Electronics Introduction

  In home control systems (smart home, automation, etc.), the microprocessors used are typically low-power, embedded processors that balance performance, cost, and connectivity . These fall into the categories of microcontrollers (MCUs) and System-on-Chip ( SoC ) processors .  Common Types of Microprocessors Used in Home Control:  1. Microcontrollers (MCUs) Used for simple control tasks like lighting, HVAC, door locks, and sensors. ▶ Popular Families: ESP32 / ESP8266 (by Espressif) Built-in Wi-Fi and Bluetooth Ideal for IoT and wireless home devices STM32 (by STMicroelectronics ) High-performance ARM Cortex-M Used in smart appliances and automation ATmega328P (used in Arduino Uno ) Good for hobby and basic automation tasks PIC microcontrollers ( Microchip ) Widely used in consumer electronics  2. System-on-Chip (SoC) Processors Used in smart hubs, gateways, voice assistants, and media devices. ▶ Examples: ...

 Optimizing memory usage in an Arduino sketch is crucial, especially on devices with limited SRAM (e.g. only 2 KB on the ATmega328P ). Here's a guide on how to do it effectively: 1. Understand Arduino Memory Types Memory Use Flash Program code & constants ( PROGMEM ) SRAM Variables, arrays, stack/heap EEPROM Non-volatile data storage (optional) 2. Reduce SRAM Usage (Key Focus Area) Use F() Macro Store string literals in Flash instead of SRAM : cpp Serial. print ( F ( "This is stored in Flash" )); Use PROGMEM for Constant Data Store arrays, strings, or lookup tables in program memory: cpp const char msg[] PROGMEM = "Hello" ; Access with: cpp char buffer[ 6 ]; strcpy_P (buffer, msg); Minimize Global Variables Global variables are allocated in SRAM. Reduce usage or convert to const + PROGMEM where possible. 3. Use Smaller Data Types Replace int (16-bit) with byte or uint8_t (8-bit) where possible. Use float only when necessar...

 The ATmega328P microcontroller has one UART (Universal Asynchronous Receiver-Transmitter) , also referred to as a USART (Universal Synchronous and Asynchronous Receiver-Transmitter). Key Features of the ATmega328P UART: Asynchronous Communication : Supports standard UART communication. Used for serial communication protocols such as RS-232. Synchronous Communication : Can operate in synchronous mode, where a clock signal is shared between the transmitter and receiver. Baud Rate : Programmable baud rate. Common baud rates (e.g., 9600, 115200) are supported. Applications : Widely used in Arduino Uno for serial communication with computers or other devices. Communicates through pins TXD (Transmit Data) and RXD (Receive Data) . TX (Transmit) : Pin 3 (PD1) RX (Receive) : Pin 2 (PD0) For applications requiring additional UARTs, you can use external multiplexers or software-based UART implementations (SoftSerial libraries in Arduino ).