[Tinyos-help] Battery Voltage measurement

[Razvan Musaloiu-E.]

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
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