[Tinyos-help] Battery Voltage measurement

[fhg07 at c3sl.ufpr.br]

But from which channel does it read?
I mean, there are seven ! And I must get a reading from both channel seven
and channel one, in different events. Do you know how do I do that?



Thanks,
Fernando.

> Hi!
>
> On Mon, 20 Oct 2008, fhg07 at c3sl.ufpr.br wrote:
>
>> According to "MPR-MIB Users Manual":
>> "To compute the battery voltage:
>>   1. Set the BAT_MON processor pin (PA5/AD5) to HI.
>>   2. Program the application code to measure ADC Channel 7.
>>   3. Compute battery voltage, Vbatt, from Channel 7?s data by:
>>      Vbatt = Vref × ADC _ FS ADC _ Count
>>      where:
>>      Vbatt = Battery voltage
>>      ADC_FS = 1024
>>      Vref = External voltage reference = 1.223 V
>>      ADC_Count = Data from the ADC measurement of Channel 7"
>>
>> (This is for MICA2)
>>
>>
>> But how do I get this ADC_Count? Would that be what VoltageRead of
>> VoltageC returns? I am not sure about that, but the veracity of this
>> information is really  important. If anyone can affirm this or correct
>> me,
>> please answer.
>
> In tinyos-2.x the ADC_Count is what the Read.readDone from VoltageC
> returns. I attached a program that I use to verify this. When the MicaZ is
> plugged in the USB the value returned was 405 which corresponds to about
> 3V which seems reasonable.
>
> --
> Razvan ME