Humidity chip
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Posts: 46,084
Hi,
I'm currently trying to use a stamp 2sx to get a reading for
temperature and humidity from a sensirion SHT71 for a college
project. I am just wondering if anyone would have any code or links
to code that would work for this. The code im using is from
www.emesystems.com but it is not working or else my chip is broken.
Any help would be greatly appreciated.
Yours Sincerely,
Fearghal O'Connor
I'm currently trying to use a stamp 2sx to get a reading for
temperature and humidity from a sensirion SHT71 for a college
project. I am just wondering if anyone would have any code or links
to code that would work for this. The code im using is from
www.emesystems.com but it is not working or else my chip is broken.
Any help would be greatly appreciated.
Yours Sincerely,
Fearghal O'Connor
Comments
http://www.emesystems.com/OL2sht1x.htm
Be sure you have the pullup resistor on the sda line. Also,
Sensirion now recommends a pulldown resistor on the sck line, in
order to avoid an occasional lockup when the power supply does not
come up cleanly.
There is also data on the Parallax web site:
http://www.parallax.com/dl/src/prod/sht%20docs%20code.zip
and Jon Williams' N&V article
http://www.parallax.com/dl/docs/cols/nv/vol3/col/91.pdf
http://www.parallax.com/dl/docs/cols/nv/vol3/code/91.BS2
-- Tracy
http://www.emesystems.com
>Hi,
> I'm currently trying to use a stamp 2sx to get a reading for
>temperature and humidity from a sensirion SHT71 for a college
>project. I am just wondering if anyone would have any code or links
>to code that would work for this. The code im using is from
>www.emesystems.com but it is not working or else my chip is broken.
>Any help would be greatly appreciated.
> Yours Sincerely,
> Fearghal O'Connor
site. You should be able to start with it and work forward.
http://www.parallax.com/detail.asp?product_id=28018
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: fearghaloconnor [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=kRhGxQG6qtG2E6DghgtlpzBHu_hfzvq6uyJpcoQWBR5U9QqP5hvu4KP_VePQgkKUahj__iklQ_pnGD7NMdAAtaY]fearghaloconnor@y...[/url
Sent: Tuesday, December 02, 2003 1:45 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Humidity chip
Hi,
I'm currently trying to use a stamp 2sx to get a reading for
temperature and humidity from a sensirion SHT71 for a college
project. I am just wondering if anyone would have any code or links
to code that would work for this. The code im using is from
www.emesystems.com but it is not working or else my chip is broken.
Any help would be greatly appreciated.
Yours Sincerely,
Fearghal O'Connor
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The code on Tracy's site works for sure. I would triple check to make sure
you have it hooked up correctly. Are you using the same pins as the site
describes? If not you need to change the code in three places, if I remember
correctly. What exactly is happening when you try to use the sensor?
Jonathan
www.madlabs.info
Original Message
From: "fearghaloconnor" <fearghaloconnor@y...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, December 02, 2003 11:44 AM
Subject: [noparse][[/noparse]basicstamps] Humidity chip
> Hi,
> I'm currently trying to use a stamp 2sx to get a reading for
> temperature and humidity from a sensirion SHT71 for a college
> project. I am just wondering if anyone would have any code or links
> to code that would work for this. The code im using is from
> www.emesystems.com but it is not working or else my chip is broken.
> Any help would be greatly appreciated.
> Yours Sincerely,
> Fearghal O'Connor
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
I posted a message on the basicstamp group page a
number of weeks ago inquiring about youre code for the
Sht 1x/7x on http://www.emesystems.com/OL2sht1x.htm. I
still have one or two questions regarding your code.
For reasons unknown, my pin 1 doesnt work so I need to
use a different pin for the data line. Is there other
places in the code that will need changing? Also there
are two different diagrams on the page for the set up
of the resistors connected, do I need the resistor in
series on the p0 line, and do I need the capacitor
between Vdd and Vss? Will the code work for both sht1x
and sht7x? I look forward to hearing from you because
this humidity sensor is causing me severe difficulty.
Yours Sicerely,
Fearghal O'Connor
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> I posted a message on the basicstamp group page a
>number of weeks ago inquiring about youre code for the
>Sht 1x/7x on http://www.emesystems.com/OL2sht1x.htm. I
>still have one or two questions regarding your code.
>For reasons unknown, my pin 1 doesnt work so I need to
>use a different pin for the data line. Is there other
>places in the code that will need changing? Also there
>are two different diagrams on the page for the set up
>of the resistors connected, do I need the resistor in
>series on the p0 line, and do I need the capacitor
>between Vdd and Vss? Will the code work for both sht1x
>and sht7x? I look forward to hearing from you because
>this humidity sensor is causing me severe difficulty.
> Yours Sicerely,
> Fearghal O'Connor
You need to change two pin definitions in order to use p2 instead of p1:
dta con 2 ' for SHIFT commands
dtain var in2 ' as input for conversion-done flag
I should update that page and program soon to PBASIC 2.5. Under
PBASIC 2.5, the separate definitions become rolled into one,
dta PIN 2
As far as the schematic is concerned, you certainly need the pullup
resistor to +5 volts. Also the resistor (200 or 330 ohms, not
critical) in series in the dta line is necessary to avoid contention
when both the Stamp and the chip are outputs at the same time. The
resistor in series with the sck line is only for good measure.
Sensirion now recommends a pulldown resistor (4.7 kohm or 10k, not
critical) from the sck line to common. (Note pulldown, not pullup!).
Without that resistor, in rare cases when the power comes up with
noise, the interface will not initialize correctly. Don't forget the
capacitor. Here it is, then:
' STAMP SENSIRION
' 330 ohm isolation, optional
' p0
/\/\---o--pin 3 sck, clock
' ;---/\/\
' pull-down, optional
' | 4.7k
' Vss--o-o
pin 1 common
' | 330 ohm isolation, required
' p1
/\/\---o--pin 2 dta, data
' |
' === 0.1uf or larger
' |
' o---/\/\
' pull-up, required
' | 4.7k
' Vdd--o
pin 4 +5 volts
The program works for the sht1x and for the sht7x. Be careful, and
observe that the '7x has a different pinout.
-- Tracy