Watch the Video Tutorial: Interrupts are one of the most powerful features of PIC Microcontrollers, interrupts make it possible to create applications that can respond to external stimulus in real time. An interrupt is basically an event that requires the microcontroller to stop normal program execution and then to jump to execute a program code related to the event causing the interrupt. An interrupt requires immediate attention, only once the microcontroller will finish executing the interrupt code, then it can go back to continue with the main program. The interrupt code is called Interrupt Service Routine (ISR) or Interrupt Handler. Here is a simple example to understand interrupts, let say you are playing a game with your phone and Suddenly your mobile phone rings somebody is calling you.
Universal Serial Bus. Use the integrated USB HID terminal of mikroC PRO for PIC. Void USB_Interrupt_Proc(void).
Your phone will immediately leave the game and start ringing. Only once you are done with the call, then the phone will jump back to the game. This process is similar to ISR execution. You can think the main service routine in this case as playing the game and the ringing of the mobile phone as causing an interrupt. This initiates your mobile phone conversation which is similar to executing Interrupt Service Routine (ISR). If there were no interrupt, while playing the game, the microcontroller would time to time pause the game and monitor if there is no one trying to call you. As you can see, this is not an efficient way of programming as it consumes all its processing time for monitoring and they can be a possibility of missing a short process that can require immediate attention.
The best way is to leave the microcontroller do its normal main program, and if there is nothing to do, let the microcontroller go into sleep mode and be awaken only to respond to an interrupt that occurs. This can save power and much needed processor power especially if the application if battery powered. The processes of continuous monitoring is known as POLLING. Interrupts can be very useful in many applications such as:.
Fail safe applications: Applications which require the immediate attention of the microcontroller when there is a fault in the system can use interrupts. For example, in an emergency such as a power failure in an hazardous environment where a the microcontroller has to take some precise coordinated actions like switching off the system immediately in an orderly manner.
Arduino Serial Interrupts
In such applications an external interrupt can force the microcontroller to stop whatever it is doing and take immediate action. Performing routine tasks: If an application requires the microcontroller to perform routine tasks at precise times, such as blinking a status LED, reading inputs of sensors connected to the microcontroller exactly every few millisecond. A timer interrupt scheduled with the required timing can divert the microcontroller from normal program execution to accomplish the task at the precise time required. To check if a certain tasks have been completed: Some applications may need to know when a task, such as an A/D conversion, is completed, or instead of keep on listening (polling) for an incoming data from an UART or USB port for example, an interrupt could be raise immediately when an A/D conversion is done or when there is an incoming data instead of keeping the microcontroller doing nothing but waiting for this to happen. Interrupts in PIC PIC18F452 Different PIC Microcontrollers have different interrupts, but most have both the core and peripheral interrupt sources. Always check your device datasheet to find out more about the interrupts. Figure 1: PIC18F452 Like most PIC18F series PIC Microcontrollers, the PIC18F452 has the following interrupts:.
Mikroc Pro For Arm
External: External edge-triggered interrupt on INT0, INT1, and INT2 pins (RB0, RB1 and RB2). In this simple Peripheral UART Rx event interrupt Example using the which has 2 UART modules, Whenever there is data sent to the serial port (the PIC USART), it will trigger the USART receive interrupt (interrupt on serial RX pin), if the sent character is 1, the microcontroller will execute the Interrupt Service Routine code, any other character will be ignored. In the main code, the Green LED connected to RB4 blinks at an interval of 1 seconds. The Interrupt Service Routine code will blink the Red LED connected to RB5 at an interval of 200ms 5 times.