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ADXL3xx Accelerometers

Page history last edited by PBworks 13 years, 5 months ago

We just purchased 10 new ADXL300-series accelerometers on prototyping-friendly carrier boards from Sparkfun for CS247.

This document takes you through step-by-step instructions for connecting these accelerometers to d.tools.

 

Before you start, get familiar with the Basic Rules for working in the iRoom.

 

There are two models, which only differ in their sensitivity (learn more about g forces at Wikipedia):

 

The accelerometers live in a plastic drawer labeled "ACCELERO" on the soldering table in the iRoom:

 

The model number is written on top of the chip, in the second line:

 

Solder 0.1" headers onto accelerometer circuit board

You could solder wire directly to the accelerometer board, but it's a good idea, out of courtesy for others who will the accelerometer after you, to add a connector, so you can disconnect the cable.

 

The holes on the board have a standard spacing - 0.1". We have matching header pins that come in long strips in drawers ".1" HEADER" (straight version) and ".1" HDR ANGL" (90 degree angled version).

Take a single row strip of either kind and cut off four pins with a side cutter.

Insert the header pins into the holes from VDD (supply voltage - 5V in our case) through GND (ground), X, and Y. The chips we have do not sense acceleration in the Z-axis, so we don't need to connect it. The remaining "ST" pin is for a self test, which we won't need either.

 

Solder the pins in place - this is NOT a good time to practice soldering. The small surface mount accelerometer chip is heat sensitive and it is possible to overheat and kill it. Don't put the soldering tip to the pin/pad for more than 2 or 3 seconds at a time. Read more about our Soldering irons.

 

The final outcome should look like this:

 

 

Make a connecting cable

We'll make a 4-wire connecting cable from ribbon cable. The color coding of the ribbon cable will help you identify the different wires later on. Peel off four conductors, separate their ends about 1", and strip the insulation off about 1/4" using the 30 gauge hole of a wire stripper.

 

 

 

 

Next, we'll crimp on female pins that match the headers we soldered onto the board. You can find them in drawer labeled ".1" CRIMP PIN FEM". Break a few pins off. Insert one into the upper notch of the crimping tool, feed wire in, press down. Repeat. Read the Tutorial on crimping if you're unfamiliar with this operation.

 

 

Next, we'll have to insulate the pins from each other so they don't cause a short circuit. In drawer ".1" CONNECT HSNG" find a housing that fits four pins. Insert each crimped wire into a housing slot until you hear a faint "click" - the wires should now be locked in place.

 

 

slide the connector onto the header pins - we're 2/3rds done.

 

Each analog d.tools component board has a 3-pin connector with the following connections (from left to right, if pins are at the bottom of the board): GND, Vin(input signal), VDD (supply voltage - 5V).

 

We now have to match up the connections between the d.tools board and the accelerometer board - GND to GND, VDD to VDD, and X to Vin. But wait, what about the Y axis? You'll have to use a second d.tools component and only connect the middle pin to the Y axis. Repeat the crimping for the other end of the cable, then insert VDD,GND,and one axis into a 3pin housing in the correct order. CAUTION: you will have to flip the order of the wires accordingly or you could ruin your accelerometer. In my example, the order of wire colors from left to right on the accelerometer is: Black (Y), White (X), Gray (GND), Purple (VCC).

On the d.tools board, the order is: Gray (GND), White (X), Purple (VCC), with the Black wire going to the middle pin of another analogue d.tools component board.

 

Insert the small d.tools component boards into the large board, connect it to the PC, and watch your accelerometer data stream into Exemplar or Flash.

 

 

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