memory

ATmega8

ATmega Registers Memory
signpost

General Purpose Input/Output

Learn keyboard_arrow_right
timer

Timers/Counters

Learn keyboard_arrow_right
sync_alt

Serial Communication Interfaces

Learn keyboard_arrow_right

At the intersection of innovation and efficiency lies the ATmega8 Microcontroller. As a member of Atmel's revered AVR series, the ATmega8 has become synonymous with reliability and versatility in the realm of 8-bit microcontrollers.

Whether you're a hobbyist crafting a DIY project or a professional architecting a commercial product, It offers a blend of features that can cater to a broad spectrum of requirements.

ATmega8 Microcontroller

It also features 23 general-purpose I/O pins, 3 timers/counters, a USART, an SPI, and an I2C interface, as well as an 8-channel, 10-bit ADC for converting analog signals to digital values.

Its operating voltage ranges from 2.7V to 5.5V, and it can be set to different power-saving modes to conserve energy.

The ATmega8 microcontroller is available in several different package types, including PDIP, SOIC, and TQFP, making it easy to integrate into different types of systems.

Its versatility and range of features make it a popular choice for a wide range of embedded systems applications, from industrial automation to consumer electronics.

corporate_fare A Glimpse into its Architecture

At the core of the ATmega8 lies the AVR enhanced RISC (Reduced Instruction Set Computing) architecture. Known for its efficiency, this architecture ensures that the ATmega8 executes most of its instructions in a single clock cycle.

startBy executing powerful instructions in a single clock cycle, the ATmega8 achieves throughputs approaching 1MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed.

It has a Harvard architecture, which means that it has separate memory spaces for instructions and data. The AVR architecture is known for its efficient code execution and low power consumption.

The main function of the CPU core is to ensure correct program execution. The CPU must therefore be able to access memories, perform calculations, control peripherals, and handle interrupts.

Block Diagram of the ATmega8
Microcontroller Architecture

To maximize performance and parallelism, the AVR uses a Harvard architecture – with separate memories and buses for program and data. Instructions in the Program memory are executed with a single-level pipelining.

Atmega8 Architecture Block diagram

While one instruction is being executed, the next instruction is pre-fetched from the Program memory. This concept enables instructions to be executed in every clock cycle. The Program memory is In-System Reprogrammable Flash memory.

The fast-access Register File contains 32 × 8-bit general-purpose working registers with a single clock cycle access time. This allows single-cycle Arithmetic Logic Unit (ALU) operation.

memory_alt ATmega8 Pins Configurations

It has 28 pins arranged in two rows, with a 0.1-inch pitch between them. The pinout diagram of ATmega8 is as follows -

Atmega8 Pinouts And Pins Description

Pins Description

VCC

Digital supply voltage.

GND

Ground

Port B (PB7..PB0) XTAL1/XTAL2/TOSC1/ TOSC2

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

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 Oscillator 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 a chip clock source, PB7..6 is used as TOSC2..1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.

Port C (PC5..PC0)

Port C is an 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

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.

Port C (PC6/RESET)

If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical characteristics 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.

Port D (PD7..PD0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

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.

RESET

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.

AVcc

AVCC is the supply voltage pin for the A/D Converter, Port C (3..0), and ADC (7..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 Port C (5..4) use digital supply voltage, VCC.

AREF

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.

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.

functions ATmega8 Alternate Pin Functions

Alternate Functions of Port B

The Port B pins with alternate functions are shown in Table.

Port Pin Alternate Functions
PB7 XTAL2 (Chip Clock Oscillator pin 2)
TOSC2 (Timer Oscillator pin 2)
PB6 XTAL1 (Chip Clock Oscillator pin 1 or External clock input)
TOSC1 (Timer Oscillator pin 1)
PB5 SCK (SPI Bus Master clock Input)
PB4 MISO (SPI Bus Master Input/Slave Output)
PB3 MOSI (SPI Bus Master Output/Slave Input)
OC2 (Timer/Counter2 Output Compare Match Output)
PB2 SS (SPI Bus Master Slave select)
OC1B (Timer/Counter1 Output Compare Match B Output)
PB1 OC1A (Timer/Counter1 Output Compare Match A Output)
PB0 ICP1 (Timer/Counter1 Input Capture Pin)

XTAL2/TOSC2 – Port B, Bit 7

XTAL2: Chip clock Oscillator pin 2. Used as clock pin for crystal Oscillator or Low-frequency crystal Oscillator. When used as a clock pin, the pin can not be used as an I/O pin.

TOSC2: Timer Oscillator pin 2. Used only if the internal calibrated RC Oscillator is selected as a chip clock source, and the asynchronous timer is enabled by the correct setting in ASSR.

When the AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PB7 is disconnected from the port, and becomes the inverting output of the Oscillator amplifier.

In this mode, a crystal Oscillator is connected to this pin, and the pin cannot be used as an I/O pin.

XTAL1/TOSC1 – Port B, Bit 6

XTAL1: Chip clock Oscillator pin 1. Used for all chip clock sources except internal calibrated RC Oscillator. When used as a clock pin, the pin can not be used as an I/O pin.

TOSC1: Timer Oscillator pin 1. Used only if the internal calibrated RC Oscillator is selected as a chip clock source, and the asynchronous timer is enabled by the correct setting in ASSR.

AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PB6 is disconnected from the port, and becomes the input of the inverting Oscillator amplifier.

In this mode, a crystal Oscillator is connected to this pin, and the pin can not be used as an I/O pin.If PB6 is used as a clock pin, DDB6, PORTB6 and PINB6 will all read 0.

SCK – Port B, Bit 5

Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a Slave, this pin is configured as an input regardless of the setting of DDB5.

