Select essential peripherals for ATmega328

 Essential peripherals for ATmega328

The 5 peripherals that can be interfaced with an Atmega328P are, UART, SPI, ADC, Timer/Counter (PWM), I2C, devices are many and varied.



The ATmega328's Universal Asynchronous Receiver Transmitter (UART) allows for communication with a PC and other devices, such as GPS receivers. Here's some information about UART and the ATmega328: 
  • UART theory
    UART is a serial communication protocol that transmits data based on bits. It works by adding a start bit, parity bit, and stop bit to parallel data from the data bus, and then sending the data packet serially, bit by bit. 
  • UART in the ATmega328
    The ATmega328's UART port is initialized, operated, and maintained by several IO registers. 
  • UART loopback
    UART has a loopback function that can be used for debugging or diagnostics. In this mode, data sent from the TX is received by the RX input. 
  • ATmega328
    The ATmega328 is an 8-bit AVR microcontroller that is often used in Arduino boards. It is known for its high performance and low power consumption. 



The Serial Peripheral Interface (SPI) is a data transfer protocol that allows the ATmega328 microcontroller to communicate with other devices. Here's some information about the SPI protocol and its use with the ATmega328: 
  • How it works
    SPI is a point-to-point bus that uses four signals: clock (SCLK), master output/slave input (MOSI), master input/slave output (MISO), and slave select (SS). The master device generates the SCLK signal for synchronization. 
  • How to configure it
    When using the SPI in master mode, the SS pin must be configured as an output pin before enabling the SPI. If the SS pin is still configured as an input pin when the SPI is enabled, the SPI will immediately switch to slave mode if a low level is applied to the pin. 
  • How to use it
    Polling is the most common method used in master mode because it provides the fastest communication. 
  • What it's used for
    The SPI is used for transferring programs to AVR microcontrollers, interfacing with SD cards, and more. 
The ATmega328 is an 8-bit AVR microcontroller that's often used in Arduino boards like the Arduino Uno and Arduino Fio.


Here's some information about the analog-to-digital converter (ADC) in the Atmel ATmega328P microcontroller: 
  • Conversion
    The ADC converts an analog voltage into a digital value. The ATmega328P can convert the voltage to a 10-bit number from 0 to 1023 or an 8-bit number from 0 to 255. 
  • Input
    The ADC can select its input from any of six inputs on the chip. The input voltage should be less than VREF to avoid ADC saturation. 
  • ADC Control Registers
    The ADC Control Registers (ADCSRA and ADCSRB) have the following bits: 
    • ADEN: Enables the ADC module 
    • ADSC: Initiates a single conversion 
    • ADATE: Enables ADC Auto Trigger 
    • ADIF: ADC Interrupt Flag 
    • ADIE: Enables interrupts 
  • ADC modes
    The ADC has different modes, including: 
    • Window Comparator: Detects if the ADC result is above or below a threshold value. This mode can be used to monitor a signal or signal low battery or overcharge. 
    • Differential Input: Applies the difference in voltage of two analog inputs to the ADC module. 

  • Here's some information about the ATmega328's time/counter (PWM) theory: 
    • PWM modes
      The ATmega328 has multiple PWM modes, including Fast PWM, Phase-correct PWM, Clear Timer on Compare Match, and Normal Mode. 
    • Timers
      The ATmega328 has three timers: Timer 0 and Timer 2 are 8-bit timers, and Timer 1 is a 16-bit timer. 
    • Prescalers
      Each timer has a prescaler that divides the system clock to generate the timer clock. The prescale factor can be 1, 8, 64, 256, or 1024. 
    • Output compare registers
      Each timer has two output compare registers that control the PWM width for each timer's output. 
    • Duty cycle and frequency
      The duty cycle is the speed of the PWM signal, while the frequency remains constant. 
    • Parameters
      The PWM parameters include frequency, resolution, and duty cycle numerator. 
    • Programming
      To program PWM, you need to understand the role of each bit in the registers that control the function. 

