Prepare a ATmega328 for programming

 Here are some things to consider when programming an ATmega328: 

• Components

  You'll need an ATmega328P IC, an 8MHz crystal oscillator, and a 22pF capacitor. 
• Initial connections

  Make the following initial connections on a breadboard: 

  • Pin 1 to Vcc via a 10K resistor 
  • Pin 7 and Pin 20 to Vcc 
  • Pin 8 and Pin 22 to Gnd 
  • Pin 9 and Pin 10 to the crystal oscillator 
• Bootloading

  You can upload a bootloader to the microcontroller, which allows you to install new firmware without an external programmer. 
• Programming

  You can use the Arduino IDE to program the ATmega328P. To do this, you can: 

  1. Select the correct board in the Arduino IDE by going to Tools > Board and selecting "ATmega328 on a breadboard (8 MHz internal clock)" 
  2. Select the correct programmer in the Arduino IDE by going to Tools > Programmer and selecting "Arduino as ISP" 
• Programming voltage

  The ATmega328P operates between 1.8-5.5 volts. 

ATmega328 PORT, SEE THE EXTERNAL PDF

The ATmega328 has three ports: Port B, Port C, and Port D. Here are some details about each port: 

• Port B: An 8-bit bi-directional I/O port with internal pull-up resistors. 
• Port C: An analog port with six pins. 
• Port D: Pins 0–7. 

The ATmega328 is an AVR 8-bit microcontroller. Here are some other features of the ATmega328:

• Low power consumption
• Fast processing speed
• 32 KB of programmable flash memory
• 32 general purpose registers
• 2 KB of SRAM
• 1 KB of EEPROM
• Three timer/counters 

atmega328 bootloader circuit,

What's a Bootloader?

Microcontrollers are usually programmed through a programmer unless you have a piece of firmware in your microcontroller that allows installing new firmware without the need of an external programmer. This is called a bootloader.

Not Using a Bootloader

If you want to use the full program space (flash) of the chip or avoid the bootloader delay, you can burn your sketches using an external programmer.

Burning the Bootloader

To burn the bootloader, you'll need to buy an AVR-ISP (in-system programmer), USBtinyISP or build a ParallelProgrammer. The programmer should be connected to the ICSP pins (the 2 by 3 pin header) - make sure you plug it in the right way. The board must be powered by an external power supply or the USB port.

Make sure you have the right item selected in the Tools | Board menu. Then, just launch the appropriate command from the Tools > Burn Bootloader menu of the Arduino environment. Burning the bootloader may take 15 seconds or more, so be patient.

ISP of ATmega328,

An Arduino Uno can be used as an in-system programmer (ISP) to program an ATmega328P microcontroller: 

Step	Description
Upload the ArduinoISP sketch	Open the ArduinoISP sketch in the Arduino IDE, and upload it to the Arduino
Wire the Arduino and ATmega328P	Connect the Arduino and ATmega328P as shown in a diagram
Select the board and programmer	Select the board and programmer in the Tools menu
Burn the bootloader	Run the Burn Bootloader option in the Tools menu
Wait for a successful status	If the status is successful, the bootloader is programmed

Some things to keep in mind include: 

• The Arduino IDE's pin number 5 refers to the fifth pin of the Arduino board, not the fifth pin of the ATmega328P. 
• If the ATmega328P already has a bootloader, you can skip the process of burning the bootloader. 
• You can disable the reset on serial connect by disconnecting the DTR line from the USB serial adapter, or by using a pull up resistor. 

In-system programming (ISP) allows some microcontrollers to be programmed while they're still installed in a system. 

comparision of ATmega 8  and ATmega328,

The ATmega8 and ATmega328 are both microcontrollers, but they have different features: 

• Memory

  The ATmega8 has 8Kbytes of in-system self-programmable flash memory, 512bytes of EEPROM, and 1Kbyte of internal SRAM. The ATmega328 has 32Kbytes of ISP flash memory, 1Kbyte of EEPROM, and 2Kbytes of SRAM. 
• Timers and counters

  The ATmega8 has two 8-bit timer/counters, one 16-bit timer/counter, and a real time counter. The ATmega328 has three flexible timer/counters. 
• Other features

  The ATmega8 has three PWM channels and an 8-channel ADC. The ATmega328 has a 6-channel 10-bit A/D converter, a programmable watchdog timer, and five software-selectable power-saving modes. 
• Operation

  The ATmega8 and ATmega328 both operate between 1.8 and 5.5 volts. 

other differences,

1. Architecture and Core

• Atmega8:
• 8-bit AVR microcontroller.
• Based on the AVR architecture with a lower instruction set.
• Atmega328:
• Also an 8-bit AVR microcontroller, but it features a more advanced architecture.
• Supports a richer instruction set and improved performance.

2. Memory

• Atmega8:
• Flash memory: 8 KB
• SRAM: 1 KB
• EEPROM: 512 bytes
• Atmega328:
• Flash memory: 32 KB (with 0.5 KB used by the bootloader)
• SRAM: 2 KB
• EEPROM: 1 KB

3. I/O Pins

• Atmega8:
• 23 I/O pins (with 18 capable of PWM).
• Atmega328:
• 32 I/O pins (with 6 capable of PWM and 6 capable of analog input).

4. Clock Speed

• Atmega8:
• Typically runs at 16 MHz.
• Atmega328:
• Also typically runs at 16 MHz but can support higher speeds in some configurations.

5. Peripheral Features

• Atmega8:
• Fewer timers and peripherals compared to the Atmega328.
• Atmega328:
• More advanced timers, additional serial communication options (like USART), and improved ADC capabilities.

6. Power Consumption

• Atmega8:
• Generally has a slightly higher power consumption due to its older design.
• Atmega328:
• More power-efficient, especially in low-power modes.

7. Applications

• Atmega8:
• Suitable for simpler projects with fewer requirements.
• Atmega328:
• More versatile, used in a wider range of applications, making it the preferred choice for modern Arduino projects.