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In this section, we describe the overall architecture of the Atmel AVR ATmega16.We begin with an introduction to the concept of the reduced instruction set computer (RISC) and briefly describe the Atmel Assembly Language Instruction Set. A brief introduction is warranted because we will be programming mainly in C throughout the course of the book. We then provide a detailed description of the ATmega16 hardware architecture. Reduced Instruction Set Computer Microcontroller operation is controlled by a user-written program interacting with the fixed hardware architecture resident within the microcontroller. A specific microcontroller architecture can be categorized as accumulator-based, register-based, stack-based, or a pipeline architecture. The Atmel ATmega16 is a register-based architecture. In this type of architecture, both operands of an operation are stored in registers collocated with the central processing unit (CPU). This means that before an operation is performed, the computer loads all necessary data for the operation to its CPU. The result of the operation is also stored in a register. During program execution, the CPU interacts with the register set and minimizes slowermemory accesses.Memory accesses are typically handled as background operations. Coupled with the register-based architecture is an instruction set based on the RISC concept. A RISC processor is equipped with a complement of very simple and efficient basic operations. More complex instructions are built up from these very basic operations. This allows for efficient program operation. The Atmel ATmega16 is equipped with 131 RISC-type instructions. Most can be executed in a single clock cycle. The ATmega16 is also equipped with additional hardware to allow for the multiplication operation in two clock cycles. In many other microcontroller architectures, multiplication typically requires many more clock cycles. For additional information on the RISC architecture, the interested reader is referred to Hennessy and Patterson [3]. The Atmel ATmega16 [2] is equipped with 32 general purpose 8-bit registers that are tightly coupled to the processor’s arithmetic logic unit within the CPU. Also, the processor is designed following the HarvardArchitecture format.That is, it is equipped with separate, dedicated memories and buses for program and data information. The register-based Harvard Architecture coupled with the RISC-based instruction set allows for fast and efficient program execution and allows the processor to complete an assembly language instruction every clock cycle. Atmel indicates the ATmega16 can execute 16 million instructions per second when operating at a clock speed of 16 MHz.

In this article will discuss the use of DST-128 AVR Stamp. further discussion we need to know the specifications of the DST-128 AVR Stamp. dst avr stamp • 128 Kb Flash PEROM • 4Kb EEPROM • 4Kb SRAM • On Chip Analog Comparator • 8 Channel 10 bit ADC • 2 8 bit PWM • 6 PWM dengan resolusi programmable (2-16 bit) • Dual Programmable UART • SPI Interface • Programmable Watchdog dengan On Chip Oscillator • Adjustable VREF ADC • 53 bit I/O • Power On Reset dan Programmable Brown out detection • Internal Calibrated RC Oscillator After knowing the specifications of the DST-AVR Stamp, we will discuss The first application discussed is the use of timers. in each application, such as the indicator to indicate the program is running, as well as reference time for the application. And the most simple application is a digital clock. This application will make PORTC bit AVR ranging from 0 to bits 7 blinks every 2 ^n bit number, which blink on bit 0 is 0.5 ms. So if the second bit will be blinks every 2 ^ 2 or 4 * 0.5 mS then at the bit to two flashes every 2ms. timing can run correctly then the timer interrupt will be generated every Timer used for this application is the timer "1". • Normal Mode • Compare Mode • Fast PWM Mode • Phase Correct PWM Mode • Phase and frequency correct PWM Mode For this application the timer operates in normal mode where the timer will count ranging from 0-65535. Timer 1 prescaler which has several functions to dividing the crystal frequency where the frequency of this crystal will be used as a source of countdown timer. Piece of program to set the timer registers as follows: TCCR1A=0x00; TCCR1B=0x04; // Timer/Counter 1 initialization // Clock source: System Clock // Clock value: 46,875 kHz // Mode: Normal top=FFFFh // OC1A output: Discon. // OC1B output: Discon. // OC1C output: Discon. // Noise Canceler: Off // Input Capture on Falling Edge // Timer 1 Overflow Interrupt: On TCNT1H=0xB7; TCNT1L=0x1B; // Timer/Counter 1 initialization value ICR1H=0x00; ICR1L=0x00; OCR1AH=0x00; OCR1AL=0x00; OCR1BH=0x00; OCR1BL=0x00; OCR1CH=0x00; OCR1CL=0x00; // Input Capture Interrupt: Off // Compare A Match Interrupt: Off // Compare B Match Interrupt: Off // Compare C Match Interrupt: Off For more details, see the datasheet. The timer will tick every 0.5ms once and will interrupt the program (temporarily stop) and run commands contained in the interrupt service routine.Piece of program below are the commands that are carried out during the timer interrupt. ISR(TIMER1_OVF_vect) { static unsigned char i; TCNT1H=0xB7; TCNT1L=0x1B; i++; PORTC=i; if(i>255) { i=0; } } For these applications led connected to PORTC. So that every time the timer interrupt not counting from 0, the initial value of necessary charging timer. Its value is obtained from 46 875 to be converted to hexadecimal numbers B71B. Previously DDR PORTC made in order to switch the output mode display. moving led