This procedure is also described in several MSP430 application notes.
Somewhere in the group posts from years back I posted a document called
APP14306.doc or zip.
Al
On 9/03/2014 12:37 PM, a...@granzeier.com wrote: > The BASIC Stamp (and the Atmel AVRs through BASCOM
AVR) has a psuedo
> analog input where you tie the pin through the unknown resistance, and
> then through a known capacitor and to ground. The pin is turned to an
> output port for a certain amount of time (long enough to charge up the
> capacitor) and then it is turned to an input - the computer counts the
> amount of time that it takes the input to go from 1 (capacitor is
> charged) back to a 0 (capacitor is discharged.) This time is related
> to the RC time constant which can be used to determine an unknown
> resistance (or an unknown capacitance when given a known resistance.)
>
> You can try using this on any digital port pin.
>
> Good luck with this.
> ---In m..., wrote :
>
> I am new to MSP. i want to design an Ohm meter using MSP 430. Can
> anyone suggest how do I start...
>
Reply by art3...@granzeier.com●March 8, 20142014-03-08
The BASIC Stamp (and the Atmel AVRs through BASCOM AVR) has a psuedo analog
input where you tie the pin through the unknown resistance, and then through a
known capacitor and to ground. The pin is turned to an output port for a
certain amount of time (long enough to charge up the capacitor) and then it is
turned to an input - the computer counts the amount of time that it takes the
input to go from 1 (capacitor is charged) back to a 0 (capacitor is discharged.)
This time is related to the RC time constant which can be used to determine an
unknown resistance (or an unknown capacitance when given a known resistance.)
You can try using this on any digital port pin.
Good luck with this.
---In m..., wrote :
I am new to MSP. i want to design an Ohm meter using MSP 430. Can anyone
suggest how do I start...
Reply by Onestone●March 8, 20142014-03-08
The sad thing is you can't always blame the students. I've often
wondered how an EE degree can be granted when the 'engineer' has no
clue
what switch bounce is, or why you might need to decouple A/D references
etc, then I met the recently retired head of the electronicss and
computing department at a local uni. he was one of my on the job
trainees grandfather, said trainee was a senior engineer in the company,
i was hired in to design a fleet management system, and was teaching the
in house guys RF and GPS, so not part of the team. the trainee then
arranged to have his grandfather hired as an 'auditor' of my work. Now
this design had been out in the field for many months by this time,
without a single problem other than dump truck drivers kicking the gps
and RF antennas to oblivion, so it worked extremely reliably, something
like a 99.7% packet success rate over the entire period. The display
also worked like a charm. A display I'd been using for about 4 years. So
in he comes, looks at a few data sheets then declares that my design was
dangerously inept, and that I'd totally bolloxed up the display
interface (which comprised a single 74HCT14), It needed a state machine
implementing in a CPLD apparently, I told him he was wrong, pointed out
the flaws in the data sheet he was reading but he was adamant (state
machines were the trendy thing at the time), so they borrowed my $1600
programming device, redesigned the board, and never returned my gear. I
refused to go along with this, because it didn't need it, and I tied
explaining that the redesign wouldn't work, so i got fired, they hired
in a PCB design expert, who was more spurt than X, who took 5 months to
do the layout, and messed it up so badly if you closed the case the PCB
would burn out in seconds rather than minutes. Finally they came to fire
up the circuit and of course the display didn't work. Eventually I was
paid enough to return for what was left of one day, reprogrammed the
CPLD to act like a 74HCT14 and bingo it worked again. The layout guy had
a degree, the ex lecturer had a doctorate and was a professor, and the
guy who fired me had a doctorate too. That was probably about the time I
lost all faith in the higher education system, because if the head of a
university department can make such elemental mistakes what hope do his
students have?
Were I to hire a freshly graduated student now I think I'd lock them in
a room for a month listening to Black Sabbath and Hawkwind turned up to
11 and playing at 78 until they were brainwashed, then let them start
out fresh and new!
that said my youngest son is at uni on the third year of a psychology
degree, a subject I feel to be 2 rungs below witch doctoring, so i can't
really whine!
