AVR Architecture Three timers Very flexible Choose clock rate Choose “roll-over” value Generate interrupts Generate PWM signals (represent 8-bit value with using a clock signal) More in next lecture… Hence in this tutorial we will look at AVR architecture in general however all the specifics would point to Atmega32. The board is fitted with DIP sockets for all AVRs available in DIP packages.Additionally, some chip-specific differences affect code generation. AVR Architecture •RISC Harvard Architecture RISC vs. CISC Harvard vs. 2503Q–AVR–02/11 ATmega32(L) AVR CPU Core Introduction This section discusses the Atmel®AVR® core architecture in general. It can only be accessed the same way an external peripheral device is, using special pointer registers and read/write instructions, which makes EEPROM access much slower than other internal RAM.AVRs have been used in various automotive applications such as security, safety, powertrain and entertainment systems. Fig below shows the architecture of the MegaAVR series of controllers.
For more info about the features of any AVR MCU, refer to the datasheet freely distributed by the manufacturer. Von Neumann Separate program and data memory bus On-chip program memory Flash memory On-chip data memory RAM and EEPROM •32 x 8 general purpose registers •Internal and external interrupt sources •On-chip RC clock oscillator Both the USB and serial links use a variant of the STK500 protocol.USB-based AVRs have been used in the Microsoft Xbox hand controllers. Beispielsweise betrifft das den I/O-Adressraum von 8080 und infolgedessen x86, der physikalisch den normalen Datenbus verwendet. The compiled COFF object files can be C source level debugged, with variable watching, using the Atmel AVR Studio debugger. This prescaler can be reconfigured by software during run-time, allowing the clock speed to be optimized.The signal routing board sits between the base board and the target board, and routes the signals to the proper pin on the device board. Introduction to AVR Atmel AVR Microcontroller CSE466-Page 2 AVR Key Features • High Performance 8-Bit MCU • RISC Architecture – 32 Registers – 2-Address Instructions – Single Cycle Execution • Low Power • Large linear address spaces • Efficient C Language Code Density • On-chip in-system programmable memories
Code pointers (including return addresses on the stack) are two bytes long on chips with up to 128 KB of flash memory, but three bytes long on larger chips; not all chips have hardware multipliers; chips with over 8 KB of flash have branch and call instructions with longer ranges; and so forth.Note that erase and write can be performed separately in many cases, byte-by-byte, which may also help prolong life when bits only need to be set to all 1s (erase) or selectively cleared to 0s (write).aWire is a new one-wire debug interface available on the new UC3L AVR32 devices.The Unified Program and Debug Interface (UPDI) is a one-wire interface for external programming and on-chip debugging of newer ATtiny and ATmega devices.The JTAGICE mkII connects using USB, but there is an alternate connection via a serial port, which requires using a separate power supply. The hex file is then passed to the microcontroller using the AVR dude program.The power-down saves the register contents but freezes the oscillator. The first 96 locations address the Register file and I/O memory, and the internal data SRAM is addressed by the next 2048 locations. It also supports external oscillator with maximum frequency of 16MHz.ATmega32 is a powerful microcontroller because of its in system self programmable flash on a monolithic chip, provides a high flexible and cost effective solution to many embedded control applications.It also contains a 6 channel ADC out of which 4 have 10 bit accuracy and 2 have 8 bit accuracy.All I/Os and peripherals are placed in the I/O space. All the other AVR I/O ports require more compact 1.27 mm headers.Since the number of writes to EEPROM is limited – Atmel specifies 100,000 write cycles in their datasheets – a well designed EEPROM write routine should compare the contents of an EEPROM address with desired contents and only perform an actual write if the contents need to be changed.STK500 Expansion Modules:Several expansion modules are available for the STK500 board:Even though there are separate addressing schemes and optimized opcodes for accessing the register file and the first 64 I/O registers, all can also be addressed and manipulated as if they were in SRAM.There is no provision for off-chip program memory; all code executed by the AVR core must reside in the on-chip flash. Das Hauptmerkmal der Harvard-Architektur ist, dass Programm- und Datenspeicher über getrennte Busse angesteuert werden.
0856D–AVR–08/02 The Program and Data Addressing Modes The AVR Enhanced RISC microcontroller supports powerful and efficient addressing modes for access to the Program memory (Flash) and Data memory (SRAM, Register file, I/O Memory, and Extended I/O Memory). All the registers are connected directly to the ALU. Atmel ships proprietary (source code included but distribution restricted) example programs and a USB protocol stack with the device.The Atmel-ICE device or AVRISP mkII (Legacy device) connects to a computer's USB port and performs in-system programming using Atmel's software.