SPI Register Description : Arduino / ATmega328p

Intoduction

This section discusses the Atmega328p specification and features available in the chip. There are other articles in this series that discuss each features in details.

Specification

• High Performance, Low Power Atmel®AVR® 8-Bit Microcontroller Family
• Advanced RISC Architecture
  • 131 Powerful Instructions – Most Single Clock Cycle Execution
  • 32 x 8 General Purpose Working Registers
  • Fully Static Operation
  • Up to 20 MIPS Throughput at 20MHz
  • On-chip 2-cycle Multiplier
• High Endurance Non-volatile Memory Segments
  • 4/8/16/32KBytes of In-System Self-Programmable Flash Program Memory
  • 256/512/512/1KBytes EEPROM
  • 512/1K/1K/2KBytes Internal SRAM
  • Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
  • Data retention: 20 years at 85C/100 years at 25C
  • Optional Boot Code Section with Independent Lock Bits
    • In-System Programming by On-chip Boot Program
    • True Read-While-Write Operation
  • Programming Lock for Software Security
• Atmel® QTouch® library support
  • Capacitive touch buttons, sliders and wheels
  • QTouch and QMatrix® acquisition
  • Up to 64 sense channels
• Peripheral Features
  • Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode
  • One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode
  • Real-Time Counter with Separate Oscillator
  • Six PWM Channels
  • 8-channel 10-bit ADC in TQFP and QFN/MLF package with Temperature Measurement
  • 6-channel 10-bit ADC in PDIP Package with Temperature Measurement
  • Programmable Serial USART
  • Master/Slave SPI Serial Interface
  • Byte-oriented 2-wire Serial Interface (Philips I2C compatible)
  • Programmable Watchdog Timer with Separate On-chip Oscillator
  • On-chip Analog Comparator
  • Interrupt and Wake-up on Pin Change
• Special Microcontroller Features
  • Power-on Reset and Programmable Brown-out Detection
  • Internal Calibrated Oscillator
  • External and Internal Interrupt Sources
  • Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby
• I/O and Packages
  • 23 Programmable I/O Lines
  • 28-pin PDIP, 32-lead TQFP, 28-pad QFN/MLF and 32-pad QFN/MLF
• Operating Voltage:
  • 1.8 – 5.5V
• Temperature Range:
  • -40C to 85C
• Processing Speed Grade:
  • 0 – 4MHz@1.8 – 5.5V, 0 – 10MHz@2.7 – 5.5.V, 0 – 20MHz @ 4.5 – 5.5V
• Power Consumption at 1MHz, 1.8V, 25C
  • Active Mode: 0.2mA
  • Power-down Mode: 0.1µA
  • Power-save Mode: 0.75µA (Including 32kHz RTC)

Pinout of ATmega48A/PA/88A/PA/168A/PA/ Atmega328P / Atmega328

Internal Block Diagram of Atmega328P