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Archiver
05-17-2001, 01:49 AM
Does anyone out there have any experience reading a strain guage with
a stamp that can point me in the right direction? Thanks in advance
for any help.

Archiver
05-17-2001, 02:23 AM
I can give you an overview, I have used bridge type pressure
transducers. The strain gauge is a type of resistance bridge.

The differential voltage across the bridge is directly proportional
to the input to the bridge (weight, pressure, whatever). This is a
small voltage that is usually fed to a differential amplifier (op amp
usually) This takes the differential voltage and converts it to an
easier to manage ground referenced voltage. The diff amp output is
then amplified and scaled. What you're left with is a voltage that's
large enough to work with, that's directly proportional to the input
to the bridge.

Now for the stamp part:

The amplified and scaled diff amp output (as mentioned above) gets
fed to an A/D converter, which the basic stamp reads and processes.

For scaling, a reference voltage might be inputted to another A/D,
the stamp compares these voltages.

The bridge may generate a negative differential voltage (example:
applying vacuum to a pressure bridge) The stamp would need to
recognize this and deal with it.

Good Luck

Rich http://geocities.com/rbc1956


--- In basicstamps@y..., scott.huckerby@s... wrote:
> Does anyone out there have any experience reading a strain guage
with
> a stamp that can point me in the right direction? Thanks in
advance
> for any help.

Archiver
05-18-2001, 08:28 AM
Scott,
At the ESC show in SF Parallax had a demo that showed how to read a strain
gage bridge circuit with a BASIC Stamp. The setup used a Cirrus Logic CS5532
24-bit ADC chip. The Cirrus chip has a buildin op amp which is important for
mv outputs that you will be reading. Below is some pbasic code to illustrate
how this is done.
Hope this helps.
Chuck

'Program used to measure voltage analog data using a CIRRUS LOGIC CS5532, 24
bit ADC chip
'PARALLAX BS2p24 reads I/O data from the CS5532 connected to a MUSE M1101-20#
beam sensor
'See Crystal CS5531/32/33/34 Datatasheet (Oct '99) page 38, figure 16, for
connection setup
'4/27/01

dathi var word '16 bit high address
datlo var word '16 bit low address
x var word 'computed data value
y var word
y1 var nib
y2 var nib
y3 var nib
y4 var nib

SCLK con 15 ' ADC Clock
SDO con 14 ' ADC Data output
SDI con 13 ' ADC Data input
CS con 12 ' Chip select
p con 0

high CS
pause 50 'delay for crystal oscillator power up
low CS
gosub RESET
gosub LCDINIT
gosub CHIPINFO
shiftout SDI,SCLK,1,[%00001011] 'read configuration register 1
shiftin SDO,SCLK,0,[dathi\16,datlo\16]
' debug " CONFIG:",cr,"bits 31 to 16 ",bin16 dathi,cr,"bits 15 to 0 ",bin16
datlo,cr,cr

dathi=%0000000000000000 'write channel setup register 1
datlo=%0000000000000000
shiftout SDI,SCLK,1,[%00000101,dathi\16,datlo\16]

dathi=%0000000000000000 'write offset register 1
datlo=%0000000000000000
shiftout SDI,SCLK,1,[%00000001,dathi\16,datlo\16]

dathi=%0000010000000000 'write gain register 1
datlo=%0000000000000000
shiftout SDI,SCLK,1,[%00000010,dathi\16,datlo\16]

shiftout SDI,SCLK,1,[%00001101] 'read setup register 1
shiftin SDO,SCLK,0,[dathi\16,datlo\16]
' debug " SETUP:",cr,"bits 31 to 16 ",bin16 dathi,cr,"bits 15 to 0 ",bin16
datlo,cr,cr

shiftout SDI,SCLK,1,[%00001010] 'read gain register 1
shiftin SDO,SCLK,0,[dathi\16,datlo\16]
' debug " GAIN:",cr,"bits 31 to 16 ",bin16 dathi,cr,"bits 15 to 0 ",bin16
datlo,cr,cr

shiftout SDI,SCLK,1,[%11000000] 'contineous data conversion
lcdout p,1,["CIRRUS CS5532"]

REPEAT
shiftout SDI,SCLK,1,[%00000000]
shiftin SDO,SCLK,0,[dathi\16,datlo\16]

' debug " DATA:",cr,"bits 31 to 0 ",bin16 dathi,cr,"bits 15 to 0 ",bin16
datlo,cr
dathi=dathi<<8 'select bits 23 to 8 for measurement
datlo=datlo>>8
x=dathi+datlo
debug " Voltage ",dec x," counts (bits 23/8)",cr,cr
if x<38600 then over
x=38600
over:
y=((38600-x)*2)/33 'convert to pounds
x=y
x=y/100
y=(y-(x*100))
lcdout p,192,[dec x,".",dec1 y," pounds ·"]
pause 500
goto REPEAT

