Interfacing sensors via a serial port in C

In the last section, the ZMotion IR sensor was connected to the BeagleBoard through the digital I/O interface, and successfully acquired the value of the ZMotion module into Simulink by using the GPIO Write block and the GPIO Read block. In this section, we will not only discuss how to connect a sensor based on a different interface (that is, serial communication) but also how to develop a software driver to communicate with the sensor. We will use the textual C code approach in this section, and you can migrate the code into a S-Function block for graphical programming in Simulink, which will be discussed later.

Firstly, let's get back to the datasheet of the ZMotion module. To select the Serial Interface Mode, we will need to provide a pull-up resistor (typically 100 KΩ) from TXD/SNS to VDD during the power ON process. If the device detects the voltage on that pin is greater than 2.5V in the power ON process, the device will enable the serial mode...