Accelerometers, microcontrollers, displays...

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

-- Gordon

snipped-for-privacy@nospam.dem>

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.

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

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

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.

Hope this helps. Michael

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.

-howy

Check out

A/D pins are common. A PIC can have a lot; the 18F2620 has at least

Thanks everyone for the replies; I'll be doing some research on the Net this weekend, and maybe some shopping...

Pete