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 0x50.

• SCL - I2C clock pin, connect to your microcontroller I2C clock line. There's a 10K pullup on this pin.
• SDA - I2C data pin, connect to your microcontroller I2C data line. There's a 10K pullup on this pin.

STEMMA QT Connector

The default I2C address is 0x50.

• STEMMA QT connector - This connector is located on the front of the board, at the top in the center. It allows you to connect to development boards with STEMMA QT / Qwiic connectors or to other things with various associated accessories.

Buttons

There are two small buttons towards the center of the board, and four large buttons arranged in a diamond on the right side of the board.

• Start - This is a small button, located to the left of center. It is pin 16 in the seesaw firmware.
• Select - This is a small button, located to the right of center. It is pin 0 in the seesaw firmware.
• A - This is a large button, located to the right in the diamond. It is pin 5 in the seesaw firmware.
• B - This is a large button, located at the bottom of the diamond. It is pin 1 in the seesaw firmware.
• X - This is a large button, located at the top of the diamond. It is pin 6 in the seesaw firmware.
• Y - This is a large button, located to the left in the diamond. It is pin 2 in the seesaw firmware.

Joystick

This is the 2-axis joystick located on the left side of the board.

• X-axis - The joystick x-axis (horizontal) is on pin 14 in the seesaw firmware.
• Y-axis - The joystick y-axis (vertical) is on pin 15 in the seesaw firmware.

Power LED

• Power LED - On the front of the board, to the right of the STEMMA connector, is the power LED. It is the green LED.

Interrupt Pin and LED

• IRQ - This is the optional interrupt pin. It is pin 5 in the seesaw firmware. This pin will let you know when a button on the gamepad has been pressed. You can use it to alert the Feather to the button press or release, to free up processor time for other tasks. Since its optional you will need to connect a separate wire for the IRQ line, or simply leave it disconnected.
• IRQ LED - On the front of the board, to the left of the STEMMA connector, is the IRQ LED. It is the red LED. It turns on whenever the interrupt is detected.

Address Jumpers

On the back of the board are two address jumpers, labeled A0 and A1, on the back of the board above the "w" in the "seesaw" label. These jumpers allow you to chain up to 4 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 4 addresses, 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 0x50. The other address options can be calculated by "adding" the A0/A1 to the base of 0x50.

A0 sets the lowest bit with a value of 1 and A1 sets the next bit with a value of 2. The final address is 0x50 + A0 + A1 which would be 0x53.


If only A0 is cut, the address is 0x50 + 1 = 0x51.


If only A1 is cut, the address is 0x50 + 2 = 0x52.

If both A0 and A1 are cut, the address is 0x50 + 1 + 2 = 0x53.

UPDI Pin

• UPDI - This is the single-pin Unified Program and Debug Interface. This pin is for external programming or on-chip-debugging for the ATtiny816 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.