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.