Altimeter
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Posts: 46,084
I just thought I would let everyone know that i finished my Basic Stamp
pocket altimeter. I updated my page with code, schematic, pcb layout and
pictures of my new altimeter.
The one major problem i had to overcome was the equation for calculating
altitude. It is huge and has logs and anti logs. I first decided use a PAK
II for the calculations but when I decide to make a smaller version of my
altimeter there was no room.
Then I found out about linearization, and i got great result. Linearization
is made possible because the stamp is capable of linear math. Athough
implementing linearization takes quite a bit of code because you need many
linear equation it worked out nicely.
My altimeter has the following functions:
current pressure/altitude, max/min altitude, record altitude to a EEPROM
every second, display altitude data stored on EEPROM, and two calibrating
function manual and auto. The next version of the software i hope to have
ascent and decent rates.
If you interested you can check it out at
http://geocities.com/SiliconValley/Orchard/6633/altimeter.html
Shaun
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pocket altimeter. I updated my page with code, schematic, pcb layout and
pictures of my new altimeter.
The one major problem i had to overcome was the equation for calculating
altitude. It is huge and has logs and anti logs. I first decided use a PAK
II for the calculations but when I decide to make a smaller version of my
altimeter there was no room.
Then I found out about linearization, and i got great result. Linearization
is made possible because the stamp is capable of linear math. Athough
implementing linearization takes quite a bit of code because you need many
linear equation it worked out nicely.
My altimeter has the following functions:
current pressure/altitude, max/min altitude, record altitude to a EEPROM
every second, display altitude data stored on EEPROM, and two calibrating
function manual and auto. The next version of the software i hope to have
ascent and decent rates.
If you interested you can check it out at
http://geocities.com/SiliconValley/Orchard/6633/altimeter.html
Shaun
________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
Comments
Just as a matter of curiosity, what would have been your (and others)
reactions to a surface mount PAK-II? We supply surface mount parts on
special order now (which requires quite a few parts to be worthwhile).
However, if there was enough demand, we might make them a stock item.
Comments?
Regards,
Al Williams
AWC
* Interface a PS/2 keyboard to your Stamp or other microcontroller:
http://www.al-williams.com/awce/pak6.htm
>
Original Message
> From: Shaun Wilson [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=_QhQ_ecFZ1feqU1RcRQWEcYir7RF6fO61O8uP1xyj7QkaVUccKChWt20YvVwJd2YA1aXxbptpX0KReZIIFXzmBs]shaunwilson@h...[/url
> Sent: Thursday, July 13, 2000 6:49 PM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Altimeter
>
>
>
> I just thought I would let everyone know that i finished my Basic Stamp
> pocket altimeter. I updated my page with code, schematic, pcb layout and
> pictures of my new altimeter.
>
> The one major problem i had to overcome was the equation for calculating
> altitude. It is huge and has logs and anti logs. I first decided
> use a PAK
> II for the calculations but when I decide to make a smaller version of my
> altimeter there was no room.
>
> Then I found out about linearization, and i got great result.
> Linearization
> is made possible because the stamp is capable of linear math. Athough
> implementing linearization takes quite a bit of code because you
> need many
> linear equation it worked out nicely.
>
> My altimeter has the following functions:
> current pressure/altitude, max/min altitude, record altitude to a EEPROM
> every second, display altitude data stored on EEPROM, and two calibrating
> function manual and auto. The next version of the software i hope to have
> ascent and decent rates.
>
> If you interested you can check it out at
> http://geocities.com/SiliconValley/Orchard/6633/altimeter.html
>
> Shaun
> ________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
>
>
>
>
I did this several years ago to log alt and airspeed on model airplane
I guess since I selected a range of 0 to 3000 feet it was much easier
I used a similar baro sensor but at that time onboard signal conditioning
was not available. I used a double 741 (x1000) for op-amp
one was for alt the other was for dynamic pressure. I made measurements at
about 300 ft intervals and used a curve fitting program to give me a
polynomial so that I constructed my own calibration curve. The linear
transducer was very good. I believe that the linear model was not much
different that the 4th power polynomial. Did similar with dynamic ram
pressure to airspeed.
I achieved accuracy of 2 ft and .1 mph
I also simulated conditions with water u-tube manometer
I used a very clumsy 80C32 compared to the one chip computers we have now.
good luck
Richard
Original Message
From: "Shaun Wilson" <shaunwilson@h...>
To: <basicstamps@egroups.com>
Sent: Thursday, July 13, 2000 6:49 PM
Subject: [noparse][[/noparse]basicstamps] Altimeter
>
> I just thought I would let everyone know that i finished my Basic Stamp
> pocket altimeter. I updated my page with code, schematic, pcb layout and
> pictures of my new altimeter.
>
> The one major problem i had to overcome was the equation for calculating
> altitude. It is huge and has logs and anti logs. I first decided use a PAK
> II for the calculations but when I decide to make a smaller version of my
> altimeter there was no room.
>
> Then I found out about linearization, and i got great result.
Linearization
> is made possible because the stamp is capable of linear math. Athough
> implementing linearization takes quite a bit of code because you need many
> linear equation it worked out nicely.
>
> My altimeter has the following functions:
> current pressure/altitude, max/min altitude, record altitude to a EEPROM
> every second, display altitude data stored on EEPROM, and two calibrating
> function manual and auto. The next version of the software i hope to have
> ascent and decent rates.
>
> If you interested you can check it out at
> http://geocities.com/SiliconValley/Orchard/6633/altimeter.html
>
> Shaun
> ________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
>
>
>
>
>
You did an excellent job in building and presenting your altimeter. I
found it to be very helpful when I built my recording
altimeter/speedometer for by bicycle. With it I can log altitude and
speed every 36ft for rides up to 60miles. One advantage I have is
that I download the data after the ride and have Excel do all the
calibrations, calculations and graphing.
With serial eeproms being cheap, small and easy to use did you
consider creating a lookup table to convert to altitude. With a 64k
eeprom you could store all the altitudes that correspond to the 4,000
discrete levels you can achieve with your ADC. I assume you would
have to make some adjustment for the current pressure.
Hopefully when I get my altimeter/speedometer beyond the solderless
breadboard it is on now, I'll be able to present like you did with
your altimeter.
Jim Spencer