Al
On 9/03/2014 10:36 AM, r...@yahoo.com wrote: > I think it took me less than a minute to find a dozen
or more
> references via google that, essentially, answer the question, short of
> the actual code for a specific device and a pcb layout... It's just
> not that hard.
> I have similar issues with the Nursing Students I teach. Many don't
> seem to want to reason anything out for themselves; they just want a
> packaged answer. Oh, and don't forget, a healthy paycheck for not
> having to think it through... Me: So, why are you giving this med to
> the patient? Them: The doctor ordered it. Me: Why did the MD order
> it? Them: Uhm.... I don't know?
> Makes me cringe. So it goes...
>
> Bob
Reply by rdun...@yahoo.com●March 8, 20142014-03-08
I think it took me less than a minute to find a dozen or more references via
google that, essentially, answer the question, short of the actual code for a
specific device and a pcb layout... It's just not that hard.
I have similar issues with the Nursing Students I teach. Many don't seem
to want to reason anything out for themselves; they just want a packaged answer.
Oh, and don't forget, a healthy paycheck for not having to think it
through... Me: So, why are you giving this med to the patient? Them: The doctor
ordered it. Me: Why did the MD order it? Them: Uhm.... I don't know?
Makes me cringe. So it goes...
Bob
Reply by Onestone●March 8, 20142014-03-08
It's a sad reflection on our education systems too that they seem to
largely condone this sort of excercise. Yet many years ago in this
industry (I'm going back here to the early to mid 70's and probably
through to the late 80's) your ability counted for an awful lot more
than any paper you might flash around. Whiloe having both of course was
a shoe in!
Al
On 9/03/2014 9:32 AM, Peter Johansson wrote: > On Sat, Mar 8, 2014 at 3:08 PM, Onestone
wrote:
>
>> Does it matter, the formula is (or was) usually given as V=IR, if you
>> can't organise that to find any of the terms given any 2 then you
really
>> shouldn't be doing this stuff.
>>
>> Or am I just old fashioned?
> Sadly, it seems as if the current generation has not learned how to
> search for information or is too lazy to do so. Fortunately, they
> cannot be bothered with e-mail either, and these types of questions
> (i.e. those that can be easily answered with a simple google search)
> have come to dominate many web-based forums.
>
> -p.
>
>
>
Reply by Peter Johansson●March 8, 20142014-03-08
On Sat, Mar 8, 2014 at 3:08 PM, Onestone wrote:
> Does it matter, the formula is (or was) usually given
as V=IR, if you
> can't organise that to find any of the terms given any 2 then you
really
> shouldn't be doing this stuff.
>
> Or am I just old fashioned?
Sadly, it seems as if the current generation has not learned how to
search for information or is too lazy to do so. Fortunately, they
cannot be bothered with e-mail either, and these types of questions
(i.e. those that can be easily answered with a simple google search)
have come to dominate many web-based forums.
-p.
Reply by Onestone●March 8, 20142014-03-08
Does it matter, the formula is (or was) usually given as V=IR, if you
can't organise that to find any of the terms given any 2 then you really
shouldn't be doing this stuff.
Emmett Redd Ph.D. mailto:E...@missouristate.edu
Professor (417)836-5221
Department of Physics, Astronomy, and Materials Science
Missouri State University Fax (417)836-6226
901 SOUTH NATIONAL Lab (417)836-3770
SPRINGFIELD, MO 65897 USA Dept (417)836-5131
In statesmanship get the formalities right, never mind about the moralities. --
Mark Twain.
________________________________________
From: m... [m...] On Behalf Of Peter Johansson [r...@gmail.com]
Sent: Saturday, March 08, 2014 5:15 AM
To: m...
Subject: Re: [msp430] ohm meter using msp430
In Sat, Mar 8, 2014 at 4:06 AM, ANAND SAI VERMA wrote:
> can you elaborate..
All you can measure directly with an MSP430 (or any microcontroller,
for that matter) is voltage.
Can you think of a way to take a voltage measurement and compute an
unknown resistance from it?
