Module 17: Digital Electronics
Almost every piece of modern electronics is digital at its core. A microcontroller reads a sensor through an analog-to-digital converter, decides what to do with logic and arithmetic, and drives the outside world through digital outputs, PWM and digital-to-analog converters. Phones, audio interfaces and test instruments digitize signals and process them with mathematics instead of coils and capacitors. To understand, build or repair any of this equipment, you need to understand how digital circuits represent and process information — and how signals cross between the analog and digital worlds.
- Convert between binary, hexadecimal and decimal, and use two's complement for negative numbers
- Describe the seven basic logic gates and design simple logic from a truth table
- Explain how latches, flip-flops, counters and shift registers store and move data
- Explain how ADCs and DACs work and choose a converter for a job
- Apply the Nyquist criterion and prevent aliasing
- Describe what digital signal processing does, and compare FIR and IIR filters
- Use the FFT to analyze signals and interpret an FFT or waterfall display
Module Overview
The module starts with the language of digital electronics: binary and hexadecimal numbers. It then builds up the hardware, from logic gates and truth tables to latches and flip-flops that store information, and the counters and shift registers built from them — the circuits behind every timer, frequency divider and serial interface.
The middle of the module crosses the boundary between analog and digital. Analog-to-digital and digital-to-analog converters are the interfaces between real-world signals and processors, and the sampling theorem sets the rules for converting faithfully without aliasing.
The final lessons cover digital signal processing: what a DSP chain does, how FIR and IIR filters work and when to use each, and how the Fast Fourier Transform turns a block of samples into a spectrum — the technique behind oscilloscope FFT functions, sound-card analyzers, waterfall displays and OFDM communications.
Lessons
Binary and Number Systems
Binary and Number Systems
Binary counting, conversion to and from decimal, binary arithmetic, two's complement, and binary in everyday electronics.
Hexadecimal
Hexadecimal
Hex notation, conversions, and where hex appears in datasheets, firmware files and bus captures.
Logic Gates
Logic Gates
NOT, AND, OR, NAND, NOR, XOR and XNOR, universal gates, De Morgan's theorems, and CMOS and TTL logic families.
Truth Tables
Truth Tables
Building truth tables, sum-of-products and product-of-sums, don't-care conditions, and designing logic from a table.
Flip-Flops and Latches
Flip-Flops and Latches
SR latches, D, JK and T flip-flops, edge triggering, setup and hold times, metastability and synchronizers.
Counters and Shift Registers
Counters and Shift Registers
Ripple and synchronous counters, modulo counters, frequency division, and SIPO, PISO and other shift registers.
Analog to Digital Conversion
Analog to Digital Conversion
Resolution and quantization, SAR, flash and delta-sigma ADCs, reference voltage, oversampling, and choosing an ADC.
Digital to Analog Conversion
Digital to Analog Conversion
Binary-weighted and R-2R DACs, resolution, settling time, glitches, reconstruction filtering and PWM as a DAC.
Sampling Theory and Nyquist
Sampling Theory and Nyquist
The Nyquist rate, aliasing and anti-aliasing filters, bandpass sampling, and sampling in real systems.
DSP Basics
DSP Basics
The DSP chain, convolution, multiply-accumulate hardware, decimation and interpolation, and DSP applications.
FIR and IIR Filters
FIR and IIR Filters
FIR and IIR structures, linear phase, stability, windowing, poles and zeros, and choosing a filter type.
The Fast Fourier Transform
The Fast Fourier Transform
From DFT to FFT, bins and resolution, leakage and windowing, waterfalls, and OFDM.