MachineGrid::Robots at Work

Soldering Your Accelerometer – The ADXL202E

I finally get my hands on Analog Devices’ accelerometer- the ADXL202E. It’s small,very small.
See what I mean!

However there’s this problem, I usually work on PDIP packages and SMDs do give me a scare,not because I’ve never soldered them,but because I do not have the necessary equipment for it. So I decide to do my thing , and also take a little inspiration from Sparkfun’s Breakout board.

My first step was to find a thinner tip for the soldering iron. It presently has a standard tip,too big to solder the accelerometer. I decide to go shopping for a thinner one and get the finest one available at my local shop.
This is what the tip looks like[It's standard, I need a thinner one]

This is the new tip.

Since I needed to get wires out from the ADXL202 , I used very thin ones.You can easy get these by removing the insulation off normal wires you use in breadboarding. Now comes the difficult part – soldering.

First you need to hold your chip in place.With a little tape,firmly place the accelerometer on the table your working on.

This will prevent the chip from moving around ,when you solder the wires

First, put a little solder on one of the accelerometer’s solder points.Then taking a wire ,heat the wire, add some solder and touch it to the sensor’s pads. Do the same for the other seven “pins” of the sensor This is how it looked when done.[I know it's gory and ugly,but it's the best I could do]

Here’s the top view.

Now to mount the sensor onto a PCB. I chose a simple general purpose PCB[ dot matrix], as it’s easy available.That’s a One Ruppee coin,Indian currency ,the board is next to.

I cut the PCB to half to get a smaller footprint,that will house the ADXL202 and the supporting components. This is the finished version of the board:

If you notice,there are pins at the bottom of the board.These are for the signal and supply lines.I put them ,so that the board can piggy back on a bigger PCB housing the microcontroller…I also put a berg connector on the top,so that I could debug the signals. Following scope traces show the PWM changing as the accelerometer is tilted.

Tilted to one side:

Sensor on level surface:

Tilted to the other side:

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