When the SPI is enabled as a Master, the data direction of this pin is controlled by DDB5.

When the pin is forced by the SPI to be an input, the pull-up can still be controlled by the PORTB5 bit.

MISO – Port B, Bit 4

Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a Master, this pin is configured as an input regardless of the setting of DDB4.

When the SPI is enabled as a Slave, the data direction of this pin is controlled by DDB4.

When the pin is forced by the SPI to be an input, the pull-up can still be controlled by the PORTB4 bit.

overview_key Diverse I/O and Peripheral Support

The ATmega8 isn't just about processing power; it's also about communication and interfacing.

GPIO Pins

With 23 versatile pins, the ATmega8 can both listen to and command a plethora of external devices. This is what enables it to be the brain of numerous applications, from robots to remote controls.

USART

Serial communication is pivotal in today's interconnected world. The full-duplex USART module in the ATmega8 ensures it can communicate seamlessly with other devices, be it for data transfer, debugging, or command execution.

Timers

Time management is crucial in many applications. Whether you're generating a PWM signal to control motor speed or creating time-based interrupts, the ATmega8's timers are up to the task.

ADC

The world around us is analog, and the 10-bit ADC in the ATmega8 ensures the digital world understands it. With 6 channels, it can sense a myriad of inputs, from temperature to light intensity.

power Power Management - The Heartbeat of Any Device

Every piece of technology needs to manage its energy consumption, and the ATmega8 is no exception.

  • Active Mode

    When the microcontroller is executing instructions, it's in the Active mode. This is where it consumes the most power, but it's also when it's most productive.

  • Idle Mode

    In this mode, the CPU is halted while allowing peripherals like timers and UART to continue their operations. It's a middle ground, conserving more power than the Active mode but being ready to jump into action quickly.

  • Power-down Mode

    This is the ATmega8's deep sleep. Most of its operations are halted, leading to significant power savings. It's ideal for battery-operated devices that need to conserve energy over prolonged periods.

  • ADC Noise Reduction Mode

    For applications that require precise analog-to-digital conversions, noise can be a hindrance. This mode minimizes the system's electronic noise, enhancing ADC accuracy.

safety_check Atemga8 Special Features & Safety

The ATmega8 isn't just powerful; it's reliable. It has a number of special features that make it well-suited for embedded systems applications.

Interrupt Handling

The microcontroller can handle both internal and external interrupts, allowing it to respond quickly to events that require immediate attention.

In-circuit programming

The microcontroller can be programmed in-circuit using a serial programming interface, which makes it easy to update the program code without removing the microcontroller from the system.

Watchdog timer

The microcontroller has a built-in watchdog timer that can be used to reset the system if it becomes unresponsive.

Brown-out detector

The microcontroller has a brown-out detector that can detect when the power supply voltage drops below a certain level and take appropriate action to avoid data corruption.

apps Applications - Where Does the ATmega8 Shine?

The versatility of the ATmega8 is manifested in its diverse applications.

  1. Home Automation

    In a world striving for convenience, the ATmega8 finds its place in smart homes, driving devices like automated lights, security systems, and thermostats.

  2. Robotics

    Robots require sensors, motors, and a brain to make decisions. The ATmega8, with its GPIO capabilities, timers, and ADC, often plays the role of that brain.

  3. Wearable Technology

    Compact, power-efficient, and potent, the ATmega8 is ideal for wearable tech, from fitness trackers to smart glasses.

  4. Gaming Consoles

    Handheld gaming devices, with their need for real-time responses, often rely on the prowess of the ATmega8.

The ATmega8 microcontroller is more than just a piece of silicon; it's a testament to what's possible when efficiency meets innovation. As we advance into an era dominated by smart devices and interconnected systems, the role of robust microcontrollers like the ATmega8 will undoubtedly be pivotal. Bridging the analog and digital worlds, driving innovations, and ensuring reliability, the ATmega8 continues to stand tall in the realm of embedded systems.

signpost

General Purpose Input/Output

The ATmega8 microcontroller has three 8-bit I/O ports, named PORTB, PORTC, and PORTD. Each port has a corresponding data direction register (DDRB, DDRC, and DDRD) that controls whether each pin is configured as an input or output.

When a pin is configured as an output, its logic level can be set to either high (logic 1) or low (logic 0) by writing to the corresponding bit in the PORT register. When a pin is configured as an input, its logic level can be read by reading the corresponding bit in the PIN register.

Start Learnning

timer

Timers/Counters

Timers and counters are integral components of microcontrollers, playing a pivotal role in time management, event counting, and pulse generation. The ATmega8, with its versatile timers/counters, stands as a testament to this. These modules allow developers to craft applications that require precise time intervals, event counting, and pulse width modulation.

Whether you're generating precise delays, creating waveforms, or controlling analog devices using digital signals, ATmega8 timers are your go-to tool. Dive in to master their capabilities and applications.

Start Learnning

sync_alt

Serial Communication Interfaces

The ATmega8 microcontroller, renowned for its versatility, houses robust serial communication interfaces, enabling seamless data transmission. Essential for IoT projects and embedded systems, its UART (Universal Asynchronous Receiver-Transmitter) empowers real-time two-way communication. With SPI (Serial Peripheral Interface) and TWI (Two Wire Interface), ATmega8 ensures rapid data sharing with peripherals, further enhancing its appeal to developers.

As technology propels towards interconnected devices, ATmega8's serial interfaces provide the foundation for sophisticated applications. Dive deeper into its capabilities, from simple data logging to complex IoT systems, and discover how ATmega8 stands as a cornerstone in serial communication. Harness the power of ATmega8's interfaces for unparalleled performance in your projects.

Start Learnning

Search