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ubit-3 PIC Interrupts & Interfacing-I

• PIC Interrupts: Interrupt Vs Polling, IVT, Steps in executing interrupt, Sources of interrupts; Enabling and disabling interrupts, Interrupt registers, Priority of interrupts, Programming of: Timer using interrupts, External hardware interrupts, Serial communication interrupt;
• Interfacing of LED, Interfacing 16X2 LCD (8 bits) and Key board (4 x 4 Matrix), Interfacing Relay & Buzzer.
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• One real-life example of an Interrupt Vector Table (IVT) can be found in microcontrollers or microprocessors used in embedded systems. These systems often have multiple peripherals or devices that can generate interrupts. The IVT is used to handle and route these interrupts to their corresponding interrupt service routines (ISRs).
• For instance, let's consider a microcontroller used in an industrial automation system. This system may have various peripherals connected to it, such as sensors, actuators, and communication modules. Each peripheral can generate interrupts when certain events occur, such as a sensor detecting an object or a communication module receiving data.
• The microcontroller's IVT contains a list of memory addresses, each associated with a specific interrupt number or type. When an interrupt is triggered, the microcontroller uses the interrupt number to index into the IVT and fetches the corresponding ISR address. The microcontroller then jumps to that address to execute the ISR, which handles the specific interrupt and performs the necessary actions.
• For example, if a sensor interrupt occurs, the microcontroller will refer to the IVT to find the ISR address associated with that particular interrupt. It will then jump to that address and execute the ISR code, which might involve reading the sensor data, processing it, and taking appropriate actions based on the sensed information.
• In this way, the IVT enables efficient and organized handling of interrupts in embedded systems, allowing the microcontroller or microprocessor to respond promptly to external events and perform the required tasks.
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• Sure! Let's consider a real-life example of handling an interrupt in a computer system:
• 1. Keyboard Interrupt:
• - Step 1: User presses a key on the keyboard.
• - Step 2: The keyboard controller generates an interrupt signal.
• - Step 3: The interrupt signal is sent to the computer's processor.
• - Step 4: The processor acknowledges the interrupt signal.
• - Step 5: The processor saves the current state of the program being executed.
• - Step 6: The processor looks up the interrupt vector table (IVT) to find the address of the keyboard interrupt service routine (ISR).
• - Step 7: The processor jumps to the ISR and starts executing it.
• - Step 8: The ISR reads the keycode from the keyboard controller.
• - Step 9: The ISR processes the keycode and performs the necessary actions, such as updating the display, triggering a function, or storing the input.
• - Step 10: The ISR clears the interrupt flag to indicate that the interrupt has been handled.
• - Step 11: The processor restores the saved program state.
• - Step 12: The processor resumes the execution of the interrupted program.
• In this example, when a user presses a key on the keyboard, it generates an interrupt that interrupts the current program execution. The processor then follows the steps mentioned above to handle the interrupt, execute the keyboard ISR, and perform the required actions based on the key pressed. Afterward, the processor resumes the execution of the program that was interrupted.
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