– 131 Powerful Instructions – Most Single-clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 16MIPS Throughput at 16MHz
– On-chip 2-cycle Multiplier
• High Endurance Non-volatile Memory segments
– 32KBytes of In-System Self-programmable Flash program memory
– 1024Bytes EEPROM
– 2KByte Internal SRAM
– Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
– Data retention: 20 years at 85°C/100 years at 25°C
– Optional Boot Code Section with Independent Lock Bits
• In-System Programming by On-chip Boot Program
• True Read-While-Write Operation
– Programming Lock for Software Security
• JTAG (IEEE std. 1149.1 Compliant) Interface
– Boundary-scan Capabilities According to the JTAG Standard
– Extensive On-chip Debug Support
– Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface
• Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes
– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture
Mode
– Real Time Counter with Separate Oscillator
–Four PWM Channels
– 8-channel, 10-bit ADC
• 8 Single-ended Channels
• 7 Differential Channels in TQFP Package Only
• 2 Differential Channels with Programmable Gain at 1x, 10x, or 200x
– Byte-oriented Two-wire Serial Interface
– Programmable Serial USART
– Master/Slave SPI Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
• Special Microcontroller Features
– Power-on Reset and Programmable Brown-out Detection
– Internal Calibrated RC Oscillator
– External and Internal Interrupt Sources
– Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby
The Atmel®AVR® ATmega32A is a low-power CMOS 8-bit microcontroller based on the AVR
enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the
ATmega32A achieves throughputs approaching 1 MIPS per MHz allowing the system designer
to optimize power consumption versus processing speed.
Figure 2-1.Block Diagram
8155CS–AVR–02/11
3
ATmega32A
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 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 Boundaryscan, 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 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 Onchip 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 costeffective 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.
2.2Pin Descriptions
2.2.1VCC
Digital supply voltage.
2.2.2GND
Ground.
2.2.3Port A (PA7:PA0)
Port A serves as the analog inputs to the A/D Converter.
8155CS–AVR–02/11
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
metrical 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.
2.2.4Port 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 buffers 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.
Port B also serves the functions of various special features of the ATmega32A as listed on page
59.
2.2.5Port C (PC7:PC0)
Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port C output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins
PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.
ATmega32A
The TD0 pin is tri-stated unless TAP states that shift out data are entered.
Port C also serves the functions of the JTAG interface and other special features of the
ATmega32A as listed on page 62.
2.2.6Port D (PD7:PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port D also serves the functions of various special features of the ATmega32A as listed on page
64.
2.2.7RESET
Reset Input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in Table 27-1 on page
299. Shorter pulses are not guaranteed to generate a reset.
2.2.8XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
2.2.9XTAL2
Output from the inverting Oscillator amplifier.
8155CS–AVR–02/11
5
2.2.10AVCC
2.2.11AREF
3.Resources
4.Data Retention
ATmega32A
AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to V
through a low-pass filter.
AREF is the analog reference pin for the A/D Converter.
A comprehensive set of development tools, application notes and datasheets are available for
download on http://www.atmel.com/avr.
Note:1.
Reliability Qualification results show that the projected data retention failure rate is much less
than 1 PPM over 20 years at 85°C or 100 years at 25°C.
, even if the ADC is not used. If the ADC is used, it should be connected to V
CC
CC
8155CS–AVR–02/11
6
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