  • Here's some information about I2C theory for the ATmega328: 
    • Pins
      The ATmega328P uses pins 27 and 28 for I2C data and clock. When I2C isn't in use, these pins can be used as general I/O ports. 
    • Baud rate
      The internal I2C hardware requires the baud rate (I2C clock rate) to be set before any transfers can take place. 
    • Multiple masters
      I2C allows multiple masters to be on the bus and share the same slave device. However, multiple masters sharing the same SDA and SCL bus lines can cause communication issues and data corruption. To solve this, synchronization and arbitration algorithms are used. 
    • Controller and peripheral
      The terms "master" and "slave" are now considered obsolete and have been replaced with "controller" and "peripheral". 
    • Frequency
      When the ATmega328P is clocked at 8MHz, the firmware can function on an I2C-bus at speeds up to 100KHz. 
    • Voltage
      The ATmega328 operates between 1.8-5.5 volts. 
    I2C is commonly used for reading hardware monitors, sensors, and real-time clocks. It can also be used for controlling actuators, accessing low-speed DACs and ADCs, and controlling LCD or OLED displays. 


mega 328 is one of the most commonly used Micro controllers with open source platform amongst many hobbyist and industrial communities. The simplicity and the low power of Atmega 328 helps design many prototype boards which could be used in numerous applications.The Atmega 328 includes 6 analog inputs, 14 digital I/O pins (6 amongst these could be used as PWM outputs), a crystal oscillator with 16MHz frequency.

Board Features

  • Plug & Play Interface Connectivity.
  • Professional EMI/RFI Complaint PCB Layout Design
  • Modular Block design makes Easy access & quick prototyping
  • FRC connectivity features minimize the connection Error.
  • High-Quality Grade PCB with wooden Enclosure.
  • RS232, RS485, USB communication port.
  • On Board WiFi / Bluetooth Connectivity
  • 8 interfacing LED's
  • 1*4 Menu Keypad
  • 4*4 Matrix Keypad
  • 7 Segment Multiplexed Display
  • 16*2 LCD & OLED Display
  • ADC & DAC Card
  • 23 general purpose I/O lines
  • The DIP40 locking device for reuse of ATMEGA microcontroller.
  • Supports ATMEGA 16,32,64 chips 40 pin DIP package.
  • DC Motor/ Stepper Motor Driver.
  • Power Supply 3.3V and 5V SD CARD Interface.
  • RTC & EEPROM Interface.
  • Relay, Buzzer.
  • 1xTemperature Sensor.
  • 3x Analog Test POT.
  • 3.3 to 5V Level Converter.

On Board DIY Projects

  • Digital clock using RTC DS1307 & 16x2LCD
  • Digital lock using Hex Keypad & 16x2LCD
  • Digital password enabled access control system
  • Temperature sensing & controlling relay
  • Temperature sensing & speed control of motor
  • Simple pulse input seven segment counter
  • Realtime Temperatuure sensing & Login to SD card
  • Data Login through RS232 serial interface
  • Modbus master/slave communication
  • Bluetooth controlled appliance through Relay
  • Timer enabled Relay
  • Motor controlling using WiFi
  • LED controlling through PC (USB Interface)
  • 4 digit random number generator
  • Graphic icon display using OLED
  • Menu controlled LED chaser
  • Dice game using OLE
  • Snake game using OLED
  • Star war game using OLED
  • Pong game using OLED




1. Power Supply                                                                      17. 1*4 Keypad Switches                                                         
2. Power On Switch18. RDL BUS FRC Connector
3. Voltage Regulator19. 4*4 Keypad Matrix
4. OLED Display20. ATMEGA328 Controller
5. Digital Input Switch21. 7 Segment Display
6. ADC (Variable Resistor POT)22. 2*4 LED's
7. Temperature Sensor LM3523. Jumper Setting for UART Select Pins
8. RTC24. 16*2 LCD Display
9. L298 Driver25. WiFi/XBEE Module
10. Logic Level Converter26. RS485 Module
11. Buzzer27. On Board ISP Programmer
12. Relay 28. Jumper Settings for UART TTL
13. SD Card Holder29. USB Port
14. Jumper Settings for I2C RTC30. DB9 Serial Female Connector
15. EEPROM31. Power Indicator
16. Jumper Settings for EEPROM


Scope of Learning Experiments:

  • LED blinking.
  • 8 bit LED Left shift, Right shift and counting operation.
  • Keypad  Interrupt Interface
  • 16*2 LCD interface.
  • Matrix Keypad Interface.
  • ADC& DAC interface.
  • Traffic Light Signal Interface.
  • 8 bit DIP switch interface.
  • 7 Segment interface.
  • L298 Driver for DC Motor and Stepper motor interface.
  • Elevator Interface.
  • Buzzer, Relay interface.
  • RS485, RS232 serial communication
  •  PWM Interface
  • UART Operation
  •  RTC DS1307I2C protocol interface.
  • AT24C04 EEPROM I2C protocol interface.
  • RF/WiFiCommunication.
  •  SPI protocol interface
  • Temperature Sensor Interface.






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