Good thing about Arduino form factor is there are a few Arduino shields for expanding serial communication and analog and digital pins just with wires. The base shield has breakout pins for I2C, Analog, Digital, and UART. There is a reset switch and switch between 3.3V and 5V IO voltage.
The Grove Arduino Base Shield pins can break out the Arduino IO pins in the table below. With their 4-pin cables, we can connect to other sensor modules easily 🙂
Note that Arduino Uno has only one dedicated UART. So no Serial1 supported.
Now, with pins coming out the base shield, the three boards (base shield –> DC Motor Shield –> XMC4700 Relax kit) can be stacked together.
Here is the top down view with I2C based sensors.