Atmel Atmega128 OverviewALU ParticularsRISC Architecture133, Mostly single cycle instructions2 Address instructions (opcode, Rs, Rd, offset)32x8 Register file-6 can be used as 16-bit registersHarvard architecture Status Register (half carry, sign, OV, Neg, Zero, Carry, GIE)-not stored when entering ISRAtmel Atmega128 OverviewMemory SystemThere are four separate memory spaces on the AVR-Program space:-128K byte (64Kx16) in-circuit flash programmable-Endurance minimum of 10K cycles-Can be accessed by program for storage of constants-SRAM Data Memory:-4K bytes-variable storage area -i/o and peripherals are located here also-EEPROM:-4K bytes-separate data space-single byte read/write access via EEPROM access registers-8.5mS to write data (slow but durable)Atmel Atmega128 OverviewMemory System-Mega128 board has added 32K external SRAM memory-Uses multiplexed lower address and data-Addr bit 15 selects external memory if XMEM register is programmedAtmel Atmega128 OverviewTimers and CountersTCNT0-8-bit -internal synchronous clock or external asynchronous 32Khz clock-especially used for time keeping with 32Khz clock-has no external pin for clocking, only two crystal sourcesAtmel Atmega128 OverviewTimers and CountersTCNT1, TCNT3-16 bit timer/counter, requires special access method-clocked by internal clock or by external pin-3 output compare registers and output pins (set, reset, toggle)-multiple compare registers -input capture register captures when external event happened -ADC interrupt input can capture time at which some voltage is detectedTimers and CountersTCNT1, TCNT3Atmel Atmega128 OverviewAtmel Atmega128 OverviewTimers and CountersTCNT2-8-bit counter/timer-like TCNT0 but has external clocking capability-has PWM capabilityAtmel Atmega128 OverviewTimer/counter prescalers-separate prescalers available for TCNT1,2,3 only-used when operating from internal or external clock pin-clock can be prescaled by 8, 64, 256 or 102Atmel Atmega128 OverviewInterrupts 30 interrupt sources-external pin levels or edges-timer/counters-SPI, USART, and TWI Rx and Tx complete-ADC conversion complete-EEPROM ready-input capture, external event capture, ADC interruptAll interrupts are vectored-reset is vector zero (highest priority)-all other interrupts are prioritized in ascending order-interrupt response time is 4 cycles-interrupt return time is also 4 cyclesAtmel Atmega128 OverviewSerial InterfacesSPI (Serial Peripheral Interface)-full duplex, three wire interface-MSB first or last, programmable bit rates to clock/2Atmel Atmega128 OverviewSerial InterfacesUSART(universal synchronous asynchronous receiver transmitter)-2 identical and separate units, USART0, USART1-full duplex serial communications-programmable number of bits, parity, stop bit, error detection-interrupt on tx done, rx ready, or tx register emptyAtmel Atmega128 OverviewSerial InterfacesUSART0,1Atmel Atmega128 OverviewSerial InterfacesTWI (two wire interface)-half duplex serial communications -7 bit device addressing-multi-master operation-400khz data rate-I2C compatibleAtmel Atmega128 OverviewAnalog to Digital Converter-10-bit resolution-13-260uS conversion time-8 multiplexed single input channels-7 differential input channels-selectable internal reference (2.56V)-input range 0-Vcc-interrupt on completionAnalog to Digital ConverterAtmel Atmega128 OverviewAtmel Atmega128