[Tinyos-help] Reading voltage levels

Eric Decker cire831 at gmail.com
Wed Dec 4 23:47:50 PST 2013


Sorry.  I oppologize profusly :-)

I've been living with this stuff for a number of years and it is easy to
forget how confusing the TI manuals are...

more below.



On Wed, Dec 4, 2013 at 10:25 PM, Alaios <alaios at yahoo.com> wrote:

> Hi
> as manual I guess you mean this one
>
> http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slas368g
>

No that is the data sheet.   Which you should also have handy and refer to
often.   That describes the actual implementation of one of the members
(actually a group of like chips that are very close to each other).   All
of the chips that make up a given family are described by the User's Guide
which I keep referring to as "The Manual"  Sorry about that too, I should
be more specific.

If you look at the front page of datasheet (which you reference above as
SLAS368g, SLAS368 is the lit number and G is the revision), you will see...

 For Complete Module Descriptions, See the
MSP430x1xx Family User’s Guide,
Literature Number SLAU049

You do indeed want SLAU049, actually the current version is
SLAU049F<http://www.ti.com/lit/ug/slau049f/slau049f.pdf>,
note I stuffed the pointer too).   And in particular you want to read
Chapter 17, ADC12.   The TelosB uses the msp430f1611 which includes an
ADC12, not to be confused with the ADC10.


>
> at page 42. It would be easier for me to apprehend it if there was more
> text there. I still luck all this low level understanding but somehow I
> will make it.
>

Just wait till you try to make sense of the TinyOS ADC code :-).

But it starts with getting a good understanding of what you have to work
with, ie. the basic h/w.

Just wait until you start to do full scale system design where you get to
make it all up.  :-)   Lots of fun.



>
> Regards
> A
>
>
>
>   On Wednesday, December 4, 2013 10:40 AM, Eric Decker <cire831 at gmail.com>
> wrote:
>
>
>
> On Tue, Dec 3, 2013 at 10:05 PM, Alaios <alaios at yahoo.com> wrote:
>
> Hi all,
> I am using telosb with msp430 processor. If I understood it right the ADC
> channels can be set to work with either 1.5 or 2.5Volts maximum.
>
>
> Like I said you need to read the user manual.
>
> The 1611 provides an internal voltage reference of 1.5V or 2.5V.  But you
> can also use an external reference voltage.
>
> If you need 3.3 or 3.0 voltages as input then you need to provide an
> external voltage reference and then need to program the ADC
> h/w appropriately.  The ADC inputs can be driven from 0-AVCC which
> typically is the same as the digital VCC and they get tied together.
>
> If you can work with 2.5 volts then you can use the internal reference.
>
>
> Seriously, read the manual.
>
>
>
>
> ADC is 12 bits so any voltage between 0 and maximum voltage would be
> mapped to these 12bits. I will need later to do the maths and see if that
> can give me mV resolution that the sensor needs.
>
> Regards
> Alex
>
>
>
>   On Wednesday, December 4, 2013 4:49 AM, Eric Decker <cire831 at gmail.com>
> wrote:
>
> The MDA300CA that Bipin mentions in its data sheet that the ADC inputs are
> 0-2.5 V so don't know if that works for your application.
>
> The telosb has a few ADC ports brought out to the expansion connector at
> U2.   I beleive you can use those for 0-3V.
>
> you should look at the manual for the msp430f1611 mcu.
>
>
>
> On Tue, Dec 3, 2013 at 12:04 AM, Alaios <alaios at yahoo.com> wrote:
>
> Dear all,
> I am practicing on connecting external sensors on a telosb or micaz
> sensors and I need a bit of your experience.
>
> One of the sensors  I found on the market, that I would like to try, can
> work with 3Vdc (which I think is supported by telosb).
>
> The pressure reading would be returned of voltage values ranging from 0 to
> 3 Volts.
> Which are the interfaces that can "understand" voltage values?
>
> I would like to thank you in advance for your reply
>
> Regards
> Alex
>
>
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>
>
>
> --
> Eric B. Decker
> Senior (over 50 :-) Researcher
>
>
>
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>
>
>
>
>
> --
> Eric B. Decker
> Senior (over 50 :-) Researcher
>
>
> _______________________________________________
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>
>
>


-- 
Eric B. Decker
Senior (over 50 :-) Researcher
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