Power Pins:

• Vin - this is the power pin. Since the ATSAMD09 uses 3.3V, we have included an on-board voltage regulator that will take 3-5VDC and safely convert it down. You can power from 3.3V to 5V
• 3Vo - this is the 3.3V output from the voltage regulator, you can grab up to 100mA from this if you like
• GND - common ground for power and logic

Logic Pins:

• 23 / SCL - this is the I2C clock pin, connect to your microcontrollers I2C clock line. There is a 10K pullup on this pin to 3.3V. I2C is 'open drain' which means as long as you don't add an extra pullup you can use with 5V logic devices.
• 22 / SDA - this is the I2C data pin, connect to your microcontrollers I2C data line. There is a 10K pullup on this pin to 3.3V. I2C is 'open drain' which means as long as you don't add an extra pullup you can use with 5V logic devices.
• RST - this is the reset pin. Pulling this pin to ground resets the device.

GPIO Pins:

• Pins 9, 10, 11, 14, 15, 24, and 25 can be used as GPIO.

Neopixel Pins:

• Pins 9, 10, 11, 14, 15, 24, and 25 can be used as the NeoPixel output.

Address Pins:

• 16 / AD0 - this is the ADDR0 pin. Connect this to ground to increment the devices I2C address by 1.
• 17 / AD1 - this is the ADDR1 pin. Connect this to ground to increment the devices I2C addres by 2.

ADC Pins:

• 2 - this pin can be configured as an ADC input.
• 3 - this pin can be configured as an ADC input.
• 4 - this pin can be configured as an ADC input.

PWM Pins:

• 5 - this pin can be configured as a PWM output.
• 6 - this pin can be configured as a PWM output.
• 7 - this pin can be configured as a PWM output.

Interrupt Pins:

• 8 / IRQ - this pin gets pulled low by the seesaw to signal to your host microcontroller that an interrupt has occurred.

Programming Pins:

• SWD - this pin connects to SWDIO of an SWD compatible programmer to program the device over SWD.
• SWC - this pin connects to SWCLK of an SWD compatible programmer to program the device over SWD.
• RST - this pin connects to RESET of an SWD compatible programmer to program the device over SWD.