RESET 'initialize CS5532
shiftout
SDI,SCLK,1,[$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$F F,$FF,$FF,$FE]
dathi=%0010000000000000 'activate reset in configuration
register
datlo=%0000000000000000
shiftout SDI,SCLK,1,[%00000011,dathi\16,datlo\16]
return

LCDINIT 'initialize LCD
lcdcmd p,48 'set function
pause 5
lcdcmd p,48
pause 1
lcdcmd p,48
pause 1
lcdcmd p,32
pause 1
lcdcmd p,44
pause 1
lcdcmd p,8 'display off
lcdcmd p,12 'display on
lcdcmd p,6 'set mode
return

CHIPINFO
lcdcmd p,1
lcdout p,128,[" BASIC Stamp2P reads Cirrus Logic CS5532 "]
for x=1 to 24
pause 200
lcdcmd p,24
next
pause 1000
lcdcmd p,1
return

Archiver
05-27-2001, 02:36 AM
Dear list members,

I recently obtained several samples of the cirrus CS553x series of chips.
It appears to be available only in a SSOP package which is quite small.
What are the chances that I could successfully solder this chip to a pcb
board with a fine pitched iron?

thanks

---Steve

Archiver
05-27-2001, 04:42 AM
I've heard of people wrapping the tip of a small soldering iron with a small
gauge bare copper wire, which extends past the tip of the iron. This
effectively becomes the tip of a very small iron. The downside of this
approach is that the wire isn't able to deliver as much heat to the joint.
You have to take your time.

Good luck.

Arlen


----- Original Message -----
From: <sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=_xXUmG1CidtJLy1R-irvuo0LdeMY9U9WkqRdigV-mDWmwlBbuZA96MXOikCnpZ57-H6njSvbp2J-VQ)>
To: <basicstamps@yahoogroups.com (http://forums.parallaxinc.com/group/basicstamps/post?postID=xKG5Y0F2Iu3bTzyy8e0EkadGY9mwX_iHsnvOHs x4DkD6F6qhIVEBeAG4Hv8-CwR8Guv0W0rPKBufEqdYDsPD160e8_A)>
Sent: Saturday, May 26, 2001 10:36 AM
Subject: Re: [basicstamps] reading a Strain gauge with a stamp


> Dear list members,
>
> I recently obtained several samples of the cirrus CS553x series of chips.
> It appears to be available only in a SSOP package which is quite small.
> What are the chances that I could successfully solder this chip to a pcb
> board with a fine pitched iron?
>
> thanks
>
> ---Steve
>
>
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Archiver
05-27-2001, 06:08 AM
At 13:36 05/26/01, sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=f4YchoH4WzmpNAqyzI46iTP9eRjyaiPbXga-eSs0d9WAQqJqS_rQcrIGlmOyw60iE3aQzyxOZZ3D7g) wrote:

>I recently obtained several samples of the cirrus CS553x series of chips.
>It appears to be available only in a SSOP package which is quite small.
>What are the chances that I could successfully solder this chip to a pcb
>board with a fine pitched iron?


Hmmm... Assuming you're VERY comfortable with soldering in general, and
that the board is well masked, and you really know what you're doing, I
think this could be a bit of a stretch unless you can tolerate a few
do-overs. I think it can be done, but maybe not consistently. I fancy
myself very handy with an iron, even did MIL spec soldering for an
aerospace contractor for a while, and I wouldn't volunteer to take this on
if I had to hand solder with an iron and wire solder. I think this is case
calling for dabbing the pins lightly with an appropriate solder paste,
positioning very carefully on the pads and holding tightly in place while
you hit the pins with a pinpoint torch or hot air, in other words a
no-contact-required heating method. I'd definitely want a well masked
board that shed solder better than a well-oiled duck sheds water.

Jim H

Archiver
05-27-2001, 07:05 AM
sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=ssOdneh6P-2Si2EhhZqfoAxRndpDGE0M0LiEza7nBWN30ijJwFlzvhrkJLKc CT5a5UOgKpuzI1P3) wrote:
> I recently obtained several samples of the cirrus CS553x series of chips.
> It appears to be available only in a SSOP package which is quite small.
> What are the chances that I could successfully solder this chip to a pcb
> board with a fine pitched iron?
>
Try this:
Take the pins on the chip and bend alternate ones up and down (pin 1
up, pin 2 down, etc). This will give you a bit of room to solder.
Solder sort lengths of wire-wrap wire onto each pin. Solder the wires
to a 24-pin DIP header (e.g. Digikey part# A134-ND). That'll give you
a module that you can then plug into a regular DIP socket. Very handy
for prototyping.

