Interface GPIO using CMOS 4066 quad switch

[mike_p]

I have a few 4066 chips lying around and was wandering if anyone has considered using them as a cheap/simple method of level shifting when interfacing the Pi GPIO pins to external devices?

[Burngate]

4066.jpg (10.88 KiB) Viewed 749 times

It's quite amazing what you can do with bilateral switches.
Power it from 5v, attach one side to 3v3 and the other through a pull-down resistor to ground, and you've got a buffer or level translator - the control is at 5v, the output at 3v3.
Attach one side to ground and a pull-up resistor to 3v3 on the other, and you've got an inverter.
Parallel two of them, you've got a NOR gate. From there, you can do almost anything (you'd need quite a few to build an ARM processor, and it would be rather slow)