multiplexing hardware

TCA9548A and a dime. Yes, I have
to solder that to a circuit board.

So... I got this chip in the mail from Texas Instruments the other day (if you ask nice, they will ship you free samples...). Looks cool, but it's not even half the size of a dime! How the hell am I supposed to solder each little pin coming off of this damn thing?!

The chip is the TCA9548A 8 channel I2C switch. It was recommended to me by Kerry Wong on his blog article about multiplexing I2C chips. The point of the chip is to be able to connect 4 of my ADXL345 accelerometers to the single I2C input line on the arduino. Now the whole point of I2C is to be able to connect multiple sensors to a single set of input lines; but, to do this, the sensors all need a unique hardware address. My accelerometers all have the same address, so I have to put the TCA9548A in between my I2C input lines and my accelerometers. The TCA9548A allows you to select one pair of input lines as the line to listen to (one out of the 8 supported that is).

28 pin 0.65 pitch TSSOP compatible
prototype board from Schmart Board

I made a quick trip to the local electronics shop and to Radio Shack and all the prototype circuit boards I could find looked like a rhinoceros compared to my little ant of a chip. A little ol' googling of the interwebs led me to SchmartBoard, a little company up in San Ramon that makes prototyping circuit boards that noobs like myself can use to deal with chips this small (That's a Thin-Shrink Small Outline Package or TSSOP for those in the know). And it turns out I was cruising the motorcycle right by their shop on business the next day! So, I stopped in and met up with Neal Greenberg, the VP of sales and marketing. Neal was fantastic and gave me the run down on what I needed to do and hooked me up with this little SOIC prototype board that will fit my TSSOP integrated circuit perfectly.

My next battle is that I've gotta find a soldering iron conical tip with a point that's smaller than 0.65 mm...