Summary

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.
• C multidimensional arrays are arrays of arrays.