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
2.2.1
Pin Descriptions
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-
4
8155AS–AVR–06/08
ATMEL [ ATMEL CORPORATION ]
