Nucleus – Interrupt Handling

In most of RTOS, whenever an interrupt arrives, the interrupt vector table’s corresponding routine is invoked to execute some piece of code to take the required action for that interrupt.

Nucleus RTOS had peculiar interrupt handling mechanism which is not found in some of those RTOS mechanism. Nucleus interrupts are handled in two phases called LISR (Low level ISR-Interrupt Service Routine) and HISR (High level ISR) parts.

The LISR routine is similar to existing RTOS’s ISR, but the important difference is if required more processing, it activates the corresponding HISR.  During LISR processing, only limited system calls are allowed and minimal processing is done. This ensures to respond to interrupt in very quick manner and reduces the latency for the same.

The HISR are scheduled similar to the task. They have priority 0 to 2 that are the highest priority levels defined by Nucleus. The remaining 3 to 255 priority levels are given to the tasks.  The lower the priority value, the higher the chances of task or HISR to get scheduled. The HISR can access most of the system calls.

Moreover, whenever the scheduler runs, it checks any activated HISR first. If found, it schedules all HISR before any of the task is scheduled.  This allows to perform the required extra processing in HISR after LISR is executed without spending much time in ISR.

Project10tothe100

Google has come out with a super initiative called a project10tothe100 to help people. It’s so simple, just come out with an idea which can affect lots of people on different categories. The best thing about this initiative is that Google commits to invest $10 million for different kinds of ideas.

Idea Submission date Oct 20. Submit your idea here

Ummmmm… what idea???? I must get one to help people.

How to start singing?

Most of people are interested in singing. Some are really good singers performing in public, but some are bathroom singers. I started with the latter and have sung in choir. It’s really amazing.

Without proper voice or hitting the right notes, singing looks raucous but there is always a  way to learn. I believe that we can train our body or part of the body for the desired function. Some people are gifted with good vocal sounds, and the others can train it.  I found this nice piece of videos on youtube.com which is really helpful who wants to learn the basics of singing. I hope it will be helpful to you. There are three parts and all of them are really good, especially the person has put the things in nice order.

Part1

Part 2

Part 3