PCA9306 Level Shifter

Persistent nagging problem — shifting logic levels between devices that are fabbed with different technologies so their voltages end up being different. Digital circuits “trigger” based on voltage levels — a logic 1 or high signal is relative to the electrical specifications of the device and the fabrication process of the silicon. (A techie diagram is available here.) It’s not a new problem, but one I seem to be coming across more and more as I use the Arduino to do quick sketches of project ideas, or to stand-in for a more embedded solution that might use another of the Atmel 8-bit devices later on when the design and details are more refined.

I’ve tried a bunch of things, including the kind of canonical reference circuit from Philips that uses the BSN20 MOSFET. Sparkfun has a neat little breakout board using a MOSFET, the BSS138. Same principle, built out for you by the fine folk at Sparkfun.

While poking around some more what cause of this PSX project where I have an Arduino trying to talk to a Parallax Propeller, I found reference to a single-chip solution from TI that’s called a PCA9306, which is that small guy up in the photos above. (Just a hair smaller than an 8-pin SSOP package, which means that it was too small to fit on this SSOP break-out — the pins don’t reach the copper, so I had Igor do some hand work to get that to take hold.
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Propeller and Arduino

Not the most exciting thing, but an interesting challenge here. I’m trying to get a Parallax Propeller chip to behave nicely as an TWI/I2C slave with the idea that I’d like to create a pretty much black-box interface that’ll allow a TWI/I2C master to control it for stuff. Ultimately I’d like to use the Propeller in the PSX project. It’ll sit in between a Playstation 2 and a normal Playstation controller, and be available as a TWI/I2C slave, so that another device, that doesn’t really care to figure out how to talk to a Playstation 2 or its controllers can make the PSX box with the Propeller in it emulate, for the Playstation, certain button presses, etc. Or, it could “read” over TWI/I2C from the PSX box and find out what the real controller is doing. Or, it could just read or write from a special TWI register address to make the PSX box (with the Propeller in it) just do a “pass-thru” so that the signals just go straight through as if there were nothing in between.

That’s the theory. In practice, setting up this test jig took more time that I would’ve thought.
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