You can use a 74LS04 hex inverter chip to perform the 3.3v to 5v level shift, although it is not required
Here is how to wire things so the 3.3v goes in, it comes out inverter (off when it should be on), goes in again and then comes out how we want at 5v
Going from 5v down to 3.3v is important to protect the phone. Thankfully it is very easy with two resistors.
This is how to wire the resistors to bring down the voltage from the Arduino before it goes into your phone. Other resistor combinations work so long as the math works out and you get something close to 3.3v. Precision is not required here.
Sparkfun also sells a nice level shifter that makes things even easier and gives you peace of mind that the voltage is correct.
The chip and breakout board do not come with these pins so we recommend buying some and soldering them on.
Using a breadboard is one easy way to solder the pins and ensure they are straight. The breadboard sucks away heat so it can be tought to get the parts the right temperature though.
Here is the Sparkfun logic level conveerter wired into the Truckbot's breadboard. Note that it requires two power sources.
A wide shot shows we have a lot of space now for add-on sensors.
We're testing out a 3.7v LiPo battery to power the batteries and it also serves as our low power input for the Sparkfun converter.
All wired up with a new range sensor onboard as well.
