[Tinyos-help] can Tmote sky ADC port be used to measure negativevoltage

[Juan Antonio López Riquelme]

Thank you Cory,

your reply explain why pin VeREF connect to ground.

A greeting,
Juan Antonio.


2007/5/1, Cory Sharp <cory at moteiv.com>:
>
> If you read in the MSP430x161x data sheet, in the section "12-bit ADC,
> external reference", the minimum allowable voltage into VeREF- is 0V.
>
> Cheers,
> Cory
>
> On 5/1/07, Oussama Chougna <o.chougna at phi-i.com> wrote:
> >
> >  Antonio,
> >
> >
> >
> > The settings for an ADC port are defined in MSP430ADC12.h header file.
> >
> > As the negative reference voltage you can specify VeRef-, but in the
> > TMote Sky datasheet schematics you can clearly see that the VeRef- pin of
> > the MSP430 is soldered to ground.
> >
> > It is moteiv's design and too bad.
> >
> >
> >
> > So programming will take no effect on this.
> >
> >
> >
> > Ground stays zero, so you cannot do conversions between -2,5V and 2,5V.
> > But you can between 0 and 2,5V.
> >
> >
> >
> >
> >
> > Greeting,
> >
> >
> >
> >
> >
> > oussama
> >
> >
> >  ------------------------------
> >
> > *From:* Juan Antonio López Riquelme [mailto:ja.lopez.riquelme at gmail.com]
> >
> > *Sent:* dinsdag 1 mei 2007 13:16
> > *To:* Oussama Chougna
> > *Cc:* yicheng; tinyos-help at millennium.berkeley.edu
> > *Subject:* Re: [Tinyos-help] can Tmote sky ADC port be used to measure
> > negativevoltage
> >
> >
> >
> > Hi Yicheng and Oussama,
> >
> > if you read TEP101 (appendix A) then you can know that the conversion
> > reference is programable.
> >
> >
> >
> > For use ADC i supose that you use a components in the folder
> > C:\cygwin\opt\tinyos-2.x\tos\chips\msp430\sensors of template and modify
> > the fields of struct for use an ADC of expansion port.
> >
> >
> >
> > You also can change values of fields two (sref) and three (ref2_5v) with
> > the options that appear below in the same file (C:\cygwin\opt\tinyos-
> > 2.x\tos\chips\msp430\adc12\Msp430Adc12.h ).
> >
> >
> >
> > A greeting,
> >
> > Juan Antonio.
> >
> >
> >
> >
> >
> > 2007/5/1, Oussama Chougna <o.chougna at phi-i.com >:
> >
> > Hi,
> >
> >
> >
> > I have this problem too.
> >
> > If you check the schematics in the TMote Sky datasheet, you will see
> > that the negative reference voltage pin is grounded.
> >
> > So you can measure only between 0 and any value.
> >
> >
> >
> >
> >
> > oussama
> >
> >
> >  ------------------------------
> >
> > *From:* tinyos-help-bounces at Millennium.Berkeley.EDU [mailto:tinyos-help-bounces at Millennium.Berkeley.EDU]
> > *On Behalf Of *yicheng
> > *Sent:* woensdag 25 april 2007 20:53
> > *To:* tinyos-help at Millennium.Berkeley.EDU
> > *Subject: *[Tinyos-help] can Tmote sky ADC port be used to measure
> > negativevoltage
> >
> >
> >
> > Hi,
> >
> >
> >
> > Just want to know if negative voltage (like -1.5v) can be measured by
> > any Tmote sky ADC port? If yes, how can I do it? Do I need to set a negative
> > reference voltage?
> >
> >
> >
> > Thanks!
> >
> > Yicheng
> >
> >
> > _______________________________________________
> > Tinyos-help mailing list
> > Tinyos-help at Millennium.Berkeley.EDU
> > https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> >
> >
> >
> >
> > _______________________________________________
> > Tinyos-help mailing list
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> >
> >
>
>
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