One of the challenges of bread boarding is finding the right voltage sources and ground pins to power and connect a variety of components. Recently I was faced with the challenge of connecting a Gumstix Overo with 1.8V TTL signals to a VectorNav VN-100T IMU with 3.3V TTL signals via SPI. I just happened to have 2 Sparkfun logic level converters on hand.
The gumstix overo is powered from a wall power supply. The vn-100t needs 3.3v power and ground. The two logic level converters each need a 3.3v power line and a 1.8v power line (high and low voltage) as well as 2 grounds each. The gumstix expansion board I’m using offers one 3.3v VCC line and two 1.8v VCC lines and 3 grounds — not even close to what I need.
So here’s what I did.
Start with some 0.1″ headers from spark fun:
These are the headers I’m talking about: sparkfun 0.1″ male headers. These come in rows of 40 pins and you can cut off the number you need. For my little project I decided I’d make a 6 pin set, two 4 pin sets, and a 3 pin set.
Solder a bare wire across the back to tie the pins together:
You can see my soldering isn’t quite professional, but as long as there is a solid connection, that’s what counts.
Hot Glue the crap out of the back to insulate the pins:
I have no idea how I ever survived before I went to Michael’s and bought a $3 hot glue gun.
Connect up your jumper wires:
I’ll probably run out of jumper wires and have to live dangerously, but I recommend connecting a wire to every pin as a safety precaution — or at least to the end pins. Murphy’s law reigns supreme when a “software guy” tries to meddle in the world of hardware. Spark fun makes some very convenient 6″ color coded jumper wires. Nice for breadboard projects.
Double check your red wires and black wires!
An VectorNav VN-100T runs $800 and an Overo is $150-200+ depending on which one. The logic level converters are $1.95 each. Guess which one fries first if you mix up your reds and blacks?