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Sorry, torow the pin 40 I can't drive the FET Q2 how I need the

I'm sorry for the disturb: between the pin 40, It's impossible to drive the 
FET Q2 how I need, for to change charge current .

Your solution, is the best.

Wich type of Fet you suggest me to use?


grazie 


On Thursday, February 13, 2014 5:39:27 PM UTC+1, Ytai wrote:
>
> Sorry, I can't really understand what you're asking / suggesting.
> Which pin 40 are you talking about and what exactly do you want to do with 
> it?
> I don't think the fuse can easily be destroyed. It is resettable.
>
>
> On Thu, Feb 13, 2014 at 6:15 AM, fabrio pellegrinetti 
> <[email protected]<javascript:>
> > wrote:
>
>> Thanks Ytai. 
>>
>> The solution you propose is very interesting. 
>> But is there a simpler solution? 
>> Is there a way to intervene by software to change the state of pin 40 of 
>> the PIC24F? 
>> I want to change the state of pin 40 to act on the FET Q2 so as to 
>> dynamically change the VBus. 
>> From java programming or modification to the firmware? 
>> Looking at the diagram IOIO-OTG, I noticed that one pin of switch_spdt is 
>> marked with "U4", but I can not find a match. 
>> Maybe I'll go OT: surely I've burned the fuse of ioio. 
>> Could you tell me what this fuse on the board and its spefifiche to buy 
>> new and replace it? 
>>
>> Thank you for the wonderful device that you created Ytai
>>
>> On Tuesday, February 11, 2014 5:48:38 PM UTC+1, Ytai wrote:
>>
>>> OK, I think I understand now. I don't think you need a digital 
>>> potentiometer for that. Look at the IOIO-OTG schematic and identify Q1. It 
>>> is a p-Channel FET responsible for the power supply on the VBUS line. When 
>>> the IOIO is in device mode, its gate is left floating, and thus gets pulled 
>>> up by R3 and the FET is not conducting.
>>>
>>> When in host mode, the PIC will pull the gate low through Q2 and R3. 
>>> According to the setting of R3, the gate voltage will vary, which can be 
>>> used to put Q1 in linear mode, so that it acts as a resistor on VBUS and 
>>> limits charging current.
>>>
>>> All you're missing, it being able to pull Q1's gate directly to GND in 
>>> order to supply full current when your main supply is up. You can probably 
>>> just extract a single wire from the leg of the chip, and connect it through 
>>> an n-FET to GND, where the n-FET gate will be driven by a signal that tells 
>>> you that your main supply is good.
>>>
>>>
>>> On Tue, Feb 11, 2014 at 2:23 AM, fabrio pellegrinetti 
>>> <[email protected]>wrote:
>>>
>>>> Thanks for the answers.
>>>>
>>>> let me try to explain better...what I would need on the ioio is to 
>>>> control the vbus with a digital potenziometer ioio embedded (controlled by 
>>>> java) instead of the standard one because I need to mantain the usb 
>>>> connection always active.
>>>> When the power line is present, I need to put via software the vbus at 
>>>> the maximum value for the android recharge, while when the power line is 
>>>> off the system needs to use the backup battery. In this case the vbus has 
>>>> to go to the minimum in order to continue to use the usb connection.
>>>>
>>>> So, I need an hardware change on the ioio.
>>>>
>>>>
>>>>
>>>>
>>>> On Friday, February 7, 2014 11:09:30 PM UTC+1, Ytai wrote:
>>>>
>>>>> Such a FET already exists in the IOIO-OTG, however, this will also 
>>>>> cause the USB connection to get dropped, which is I assume not what is 
>>>>> desired in this case.
>>>>> On Feb 7, 2014 9:06 AM, "Nishant Sood" <[email protected]> wrote:
>>>>>
>>>>>>  Fabrio,
>>>>>>
>>>>>> If you want to control charging of the android programmatically (in 
>>>>>> the hardware it cuts off only when full charge automatically) then I 
>>>>>> would 
>>>>>> suggest controlling the power going to the android controlled using a 
>>>>>> power 
>>>>>> mosfet switched programmatically when you sense the system has gone to 
>>>>>> battery backup
>>>>>>
>>>>>>
>>>>>> On Fri, Feb 7, 2014 at 10:28 PM, Ytai Ben-Tsvi <[email protected]>wrote:
>>>>>>
>>>>>>> I don't know if there's a programmatic way to disable charging on 
>>>>>>> the Android.
>>>>>>> What you *can* do, however, is detect the power fault condition and 
>>>>>>> put the phone to sleep. It should take very little current at this 
>>>>>>> mode, 
>>>>>>> assuming the battery was previously fully charged.
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Feb 7, 2014 at 7:49 AM, fabrio pellegrinetti <
>>>>>>> [email protected]> wrote:
>>>>>>>
>>>>>>>>
>>>>>>>> hello to all.
>>>>>>>> during the development of my home automation project, I came across 
>>>>>>>> the problem of the power supply of Android and ioio which must be 
>>>>>>>> separated. 
>>>>>>>> my board provide  power supply of 14V 2A with a transformer 220V to 
>>>>>>>> 14V and one backup battery of 1200mAh and 12V recharged from the 
>>>>>>>> transformer.
>>>>>>>> When the the power line is off, the battery must supply power at 
>>>>>>>> the ioio, but he mustn't to the android.
>>>>>>>> For now I use Y split cable power supply double USB A and one usb 
>>>>>>>> micro.
>>>>>>>>  
>>>>>>>> Micro usb connected to the android, first usb to ioio and second 
>>>>>>>> usb to  another  standard android power supply. the poteziometer Vbus 
>>>>>>>> is 
>>>>>>>> set to minimum in accord to the usb debug survey.
>>>>>>>> Problem is  when the system goes on battery the an amount of mA 
>>>>>>>> goes to the standard android power supply and this reduce backup 
>>>>>>>> battery 
>>>>>>>> charge
>>>>>>>> What I would like is to be able to check the current Vbus, from 
>>>>>>>> java code from a ioio embedded digital potenziometer.
>>>>>>>>
>>>>>>>> so when detect power failure, I can dinamically reduce Vbus current.
>>>>>>>>
>>>>>>>> thanks
>>>>>>>> best regards
>>>>>>>>
>>>>>>>> fabrio
>>>>>>>>
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>>>>>>
>>>>>>
>>>>>> -- 
>>>>>> *Thanks & Regards,*
>>>>>>
>>>>>>  *Nishant Sood*
>>>>>> *--*
>>>>>> *CEO and Founder*
>>>>>>
>>>>>>  *Winacro Innovation's Inc.*
>>>>>> *----------------------------------------*
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>

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