4

8155AS–AVR–06/08

ATmega32A

The 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 con-

ventional CISC microcontrollers.

The ATmega32A provides the following features: 32K bytes of In-System Programmable Flash

Program memory with Read-While-Write capabilities, 1024 bytes EEPROM, 2K byte SRAM, 32

general purpose I/O lines, 32 general purpose working registers, a JTAG interface for Boundary-

scan, On-chip Debugging support and programming, three flexible Timer/Counters with com-

pare modes, Internal and External Interrupts, a serial programmable USART, a byte oriented

Two-wire Serial Interface, an 8-channel, 10-bit ADC with optional differential input stage with

programmable gain (TQFP package only), a programmable Watchdog Timer with Internal Oscil-

lator, an SPI serial port, and six software selectable power saving modes. The Idle mode stops

the CPU while allowing the USART, Two-wire interface, A/D Converter, 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 External Inter-

rupt 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/reso-

nator 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 ATmega32A is a powerful microcontroller that provides a highly-flexible and cost-

effective solution to many embedded control applications.

The ATmega32A 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.

2.2

Pin Descriptions

2.2.1

VCC

Digital supply voltage.

2.2.2

GND

Ground.

2.2.3

Port A (PA7:PA0)

Port A serves as the analog inputs to the A/D Converter.

Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins

can provide internal pull-up resistors (selected for each bit). The Port A output buffers have sym-