Objective
This page provides a basic interrupt code example for the ATmega328PB MCU. The project configures the Timer/Counter1 module to operate in Clear-Timer-On-Compare (CTC) mode, and, on a period match, generates an interrupt event every 100 mS. The ISR manipulates a "tick" signal variable that is used by the main loop to toggle LED0 every 100 mS.
Materials
Hardware Tools
| Tool | About | Purchase |
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 ATmega328PB Xplained Mini
Evaluation Kit |
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Software Tools
| Tool | About | Installers |
Installation
Instructions |
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| Windows | Linux | Mac OSX | |||
 Atmel® Studio
Integrated Development Environment |
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Exercise Files
| File | Download |
Installation
Instructions |
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| Windows | Linux | Mac OSX | ||
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Example Project
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We recommend extracting the .zip file to your C:\ folder.
You should see the folder C:\MTT\8avr\mega\code-examples\interrupt-example\8avr-mega-int-usage containing the solution 8avr-mega-int-usage.atsln
Connection Diagram
The USART0 module on the target ATmega328PB device is connected to the USART interface on the mEDBG chip. The mEDBG chip performs USB-serial conversion by enumerating as a CDC-class virtual COM port on the PC and presenting the target USART data on this interface. The mEDBG also controls the programming/debug interface on the target device, as well as supplying a 16MHz clock when the Xplained board is connected via USB cable to a PC. The LED0 is connected to port PB5 as shown:
Procedure
Attach the ATmega328PB Xplained Mini board to your computer using a USB A-to-MicroB cable. Start Atmel Studio 7. If the board has been successfully enumerated, you should see the board image come up in Studio as shown:
The board is identified by the last four digits in its serial number (see sticker on bottom of board). In the above example, the last four digits are "3352"
1
Open the Solution
To understand how interrupts were configured and enabled in this example (main.c file), please review the megaAVR® Interrupt Configuration page.
2
Rebuild the Solution
3
Program the Fuses
There are several key hardware configuration settings that need to be configured. The following fuse settings need to be programmed into the device:
- HIGH: 0xDF
- LOW: 0xC0
- EXT: 0xFC
Enter the Device Programming dialog as shown:
In the Device Programming dialog box, select the Tool, Device and Interface as shown, then press Apply:
To verify a connection, select Read and verify that a Device Signature is found:
Select the Fuses sub-section, Enter the 3 Fuse Byte Values above, then press Program as shown:
4
Program the Hex File
While still in the Device Programming dialog box, select "Memories" as shown. The path to the solution's hex file should already be listed in the dialog. Press Program as shown:
Results
Conclusions
This project has provided an example of how to setup and use interrupts on the megaAVR MCU.