U key and
>>>> push the reset?
>>>>
>>>>
>>>>  Still enter NAND boot mode.
>>>
>>> Does cpu work on those KEYOUT1~7 and KEYIN1~7 as default "high" status
>>> before it starts to run codes to initial those pins, no matter either nand
>>> or usb?
>>
>>
>>
>> sorry, I don't know
>>
>>
>>>
>>> Adam
>>>
>>> _______________________________________________
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>>
>> Carlos
>>
>>
>>
>> --
>> Carlos Iván Camargo Bareño
>> Profesor Asistente
>> Departamento de Ingeniería Eléctrica y Electrónica
>> Universidad Nacional de Colombia
>> cicamargoba at unal.edu.co
>>
>
>
>
> --
> Carlos Iván Camargo Bareño
> Profesor Asistente
> Departamento de Ingeniería Eléctrica y Electrónica
> Universidad Nacional de Colombia
> cicamargoba at unal.edu.co
>



-- 
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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