16x2 LCD Pi Plate schematic

[sportsnapper]

Hi,

I've downloaded and looked at the schematic that goes with this plate. Can't find one in the UK at the mo, but I have all the bits so I'll breadboard it for the moment. But I can't work out what the three symbols on the left of the schematic are - they're all bunched up and the text is overwritten.

Any ideas - do I need these???

Gareth

[adafruit_support_mike]

Those are HIGH/LOW connections for the MSP23017's address pins. In the schematic, they're all wired low, giving the device an address of 0.. well, technically '40' since the chip's built-in address is 40 and the value defined by the address pins gets added to that.

Every I2C device has a 7-bit address. The four highest bits are generally set by the chip manufacturer, but you can set the remaining three by wiring the chip's address pins high or low. That allows you to put up to 8 of the same device, and up to 16 different kinds of devices, on the same bus.

If you're building your own version of the circuit, just wire those pins to GND.

[sportsnapper]

OK, I understand. I'm using a Quick2wire msp23017 expansion board, and that addressing is built into their board via a dip switch - so I don't really need to worry.

Thanks for getting back to me so quickly...