Easy and Affordable Digital Signal Processing The aim of this book is to teach the basic principles of Digital Signal Processing (DSP) and to introduce it from a practical point of view using the bare minimum of mathematics. Only the basic level of discrete-time systems theory is given, sufficient to implement DSP applications in real time. The practical implementations are described in real time using the highly popular ESP32 DevKitC microcontroller development board. With the low cost and extremely popular ESP32 microcontroller, you should be able to design elementary DSP projects with sampling frequencies within the audio range. All programming is done using the popular Arduino IDE in conjunction with the C language compiler. After laying a solid foundation of DSP theory and pertinent discussions on the main DSP software tools on the market, the book presents the following audio-based sound and DSP projects: Using an I²S-based digital microphone to capture audio sound Using an I²S-based class-D audio amplifier and speaker Playing MP3 music stored on an SD card through an I²S-based amplifier and speaker Playing MP3 music files stored in ESP32 flash memory through an I²S-based amplifier and speaker Mono and stereo Internet radio with I²S-based amplifiers and speakers Text-to-speech output with an I²S-based amplifier and speaker Using the volume control in I²S-based amplifier and speaker systems A speaking event counter with an I²S-based amplifier and speaker An adjustable sinewave generator with I²S-based amplifier and speaker Using the Pmod I²S2 24-bit fast ADC/DAC module Digital low-pass and band-pass real-time FIR filter design with external and internal A/D and D/A conversion Digital low-pass and band-pass real-time IIR filter design with external and internal A/D and D/A conversion Fast Fourier Transforms (FFT)

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Practical Multitasking Fundamentals Programming embedded systems is difficult because of resource constraints and limited debugging facilities. Why develop your own Real-Time Operating System (RTOS) as well as your application when the proven FreeRTOS software is freely available? Why not start with a validated foundation? Every software developer knows that you must divide a difficult problem into smaller ones to conquer it. Using separate preemptive tasks and FreeRTOS communication mechanisms, a clean separation of functions is achieved within the entire application. This results in safe and maintainable designs. Practicing engineers and students alike can use this book and the ESP32 Arduino environment to wade into FreeRTOS concepts at a comfortable pace. The well-organized text enables you to master each concept before starting the next chapter. Practical breadboard experiments and schematics are included to bring the lessons home. Experience is the best teacher. Each chapter includes exercises to test your knowledge. The coverage of the FreeRTOS Application Programming Interface (API) is complete for the ESP32 Arduino environment. You can apply what you learn to other FreeRTOS environments, including Espressif’s ESP-IDF. The source code is available from GitHub. All of these resources put you in the driver’s seat when it is time to develop your next uber-cool ESP32 project. What you will learn: How preemptive scheduling works within FreeRTOS The Arduino startup “loopTask” Message queues FreeRTOS timers and the IDLE task The semaphore, mutex, and their differences The mailbox and its application Real-time task priorities and its effect Interrupt interaction and use with FreeRTOS Queue sets Notifying tasks with events Event groups Critical sections Task local storage The gatekeeper task

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