Accelerometers, microcontrollers, displays...

It's about 5 years since I was last here, so please forgive me if this is a FAQ.
I'm looking to build a 3-axis (or is that 6-axis?) accelerometer
that would produce output on a digital display. On a budget, of course!
I'd be grateful for any recommendations on (a) piezo-accel devices, (b) a suitable microcontroller to process the signals and (c) display units that could be used to show maybe 4" high digits [preferably LED but could be LCD].
Any thoughts?
Thanks in advance, Pete
--
"We have not inherited the earth from our ancestors,
we have borrowed it from our descendants."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is there a reason you want a piezo accelerator? These have their uses, of course, but the cheapest and most compact accelerometers tend to be MEMS-based units, which use micro-cantilevers. They also can register constant gravity, which piezo units cannot. Parallax, among others, sell a 3-axis model for under $40. It connects to a BASIC Stamp or most any microcontroller. Most of the digital output units these days have all the signal conditioning built in. The older accelerometers, or those made for high-end instrumentation, have analog outputs that you'd want to condition.
The interfacing to an LED would be through the microcontroller, and any can power a set of 7-segment displays. Digikey, among others, sell the 3-4" LED. You could also get a graphics LCD, but then you'd need a graphics library for your microcontroller, if you don't want to write it yourself. The 7-segment displays are much easier.
-- Gordon
snipped-for-privacy@nospam.demon.co.uk wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gordon McComb wrote:

You can also get wonderful LCD displays that have a 4-bit microcontroller interface. With a few lines of code, you can send it commands to display any ASCII character at anty position. They run at about 20 Euros / 25 US$.
Also, you need to decide if you want 3 or six accelerometers. If you go with 3, you can measure acceleration in all directions but nor rotation. You can get them in a single part on an easy to use carrier from Parallax.
If you want to use 6 accelerometers, you can also measure rotation, but you have to use 3 dual axis units and mount them at a distance. Again Parallax has those ready to mount. It you go with the bare chip, you'll have to use reflow soldering and know a bit about the external electronics required to drive the chip.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@matthiasm.com "Matthias Melcher" writes:
Thanks for the reply, Matthias.

No, I'm not interested in rotation (yet!) -- I just wasn't sure whether or not I'd need one or two accelerometers in order to measure +/- accelerations on each axis.

The less I need to know about external electronics the better. If there were a "Connecting accelerometers to microcontrollers for dummies" book I'd buy it!
Thanks, Pete
--
"We have not inherited the earth from our ancestors,
we have borrowed it from our descendants."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@NOrobotoidSPAM.com "Gordon McComb" writes:
Hi Gordon, Thanks for the reply.

None at all -- I'm basically a software person and just thought that piezo accelerometers would be cheaper/easier to interface/ easier to install. Obviously not -- thanks for the info!

I'll check out those -- my only experience in this area is with the 68HC11 many years ago and, apart from their rarity these days I'm sure they would cost a whole lot more than the simple sort of microcontroller I'd need to make this device (which will be used as a datalogger for a car). So long as it will do the job, the cheaper the better. As for the accelerometers, I wasn't sure whether this would require 3 or 6 sensors for full 3-axis measurement -- it appears from what you say that the Parallax device will do that.

Good to know; in my hardware ignorance I had assumed that the devices would output a voltage and that I'd need a microcontroller that had enough A/D pins.

"Easier" gets my vote :-) Time now to go looking on the 'net.
Thanks for the pointers,
Pete
--
"We have not inherited the earth from our ancestors,
we have borrowed it from our descendants."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@nospam.demon.co.uk wrote:

Check out http://www.sparkfun.com/
There are triple-axis accelerometers and dual-axis gyroscopes.

A/D pins are common. A PIC can have a lot; the 18F2620 has at least 12 A/D's. I prefer to use SPI.
--
D. Jay Newman ! Author of:
snipped-for-privacy@sprucegrove.com ! _Linux Robotics: Programming Smarter Robots_
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks everyone for the replies; I'll be doing some research on the Net this weekend, and maybe some shopping...
Pete
--
"We have not inherited the earth from our ancestors,
we have borrowed it from our descendants."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have used 7260Q Triple Axis accelermeter from freescale its great and easy to use. You can also select the G-range 1.5, 2, 4, 6 g.
http://www.sparkfun.com/commerce/product_info.php?products_id%2
I would just plug this into the ADC ports on an AVR combined with a serial lcd and you will have something up and running in no time at all.
Hope this helps. Michael
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
We designed in an Analog Devices ADXL210jqc but didn't needed it after all. I think they cost us about $20 each for 20 pieces.
The output is a PWM signal that can be read by a microcontroller without the need for sensitve Analog to Digital conversion circuitry.
http://www.analog.com/UploadedFiles/Data_Sheets/ADXL210E.pdf http://www.analog.com/en/prod/0,2877,ADXL210,00.html
-howy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.