This was a long chapter with lots of theory and examples about buses on BeagleBone. We learned first that a bus is an interconnection of lines with software logic for data transfer. Different sensors/devices follow different set of rules for connection called bus protocols. The BeagleBone processor has support for UART devices and I2C, SPI buses. All these are serial protocols. We learned that UART is one-to-one connection carrying out asynchronous data transfer. Then we learned about the I2C and SPI bus. We wrote programs to read/write from UART, read from the ADXl345 sensor via I2C and displayed text on the Nokia LCD via SPI. We covered major buses supported by BeagleBone. Now, we will move to writing IoT programs in Python in the next chapter.