You can tile up to 32 NeoTrellis PCBs on a single 2-wire I2C bus. This allows you to easily build up to 16x16 larger panels which can be lots of fun!
To start with, its a good idea to assemble and test each individually so you know each NeoTrellis works individually.
There's little nubs on the sides of some PCBs that keep them on the assembly panel, you can file them off with any file or sandpaper.
Arrange the tiles up the way you want, we'll start with two. Make sure the Adafruit logo is lined up the same.
Solder two blobs of solder on two adjacent finger pads.
A small wire (or a few strands of wire) might help make the bridge. Just be sure the bridge doesn't touch any of the adjacent pads.
Use your soldering iron to drag solder from one pad to another, with a little effort they'll stick together and make a connection. You can add more solder to make the connection stronger. Its still not mechanically strong - so be careful not to bend or shake the arrangement
Addressing
Each NeoTrellis tile must have a unique address. You can set the addresses on the back of each panel using a little solder over the address jumpers.
The seesaw driver chip on the Trellis has a default I2C address of 0x2E. Since each device on an I2C bus must have a unique address, its important to avoid collisions or you'll get a lot of strange responses from your electronic devices!
Luckily, the seesaw has 5 address adjust pins, so that the address can be changed. Each pin changes one binary bit of the address, so you can set the address to any hex number between 0x2E and 0x4E inclusive
The panels don't have to have consecutive address #'s, they just have to be unique.
Changing Addresses
You can change the address of very easily. Look on the back to find the three A0, A1, A2, A3 and A4 solder jumpers.
Each one of these is used to hard-code in the address. If a jumper is shorted with solder, that sets the address.
- A0 sets the lowest bit with a value of 1
- A1 sets the bit with a value of 2
- A2 sets the bit with a value of 4
- A3 sets the bit with a value of 8
- A4 sets the bit with a value of 16
The final address is 0x2E + A4 + A3 + A2 + A1 + A0. So for example if A2 is shorted and A0 is shorted, the address is 0x2E + 4 + 1 = 0x33
Address Cheat Sheet
If you take on a project using many NeoTrellis boards, here's a handy cheat sheet for address/jumper value combos:
(default) 0x2E A0 (+1) 0x2F A1 (+2) 0x30 A2 (+4) 0x32 A3 (+8) 0x36 A4 (+16) 0x3E A0+A1 (+3) 0x31 A0+A2 (+5) 0x33 A0+A3 (+9) 0x37 A0+A4 (+17) 0x3F A0+A1+A2 (+7) 0x35 A0+A1+A3 (+11) 0x39 A0+A1+A4 (+19) 0x41 A0+A1+A2+A3 (+15) 0x3d A0+A1+A2+A4 (+23) 0x45 A0+A1+A3+A4 (+27) 0x49 A0+A1+A2+A3+A4 (+31) 0x4d A0+A2+A3 (+13) 0x3B A0+A2+A3+A4 (+29) 0x4b A0+A2+A4 (+21) 0x43 A0+A3+A4 (+25) 0x47 A1+A2 (+6) 0x34 A1+A3 (+10) 0x38 A1+A4 (+18) 0x40 A1+A2+A3 (+14) 0x3c A1+A2+A3+A4 (+30) 0x4c A1+A3+A4 (+26) 0x48 A2+A3 (+12) 0x3a A2+A4 (+20) 0x42 A2+A3+A4 (+28) 0x4a A3+A4 (+24) 0x46
Thanks to Okyeron on the Lines forum for creating this list.
Here's an example of address jumper settings for an 8x8 grid from Okyeron:
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