ATMEGA328-AU

The ATMEGA328-AU from Microchip Technology (formerly Atmel) is an 8-bit AVR RISC-based microcontroller from the megaAVR family, offering 32 KB of In-System Programmable Flash with Read-While-Write capabilities, 2 KB of SRAM, and 1 KB of EEPROM. The device achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and processing speed with up to 20 MIPS at 20 MHz. It features 23 programmable I/O lines, 32 general-purpose working registers, three flexible timer/counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented Two-Wire serial interface (I2C), an SPI serial port, and a 6-channel 10-bit A/D converter. The device operates between 1.8 V and 5.5 V. Note: This device is now classified as Not Recommended for New Designs (NRND); the ATMEGA328PB is the recommended upgrade path.

The ATMEGA328-AU uses a modified Harvard architecture with separate program and data memory spaces connected by dedicated buses. The AVR CPU core features 32 general-purpose 8-bit registers (R0-R31), all directly connected to the Arithmetic Logic Unit (ALU), enabling single-cycle execution of most instructions. Registers R26-R31 serve as 16-bit pointer pairs (X, Y, Z) for indirect addressing. The two-stage pipeline (fetch and execute) enables 1 MIPS per MHz throughput. The Flash memory stores the program and can be reprogrammed in-system via SPI. The 2 KB SRAM provides fast data access, while the 1 KB EEPROM offers non-volatile data storage that survives power cycles. Power management includes five modes: Idle (CPU stopped, peripherals running), ADC Noise Reduction (CPU stopped, ADC active), Power-save (timer running), Power-down (everything stopped except watchdog), and Standby (oscillator running but not driving CPU). Brown-out detection with configurable thresholds prevents erratic operation during voltage dips.

• Arduino ecosystem: Core MCU for Arduino Uno boards, enabling rapid prototyping and education in embedded systems
• Sensor nodes: Data acquisition from environmental sensors with low-power sleep modes for battery operation
• Motor control: BLDC and stepper motor control using 6-channel PWM and timer capture/compare
• Consumer appliances: Simple control logic in home appliances, white goods, and personal care devices
• LED lighting: PWM-based dimming and color mixing controllers for architectural and decorative lighting