The default I2C address is 0x49.

Power Pins

• VIN - This is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 3V microcontroller like a Feather RP2040, use 3V, or for a 5V microcontroller like Arduino, use 5V.
  
• - (GND) - This is common ground for power and logic.

I2C Logic Pins

The default I2C address is 0x49.

• C - I2C clock pin (SCL), connect to your microcontroller I2C clock line. There's a 10K pullup on this pin.
• D - I2C data pin (SDA), connect to your microcontroller I2C data line. There's a 10K pullup on this pin.
• STEMMA QT - These connectors allow you to connect to development boards with STEMMA QT / Qwiic connectors or to other things with various associated accessories.

Address Jumpers

On the back of the board are three address jumpers, labeled A0, A1, and A2, above the breakout pads along the bottom of the board. These jumpers allow you to chain up to 8 of these boards on the same pair of I2C clock and data pins. To do so, you cut the jumpers "open" by separating the two pads.

If you happen to need more than 8, it's possible to set the I2C address with a special address-change command that is saved to the onboard non-volatile EEPROM memory.

The default I2C address is 0x49. The other address options can be calculated by "adding" the A0/A1/A2 to the base of 0x49.

A0 sets the lowest bit with a value of 1, A1 sets the next bit with a value of 2 and A2 sets the next bit with a value of 4. The final address is 0x49 + A2 + A1 + A0 which would be 0x50.


If only A0 is cut, the address is 0x49 + 1 = 0x4A


If only A1 is cut, the address is 0x49 + 2 = 0x4B


If only A2 is cut, the address is 0x49 + 4 = 0x4D

The table below shows all possible addresses, and whether the pin(s) should be Low (left closed) or High (cut open).

Interrupt Pin and LED

• INT - This is the interrupt output pin. It can be configured to pulse low whenever rotation or push-buttoning is detected so you do not have to spam-read the I2C port to detect motion.
• Interrupt LED - On the back of the board to the left of the bottom row of breakout pins is the interrupt LED. It is the red LED and turns on whenever an interrupt is detected.

UPDI Pin

The UPDI pin is not labeled on the board silk and is located next to the interrupt (INT) pin.

• UPDI - This is the single-pin Unified Program and Debug Interface. This pin is for external programming or on-chip-debugging for the ATtiny817 running the seesaw firmware. We have a page in the ATtiny Breakouts with seesaw Learn Guide detailing how to reprogram these chips with your own firmware (at your own risk). We don't provide any support for custom builds of seesaw - we think this is cool and useful for the Maker community.

Power LED

• Power LED - On the back of the board, below the STEMMA connector on the right, is the power LED, labeled on. It is the green LED.

Rotary Encoder Pins

On the front of the board are outlines for four rotary encoders on the board silk. They are labeled #0 to #3. This lets you know where you should place the rotary encoders for soldering. This breakout does not come with any encoders soldered on. We sell a common 24-detent-with-switch encoder here and it works wonderfully. 

Each of the four encoder sections has pins for reading the encoder and a switch. The encoder pins are the three pins on the right side of the encoder outline. The encoder A pin is towards the bottom of the board and the encoder B pin is towards the top of the board. The center pin is ground.

The switch pins are the two pins on the left side of the encoder outline. The switch pin is towards the bottom of the board and the pin towards the top of the board is ground. The two larger oval pins are both connected to ground.

These are the pin names in the seesaw firmware for each rotary encoder:

• Encoder #0
  • Switch: pin 12
  • Encoder A: pin 8
  • Encoder B: pin 9
• Encoder #1
  • Switch: pin 14
  • Encoder A: pin 10
  • Encoder B: pin 11
• Encoder #2
  • Switch: pin 17
  • Encoder A: pin 2
  • Encoder B: pin 3
• Encoder #3
  • Switch: pin 9
  • Encoder A: pin 4
  • Encoder B: pin 5