1. Description
The Atmel AVR core combines a rich instruction set with 32 general purpose working registers. All the 32
registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to
be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code
efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.
The ATmega128A provides the following features: 128Kbytes of In-System Programmable Flash with
Read- While-Write capabilities, 4Kbytes EEPROM, 4Kbytes SRAM, 53 general purpose I/O lines, 32
general purpose working registers, Real Time Counter (RTC), four flexible Timer/Counters with compare
modes and PWM, 2 USARTs, one byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC with
optional differential input stage with programmable gain, programmable Watchdog Timer with Internal
Oscillator, one SPI serial port, IEEE std. 1149.1 compliant JTAG test interface, also used for accessing
the On-chip Debug system and programming and six software selectable power saving modes. The Idle
mode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt system to
continue 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, the
asynchronous timer continues to run, allowing the user to maintain a timer base while the rest of the
device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except
Asynchronous 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 fast
start-up combined with low power consumption. In Extended Standby mode, both the main Oscillator and
the Asynchronous Timer continue to run.
The device is manufactured using Atmel’s high-density nonvolatile memory technology. The On-chip ISP
Flash allows the program memory to be reprogrammed in-system through an SPI serial interface, by a
conventional 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 Flash
memory. Software in the Boot Flash section will continue to run while the Application Flash section is
updated, providing true Read- While-Write operation. By combining an 8-bit RISC CPU with In-System
Self-Programmable Flash on a monolithic chip, the Atmel ATmega128A is a powerful microcontroller that
provides 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.
Atmel ATmega128A [DATASHEET]
Atmel-8151JS-8-bit AVR Microcontroller_Datasheet_Summary-09/2015
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