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

[Juan Antonio López Riquelme]

Hi,

thank you, i not see this pins before, i only see .h file and i believe that
tmote can use reference negative, i am sorry.

If you see the  schematic, VeREF+ is connect to ADC0 in expansion connector,
maybe if you provides negativa power in ADC0 line you can convert values
from -power to 0, buy you also need positive values, i believe that is more
easy scaling to positive values the output of you device before of connect
to tmote.

A greeting,
Juan Antonio.


2007/5/1, Oussama Chougna <o.chougna at phi-i.com>:
>
>  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
>
>
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> Tinyos-help at Millennium.Berkeley.EDU
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>
>
>
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