SD


--
/================================================== =================\
| Steve DeGroof (http://degroof.home.mindspring.com/) |
\================================================= ==================/

Archiver
05-27-2001, 05:42 PM
From: sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=L4qHjhldjyJbKr62ct5HX0zSJTL3uX0swevu9D WgMqacGXgfYum6jX5Qq6YargN5IBmf9GM9sKfVLOzK)
To: basicstamps@yahoogroups.com (http://forums.parallaxinc.com/group/basicstamps/post?postID=r3wmjGWmQaQF0ZSPaE8AUTSLAoN4H5XtHWRBS9 Abyq2aF7fS4vEZ5jAWAJfT_AZ_qWNbznVq1Mj512NNt_6tht5m 9g)
Date: Sat, 26 May 2001 12:36:53 -0500

>I recently obtained several samples of the cirrus CS553x series of chips.
>It appears to be available only in a SSOP package which is quite small.
>What are the chances that I could successfully solder this chip to a pcb

Use a 12W iron with a 0.5mm tip, a tiny dab of solder paste on each pad, and
stick the chip down with a little blob of epoxy before you start. If you use a
jeweller's loupe and good light you should be OK.

Let pins cool before going over them again with a little more paste if they
need it.

--
Regards,

Derryck Croker

Archiver
05-27-2001, 08:18 PM
Steve,
Sure, it can be done, but it can be a tricky! I've done it with the MAX1112
and MAX186. What i did was to take a bit of vero-board, I used the one with
long strips of copper, but the one with isolated pads would be
better.......Never mind......a picture says more than a thousand words!

I just created a folder in the files section of this group on YAHOO! The
folder is called SSOP to DIL. In it there are three pics of the adapters
I've made.

I used a Metcal soldering iron with the smallest tip available and some very
thin tefloncoated wire. It so thin that the only way to remove the isolation
is to crush it with a pair of pliers and then pull it off like a banana
skin. I used a microscope at work but I guess it can be done with a good
magifyinglamp. Look at the pictures you see what I mean!
Good luck! You can do it!
/Henrik Olsson. Sweden.

----- Original Message -----
From: <sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=tC1-td0Ot0b83N7bDU5FveFCrs4ALNnh0lOlibJBvFpA20E-XwaSbOHM-ZKfC5Ke3RRmbJQP-kILiZgo)>
To: <basicstamps@yahoogroups.com (http://forums.parallaxinc.com/group/basicstamps/post?postID=2KpDx5JaFF20xVX6jb50L6r8LXflJ7APA1OcB8-PjRQlQaXjWU77ZhfsKMlWE_Nt7m-8n6clJqczfzzwSG8W2SnZn4875w)>
Sent: Saturday, May 26, 2001 7:36 PM
Subject: Re: [basicstamps] reading a Strain gauge with a stamp


> Dear list members,
>
> I recently obtained several samples of the cirrus CS553x series of chips.
> It appears to be available only in a SSOP package which is quite small.
> What are the chances that I could successfully solder this chip to a pcb
> board with a fine pitched iron?
>
> thanks
>
> ---Steve
>
>
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Archiver
05-28-2001, 08:11 AM
I have the same problem with maxim IC's. P/n 2480, a 1-wire driver comes in a
about 4mm square package and yet has 8 pins. I was thinking that there must
be ·some other way other than soldering. Any ideas?

Archiver
06-01-2001, 12:35 PM
Thanks to everyone for their ideas on soldering the CS553X chip, I'll try
it out this weekend.

-Steve







At 08:42 AM 05/27/2001 -0000, you wrote:
>From: sargent@s... (http://forums.parallaxinc.com/group/basicstamps/post?postID=FmQ66Cg8ZIO2zt3d5rOXLVrVa9MNPYis1dqzQT ZT1X8KCE0C_sbqnYHufqEb01It3i_xKKfl7bafkao)
>To: basicstamps@yahoogroups.com (http://forums.parallaxinc.com/group/basicstamps/post?postID=FpxKBwao0JxjgBbZR_hp8BuYSa7RGGOiddRxVn onSkbBeE4liLnh4i7elWiATQzRxDteJgpq7lZnOfA2xcvw2H98 ZtRN)
>Date: Sat, 26 May 2001 12:36:53 -0500
>
>>I recently obtained several samples of the cirrus CS553x series of chips.
>>It appears to be available only in a SSOP package which is quite small.
>>What are the chances that I could successfully solder this chip to a pcb
>
>Use a 12W iron with a 0.5mm tip, a tiny dab of solder paste on each pad, and
>stick the chip down with a little blob of epoxy before you start. If you
use a
>jeweller's loupe and good light you should be OK.
>
>Let pins cool before going over them again with a little more paste if they
>need it.
>
>--
>Regards,
>
>Derryck Croker
>
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>