Atmega8A-AU

Atmega8A-AU

Part Number: Atmega8A-AU

Manufacturer: Microchip Technology

Description: IC MCU 8BIT 8KB FLASH 32TQFP

Shipped from: Shenzhen/HK Warehouse

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Atmega8A-AU Description

The ATmega8A is an 8-bit microcontroller that uses AVR’s enhanced RISC architecture. It was made to use little power. As a result of completing complex instructions in a single clock cycle, the ATmega8A can reach speeds of nearly 1 MIPS per MHz. This gives the person who makes the system the freedom to choose between longer battery life and faster processing.

Features of ATMEGA8A-AU SMD IC

● Advanced RISC Architecture

● High Endurance Nonvolatile Memory segments

● Microchip QTouch

● library support

● Peripheral Features

● Special Microcontroller Features

● I/O and Packages

● Operating Voltages

● Speed Grades

● Power Consumption at 4 MHz, 3V, 25°C

AVR Memories

Overview

The AVR design prioritizes two distinct types of storage: data memory and program memory. The ATmega8A also has a built-in EEPROM memory for storing information. There is a consistent linearity across all three memory domains.

In-System Reprogrammable Flash Program Memory

There is 8K of rewritable flash memory on the ATmega8A’s microchip. The Flash is organized as 4K x 16 bits to accommodate the AVR’s 16- or 32-bit comprehensive instructions. The Flash Program memory space is split in two for added software safety, with one section reserved for the Boot Program and the other for the Application Program. At least 10,000 write/erase the Flash memory support cycles. Addressing the 4K Program memory locations is a breeze with the ATmega8A’s 12-bit wide Program Counter (PC).

EEPROM Data Memory

Data EEPROM memory in the Microchip AVR® ATmega8A measures 512 bytes. It’s a discrete data space where individuals’ bytes can be read from and written to. The EEPROM can withstand at least one hundred thousand programming cycles. Following is a description of the EEPROM Address Registers, the EEPROM Data Register, and the EEPROM Control Register that allow communication between the CPU and the EEPROM.

Power Management and Sleep Modes

● Sleep Modes

Sleep modes make it possible for the application to save power by turning off modules in the MCU that are not being used. The AVR features several sleep modes, allowing the user to adjust the energy consumed to suit the application’s needs better.

● Idle Mode

The MCU enters Idle mode when the SM2:0 bits are written to 000 using the SLEEP instruction. This causes the CPU to stop working, but it allows other components, such as Two-wire Serial Interface,  SPI, USART, Analog Comparator, ADC, Timer/Counters, Watchdog, and the interrupt system, to continue functioning normally. This sleep mode will stop clkCPU and clkFLASH from running, allowing the other clocks to operate normally.

The idle mode makes it possible for the MCU to respond to both internally generated and externally triggered interrupts, such as the Timer Overflow and USART Transmit Complete interrupts. Suppose it is not necessary to wake up from the Analog Comparator interrupt. In that case, the Analog Comparator can be shut down by setting the ACD bit in the Analog Comparator Control and Status Register – ACSR. This register is located in the exact location as the Analog Comparator Control and Status Register. In Idle mode, this will result in a decrease in the amount of power consumed. When you switch to this mode, the conversion process will begin immediately if the ADC is active.

● ADC Noise Reduction Mode

When the SLEEP command is sent, the MCU enters ADC Noise Reduction mode by setting the SM2:0 bits to 001. This stops the CPU but keeps the ADC, external interrupts, Two-wire Serial Interface address watch, Timer/Counter2, and Watchdog running (if enabled). While other clocks continue to operate, clkI/O, clkCPU, and clkFLASH are effectively disabled during this sleep state.

This reduces the background noise experienced by the ADC, allowing for more precise readings. The ADC will immediately begin a conversion if this mode is selected. The ADC Conversion Complete interrupt is the only other interrupt that can bring the MCU out of ADC Noise Reduction mode. Other interrupts that can do so include the External Reset, the Watchdog Reset, the Brown-out Reset, the Two-wire Serial Interface address match interrupt, the Timer/Counter2 interrupt, the SPM/EEPROM ready interrupt, and the external level interrupts on INT0 and INT1.

● Power-down Mode

The SLEEP instruction causes the MCU to go into Power-down mode when the SM2:0 bits are written to 010. The External Oscillator will be disabled in this mode, but the External Interrupts, Two-wire Serial Interface Address Watch, and Watchdog will continue functioning normally (if enabled). An external reset can wake up the MCU, and a watchdog reset, a brown-out reset, an address-match interrupt on the Two-wire Serial Interface, or a superficial level interrupt on INT0 or INT1. In sleep mode, all clocks are effectively disabled, leaving just asynchronous components active.

● Power-save Mode

The MCU enters a power-saving mode by setting the SM2:0 bits to 011 with the SLEEP command. Unlike Power-down, Timer/Counter2 can continue to operate in this mode if it is clocked asynchronously by setting the AS2 bit in ASSR. Suppose the appropriate bits in TIMSK are set to enable interrupts from Timer/Counter2, and the global interrupt enable bit in SREG is also set. In that case, the device will be able to be woken up by either a Timer Overflow or an Output Compare event from Timer/Counter2.

Power-down mode is preferred over Powersave mode if the asynchronous timer is not clocked asynchronously, as the contents of the asynchronous timer’s registers are undefined at wake-up in the Power-save way if AS2 is 0. In sleep mode, all clocks except clkASY are disabled; thus, only asynchronous modules, such as Timer/Counter 2, can run.

Conclusion

The ATMEGA8A-AU is an 8-bit high-performance, low-power AVR RISC-based microcontroller that includes a 6-channel 10-bit A/D converter, a programmable watchdog timer, and an internal oscillator. It has 23 general-purpose I/O lines, internal and external interrupts, 32 general-purpose working registers, serial programmable USART, a byte-oriented Two-Wire serial interface, and 2.7–5.5V operation. The device balances power consumption and processing performance by executing full instructions in a single clock cycle, which results in throughputs that are close to 1 MIPS per MHz.

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