Microcontroller with 4/8/16/32K
1. Pin Configurations
Figure 1-1. Pinout ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
TQFP Top View PDIP (PCINT7/XTAL2/TOSC2) PB7
PC1 (ADC1/PCINT9)
NOTE: Bottom pad should be soldered to ground.
NOTE: Bottom pad should be soldered to ground.
1
PD2 (INT0/PCINT18) PD1 (TXD/PCINT17) PD0 (RXD/PCINT16) PC6 (RESET/PCINT14) PC5 (ADC5/SCL/PCINT13) PC4 (ADC4/SDA/PCINT12) PC3 (ADC3/PCINT11) PC2 (ADC2/PCINT10)
8 9 10 11 12 13 14
28 27 26 25 24 23 22
(PCINT22/OC0A/AIN0) PD6 (PCINT23/AIN1) PD7 (PCINT0/CLKO/ICP1) PB0 (PCINT1/OC1A) PB1 (PCINT2/SS/OC1B) PB2 (PCINT3/OC2A/MOSI) PB3 (PCINT4/MISO) PB4
PD2 (INT0/PCINT18) PD1 (TXD/PCINT17) PD0 (RXD/PCINT16) PC6 (RESET/PCINT14) PC5 (ADC5/SCL/PCINT13) PC4 (ADC4/SDA/PCINT12) PC3 (ADC3/PCINT11) (PCINT21/OC0B/T1) PD5 (PCINT22/OC0A/AIN0) PD6 (PCINT23/AIN1) PD7 (PCINT0/CLKO/ICP1) PB0 (PCINT1/OC1A) PB1 (PCINT2/SS/OC1B) PB2 (PCINT3/OC2A/MOSI) PB3 (PCINT4/MISO) PB4
9 10 11 12 13 14 15 16
32 31 30 29 28 27 26 25
PD2 (INT0/PCINT18) PD1 (TXD/PCINT17) PD0 (RXD/PCINT16) PC6 (RESET/PCINT14) PC5 (ADC5/SCL/PCINT13) PC4 (ADC4/SDA/PCINT12) PC3 (ADC3/PCINT11) PC2 (ADC2/PCINT10)
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
Pin Descriptions
VCC
Digital supply voltage.
GND
Ground.
Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2
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.
Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscil- lator amplifier and input to the internal clock operating circuit.
Depending on the clock selection fuse settings, PB7 can be used as output from the inverting Oscillator amplifier.
If the Internal Calibrated RC Oscillator is used as chip clock source, PB7...6 is used as TOSC2...1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.
The various special features of Port B are elaborated in and ”System Clock and Clock Options”
on page 26.
Port C (PC5:0)
Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The PC5...0 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.
PC6/RESET
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical char- acteristics of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a 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 28-12 on page 323. Shorter pulses are not guaran- teed to generate a Reset.
The various special features of Port C are elaborated in ”Alternate Functions of Port C” on page 86.
Port D (PD7:0)
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.
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
AVCC
AREF
The various special features of Port D are elaborated in ”Alternate Functions of Port D” on page 89.
AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. Note that PC6...4 use digital supply voltage, VCC.
AREF is the analog reference pin for the A/D Converter.
ADC7:6 (TQFP and QFN/MLF Package Only)
In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter.
These pins are powered from the analog supply and serve as 10-bit ADC channels.
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
2. Overview
The ATmega48A/48PA/88A/88PA/168A/168PA/328/328P is a low-power CMOS 8-bit microcon- troller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega48A/48PA/88A/88PA/168A/168PA/328/328P achieves through- puts approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.
Block Diagram
Figure 2-1. Block Diagram
AVCC
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
Watchdog
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
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 ATmega48A/48PA/88A/88PA/168A/168PA/328/328P provides the following features:
4K/8K bytes of In-System Programmable Flash with Read-W hile-W rite capabilities, 256/512/512/1K bytes EEPROM, 512/1K/1K/2K bytes SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible Timer/Counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented 2-wire Serial Interface, an SPI serial port, a 6-channel 10-bit ADC (8 channels in TQFP and QFN/MLF packages), a pro- grammable Watchdog Timer with internal Oscillator, and five software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, USART, 2-wire Serial Interface, 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 com- bined with low power consumption.
The device is manufactured using Atmel’s high density non-volatile 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 pro- gram 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 ATmega48A/48PA/88A/88PA/168A/168PA/328/328P is a powerful microcontroller that provides a highly flexible and cost effective solution to many embedded con- trol applications.
The ATmega48A/48PA/88A/88PA/168A/168PA/328/328P 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.
Comparison Between Processors
The ATmega48A/48PA/88A/88PA/168A/168PA/328/328P differ only in memory sizes, boot loader support, and interrupt vector sizes. Table 2-1 summarizes the different memory and inter- rupt vector sizes for the devices.
Table 2-1. Memory Size Summary
Device Flash EEPROM RAM Interrupt Vector Size
ATmega48A 4K Bytes 256 Bytes 512 Bytes 1 instruction word/vector ATmega48PA 4K Bytes 256 Bytes 512 Bytes 1 instruction word/vector ATmega88A 8K Bytes 512 Bytes 1K Bytes 1 instruction word/vector ATmega88PA 8K Bytes 512 Bytes 1K Bytes 1 instruction word/vector ATmega168A 16K Bytes 512 Bytes 1K Bytes 2 instruction words/vector
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P
Table 2-1. Memory Size Summary
Device Flash EEPROM RAM Interrupt Vector Size
ATmega168PA 16K Bytes 512 Bytes 1K Bytes 2 instruction words/vector ATmega328 32K Bytes 1K Bytes 2K Bytes 2 instruction words/vector ATmega328P 32K Bytes 1K Bytes 2K Bytes 2 instruction words/vector
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P support a real Read-While-Write Self-Pro- gramming mechanism. There is a separate Boot Loader Section, and the SPM instruction can only execute from there. In ATmega 48A/48PA there is no Read-While-Write support and no separate Boot Loader Section. The SPM instruction can execute from the entire Flash.
3. Resources
A comprehensive set of development tools, application notes and datasheets are available for download on http://www.atmel.com/avr.