Adafruit ADA3657 Adafruit ATSAMD09 Breakout with seesaw

Adafruit seesaw is a near-universal converter framework which allows you to add and extend hardware support to any I2C-capable microcontroller or microcomputer. Instead of getting separate I2C GPIO expanders, ADCs, PWM drivers, etc, seesaw can be configured to give a wide range of capabilities. For example, Adafruits ATSAMD09 breakout with seesaw gives you3 x 12-bit ADC inputs 3 x 8-bit PWM outputs 7 x GPIO with selectable pullup or pulldown1 x NeoPixel output (up to 63 pixels)1 x EEPROM with 64 byte of NVM memory (handy for storing small access tokens or MAC addresses)1 x Interrupt output that can be triggered by any of the accessories2 x I2C address selection pins1 x Activity LED But you can reprogram and reconfigure the chip to have more or less of each peripheral - as long as it fits into the ATSAMD09D14's firmware.There is a UART converter but it isn't included in the default firmware.