This chapter has introduced digital communications and digital signals. The following points summarize the chapter:
The fundamental perspective introduced by information theory is that all information can be represented by binary codes. Information represented in binary is said to be digital.
Digital communication systems have three layers, each with a pair of peers:
Layer 3: Source encoding and its peer source decoding
Layer 2: Channel encoding and and its peer channel decoding
Layer 1: Modulation and its peer demodulation
Three important modes of communication are
Path, which can be serial or parallel
Timing, which can be synchronous or asynchronous
Direction, which can be simplex, half-duplex, or full-duplex
There are several communication standards and protocols that describe widely adopted hardware and operation used by most communication devices.
A universal asynchronous receivers-transmitter (UART) is a hardware device that allows a computer to asynchronously and serially communicate with peripheral devices. A UART functions as an interface between a processor's I/O bus and the pinout to which peripheral devices can be connected.
The key elements of a UART are digital logic circuits called shift registers.
The myRIO target computer can communicate with target devices over several communication channels: DIO, AIO, UART, SPI, and . All of these interface through three connectors, A, B, and C.
The myRIO C library's UART.h header file and UART.c source file define five functions for programming UART communication: Uart_Open() opens a UART session, Uart_Close() closes a session, Uart_Write() writes data to a UART session's port, Uart_Read() reads data from a UART session's port, and Uart_Clear() clears a UART session port's receive buffer.
The myRIO C library's DIO.h header file and DIO.c source file define a custom data type MyRio_Dio for configuring the DIO, a function Dio_ReadBit() for reading DI, and a function Dio_WriteBit() for writing DO.
C structures are used to group information that belongs together.