The Microchip AVR core combines a rich instruction set with 32 general purpose working registers. All the 32registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers tobe accessed in one single instruction executed in one clock cycle. The resulting architecture is more codeefficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.
The ATmega128A provides the following features: 128Kbytes of In-System Programmable Flash withRead- While-Write capabilities, 4Kbytes EEPROM, 4Kbytes SRAM, 53 general purpose I/O lines, 32general purpose working registers, Real Time Counter (RTC), four flexible Timer/Counters with comparemodes and PWM, 2 USARTs, one byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC withoptional differential input stage with programmable gain, programmable Watchdog Timer with InternalOscillator, one SPI serial port, IEEE std. 1149.1 compliant JTAG test interface, also used for accessingthe On-chip Debug system and programming and six software selectable power saving modes. The Idlemode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt system tocontinue functioning.
The Power-down mode saves the register contents but freezes the Oscillator,disabling all other chip functions until the next interrupt or Hardware Reset. In Power-save mode, theasynchronous timer continues to run, allowing the user to maintain a timer base while the rest of thedevice is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules exceptAsynchronous Timer and ADC, to minimize switching noise during ADC conversions. In Standby mode,the Crystal/Resonator Oscillator is running while the rest of the device is sleeping.
This allows very faststart-up combined with low power consumption. In Extended Standby mode, both the main Oscillator andthe Asynchronous Timer continue to run. The device is manufactured using Microchip’s high-density nonvolatile memory technology. The On-chip ISPFlash allows the program memory to be reprogrammed in-system through an SPI serial interface, by aconventional nonvolatile memory programmer, or by an On-chip Boot program running on the AVR core.
The boot program can use any interface to download the application program in the application Flashmemory. Software in the Boot Flash section will continue to run while the Application Flash section isupdated, providing true Read- While-Write operation. By combining an 8-bit RISC CPU with In-SystemSelf-Programmable Flash on a monolithic chip, the Microchip ATmega128A is a powerful microcontroller thatprovides a highly flexible and cost effective solution to many embedded control application.
The ATmega128A AVR is supported with a full suite of program and system development tools including:C compilers, macro assemblers, program debugger/simulators, in-circuit emulators, and evaluation kits.