Datasheet

4
ATmega32A [DATASHEET]
Atmel-8155D-AVR-ATmega32A-Datasheet_02/2014
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 ATmega32A provides the following features: 32Kbytes of In-System Programmable Flash Program memory
with Read-While-Write capabilities, 1024bytes EEPROM, 2Kbyte 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 compare 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 Oscillator, 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 Interrupt or Hardware Reset. In Power-save mode, the Asynchronous Timer con-
tinues 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 non-
volatile 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 opera-
tion. 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 embed-
ded control applications.
The Atmel AVR ATmega32A 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 symmetrical drive characteristics with both
high sink and source capability. When pins PA0 to PA7 are used as inputs and are externally pulled low, they will
source current if the internal pull-up resistors are activated. The Port A pins are tri-stated when a reset condition
becomes active, even if the clock is not running.
2.2.4 Port B (PB7:PB0)
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buf-
fers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are
externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a
reset condition becomes active, even if the clock is not running.