The spiral model is similar to the incremental model, with more emphasis placed on risk analysis. The spiral model has four phases: Planning, Risk Analysis, Engineering and Evaluation. A software project repeatedly passes through these phases in iterations (called Spirals in this model). The baseline spiral, starting in the planning phase, requirements are gathered and risk is assessed. Each subsequent spirals builds on the baseline spiral. Its one of the software development models like Waterfall, Agile, V-Model.

Planning Phase:

Requirements are gathered during the planning phase. Requirements like ‘BRS’ that is ‘Bussiness Requirement Specifications’ and ‘SRS’ that is ‘System Requirement specifications’.

Risk Analysis:

In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. A prototype is produced at the end of the risk analysis phase. If any risk is found during the risk analysis then alternate solutions are suggested and implemented

Engineering Phase:

In this phase software is developed, along with testing at the end of the phase. Hence in this phase the development and testing is done.

Evaluation phase: This phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral.

Advantages of Spiral model:

1.High amount of risk analysis hence, avoidance of Risk is enhanced.

2.Good for large and mission-critical projects.

3.Strong approval and documentation control.

4.Additional Functionality can be added at a later date.

5.Software is produced early in the software life cycle.

Disadvantages of Spiral model:

1.Can be a costly model to use.

2.Risk analysis requires highly specific expertise.

3.Project’s success is highly dependent on the risk analysis phase.

4.Doesn’t work well for smaller projects.

When to use Spiral model:

1.When costs and risk evaluation is important

2.For medium to high-risk projects

3.Long-term project commitment unwise because of potential

4.changes to economic priorities

5.Users are unsure of their needs

6.Requirements are complex

7.New product line

8.Significant changes are expected (research and exploration)

The first stage in the EDLC (Embedded Development Life Cycle) is requirements gathering. Once the requirements gathering is done, the objectives of designing the system are to be identified. Then we need to design the architecture or the block diagram of the embedded system. Then the detailed design of each block is to be made which will be then implemented as a prototype.

The coding or the embedded programming is the next stage wherein the programming of the system is to be done. Then the testing of the designed system will be done. The testing is a very important phase. There will be various possible inputs that will be given to the system to be tested and based on that the correctness of the system designed will be known. During this testing phase, there may be some improvements required in the prototype, which will be updated accordingly to repeat the designing, coding etc.

Once the system is perfectly tested and found to have no problems, then in it is developed, implemented to be delivered. The system is then in operation.