The Serial Wombat Xiao Module 18AB Coprocessor board (PCB0023) is the perfect complement to your Seeeduino Xiao or equivalent module.
The Xiao does high level processing, wireless or USB communication, and display driving, while the Serial Wombat 18AB chip’s built in firmware handles hard time embedded systems tasks like A/D conversion, rotary encoder reading, PWM generation, button debouncing, Servo control, PID and other control loops, and much more. 18 I/O pins are available. For a full list of available pin modes, see the classes available through the libraries.

PCB0023 provides an I2C connection between the Xiao module and the Serial Wombat chip. The Serial Wombat chip responds to address 0x6B by default, but can be changed with the addition of a resistor. Available Arduino, Python / MicroPython, and C# libraries allow easy access to the Serial Wombat chip’s extensive functionality. QWIIC/Stemma connectors and additional pins on the I2C bus allow easy addition of additional I2C devices.

PCB0023 expects to be powered by the 5V line from the Xiao module. PCB0023 has a built in 250mA linear regulator that provides 3.3V to the Serial Wombat Chip and QWIIC connectors from the 5V input. Optionally, 3.3V can be provided to the board directly, with the option to bridge the PCB’s 3.3V power supply to the Xiao’s 3.3V