f. In general, to configure and operate the interrupt mechanism for any peripheral, what are the steps need to be done? [3 Marks]
For the interrupt to work, three things to be done:
- Its IE(Interrupt Enable) bit to be set.
- Its IF(Interrupt Flag) status bit to be reset.
- Its Priority to be set.
What should be done for ISR?
For the ISR (Interrupt Service Routine) to be configured and executed, the following steps need to be done:
1. Define the ISR: Write the code for handling the interrupt in the ISR function. This function will be executed whenever the associated interrupt occurs.
2. Map the ISR to the correct interrupt: Register the ISR function to the specific interrupt vector or register provided by the peripheral or microcontroller. This ensures that the correct ISR is called when the interrupt is triggered.
3. Enable the interrupt: Enable the interrupt by setting the corresponding interrupt enable bit in the interrupt control register or the peripheral's control register. This allows the microcontroller or peripheral to react to the interrupt by calling the registered ISR.
It is important to note that these steps may vary depending on the specific microcontroller or peripheral being used. The documentation or datasheet of the device should provide details on how to configure and operate the interrupt mechanism.
For the ISR (Interrupt Service Routine) to be properly executed, the following steps need to be followed:
1. Define the ISR: Start by defining the ISR, which is a subroutine or function that will handle the interrupt when it occurs. The ISR should have a specific format and include any necessary parameters or variables.
2. Register the ISR: Register the ISR with the appropriate interrupt vector or table. This is typically done by assigning the address of the ISR to a specific location in memory that corresponds to the interrupt number or vector.
3. Enable the Interrupt: Enable the interrupt for the peripheral or device that you want to generate the interrupt. This is usually done by setting the interrupt enable bit (IE) in the control register of the peripheral.
4. Set the Interrupt Priority: If the processor supports interrupt priority levels, you may need to set the priority level for the interrupt. This determines the order in which interrupts are serviced and can be important for determining the responsiveness of the system.
5. Clear the Interrupt Flag: When the interrupt occurs, the interrupt flag (IF) for the peripheral or device will be set. In the ISR, it is important to clear the interrupt flag to acknowledge that the interrupt has been serviced. This is usually done by writing a specific value or bit pattern to the control register of the peripheral.
6. Execute the ISR: Once the interrupt is acknowledged and the interrupt flag is cleared, the ISR will be executed. This step involves performing any necessary actions or tasks to handle the interrupt and then returning control back to the main program.
It is important to note that the specific steps and details may vary depending on the microcontroller or processor architecture being used. Therefore, it is recommended to consult the documentation or datasheet for the specific device to properly configure and operate the interrupt mechanism for any peripheral.
For the Interrupt Service Routine (ISR) to be properly implemented, the following steps need to be taken:
1. Define the ISR: Create a function or subroutine in your code that will be executed when the interrupt occurs. This ISR should typically have a specific name and signature that matches the requirements of the interrupt controller or the programming language being used.
2. Enable the Interrupt: Before the ISR can be triggered, the interrupt needs to be enabled. This is usually done by setting the interrupt enable bit (IE) for the specific peripheral or interrupt source you want to handle. This can typically be achieved by writing to a specific register or using specific API calls provided by the hardware or software framework you are working with.
3. Register the ISR: Next, you need to register the ISR with the interrupt controller or the corresponding interrupt vector table. This step ensures that when the interrupt occurs, the registered ISR will be executed. The process of registering an ISR will be platform-specific and might involve configuring specific registers or using specific API calls.
4. Implement the ISR: Inside the ISR, you need to write the code that handles the interrupt event. This typically involves performing the necessary operations or tasks specific to the interrupt source. For example, if the interrupt is generated by a UART transmission, you may need to read and process the received data.
5. Exit the ISR: After the necessary operations are performed, you need to exit the ISR by returning or executing any requisite exit instructions. In some cases, additional cleanup or bookkeeping tasks may be required before leaving the ISR.
It is important to note that the specific steps and requirements for implementing an ISR may differ depending on the platform, programming language, and framework being used. Therefore, it is essential to refer to the documentation or resources provided by the hardware or software vendors to ensure the correct configuration and operation of the interrupt mechanism.