16x2 LCD display i2c - More than one?

[pprovost]

Hi all,

I just got some 16x2 display w/ shield kits. They are working nicely. I would like to daisy chain them and drive them from a single Pi. The MCP23017 controller has three address lines, so I guess I could chain up to 8 displays on the i2c bus. Is that right? Any way I can hack the PCB to set different addresses? Sure, I could put it on an external board, solder some leads to the PCB and do as I please, but I quite like the format of the display attached to the PCB.

Any advice or suggestions? Can I drive 8 16x2 displays through i2c from a single Raspberry Pi?

Thanks!

Paul

[adafruit_support_bill]

With a little address hacking, you should be able to drive 8 boards on the same I2C bus.

[pprovost]

Thanks for the answer.

So can I hack the Pi Plate to do this, or do I have to bring the MCP23017 to an outside board and do the address hacking there? I see three tabs in the back of the board. Are these the address lines?

Please advise!

Paul

Photo on 13-01-02 at 8.13 AM.jpg (57.06 KiB) Viewed 363 times

[adafruit_support_bill]

I don't have one on hand to verify, but it looks like those pads are adjacent to the address pins on the chip. I'll check further to confirm.

[adafruit]

Those are address pins and you can cut the trace on the middle pads on one side to ground and then solder the middle pads to t he other side to adjust the address. however, its not supported and we dont have any tutorials on it, just something we tossed onto the PCBs for fun

[pprovost]

Just as I thought. Thanks! Will have fun!

Can you draw me up where I have to cut the trace and where to solder?

Paul

[adafruit_support_bill]

If you look closely: for each set of three pads, the middle pad will be connected to one of the others. Cut the connecting trace, and use a drop of solder to bridge to the pad on the other side.

[pprovost]

Got it. I guess the eyes aren't what they used to be <puts glasses on>.

Thanks for your help, sonny!