Q1. Describe the function of the volatile keyword in embedded C?
A1. It’s job is to tell the compiler that a variable should not be optimised.
- It should be used only when there can be sudden change of the value of that particular variable.
- Quite useful for the registers that are memory mapped.
Q2. Is it possible to declare a variable as both a constant and a volatile variable?
A2. Yes it woul bd make sense that the compiler wants to keep the volatile variable constant.
- However the value can be altered through external intervention.
Q3. Describe what is a null pointer?
A3. It is one of the popular macros used in c programming.
- It does not indicate any valid memory location.Hence it is used to find out whether a particular memory address is valid or not.
Q4,. State the size of integer, pointer, and their corresponding pointers?
A4. The corresponding sizes are as follows:-
- Integer – 4 bytes
- Character – 1 byte
- Integer pointer – 8 bytes on 64 bit machine and 4 bytes on 32 bit machine
- Character pointer – 8 bytes on 64 bit machine and 4 bytes on 32 bit machine.
Q5. Describe what is an ISR in Embedded C?
A5. It is essentially a subroutine that is activated whenever an interrupt is encountered in the main program.
Q6. Is the printf statement applicable within the interrupt routine?
A6. It is not employed within a service routine as it is thread damaging, and employs dynamic memory location.
- It could have a negative effect on the time of ISR and even latency.
Q7. Describe what are inline functions?
A7. These function are usually used in the ARM architecture.
- They are essentially small functions with small definitions.
- Function body takes effect in each call to inline function.
Q8.Describe whats is an RTOS?
A8. It is a.k.a Real time Operating System.
- It comprises of an useful component known as the scheduler:- It organises which process to be executed on the processor based on priorities assigned by the user.
- Multitasking is efficient based on the number of cores of processor and optimisation.
- Kernel preemption should be available.
- The dispatch latency of the interrupt should be shortened
- The latency taken for switching context must be short
- The multiple processes taking place within the RTOS should be both reliable as well as time efficient.
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