What is MSP in ARM cortex processors

Main stack pointer which is the default stack pointer 

On reset the processor jumps to the location pointed by the MSP which is 0x00000000

Why is a pull up used in I2C

Pull up registers are used to set a default state for an I/O pin by making sure that your system doesn’t take high values of current on a constant basis.

What is the difference between exception and interrupt

Interrupts are issued by interval timers and I/O devices; for instance, the arrival of a keystroke from a user sets off an interrupt. Exceptions, on the other hand, are caused either by programming errors or by anomalous conditions that must be handled by the kernel.

ARM Cotex Stack pointer

The ARM cotex M has 2 stack registers

1. PSP - Process Stack Pointer

    * User task uses PSP to track individual Task stack utilisation

2. MSP - Main Stack Pointer

     * The kernel uses MSP to track kernel stack utilisation

     * Hardware interrupts use the kernel stack

Vision based techniques

This technique allows for the detection of hand movements and thus recognising gestures acquied by a camera system with the aid of appropriate image processing software.

Microsoft's kinnect is the most widely available cost effective technology which includes a quarter video graphics array infrared camera and a video graphics array camera(VGA-RGB) both with the frame rate of 30fps.

It had an infrared light emitter that projects nonuniformly distributed dots on the screen detected by the depth infrared sensor.This allows the user to create a depth map of the observed scene.

The image processing software provides identification of the number, position and skeletal joints of the subject inside the scene.

It detects upto a distance of 4 meters

Disadvantages of using Camera

1. Camera enclosure

2. Resource management difficulty

3. Costly Computing

4. High energy consumption

Classification of Embedded Systems

Transformative Systems

A system that collects data from inputs, makes decisions and affects it environment by driving actuators.

Example : Robot control system

Reactive Systems

A system that collects data in a continuous fashion and produce output also in a continuous fashion

Example : Digital signal processing algorithms

Embedded Systems

An Embedded system is a smart device that has a processor that has a special and dedicated purpose.

Real time means that the embedded systems should respond to critical events within a strictly defined time called deadline.

5 types of software functions the processor can perform in an embedded system can perform

1.  Mathematical ana/or data processing operations that is,analyse data and make decisions based on the data.

2. Handling and managing time

3. Real time input/output for the purpose of measurement or control

4. Digital signal processing (DSP) which are mathematical calculations on data streams.

Example: Audio, video,radar,sonar etc..

5. Communication and networking

Bare-Metal Programming

when you write an embedded software around the Hardware libraries without RTOS.

 

Charge Pumps in Embedded Systems

  Charge Pumps are used as power sources in devices where form factor is a constraint along with power consumption.

When we have a active low device.The charging of a capacitor takes place in the idle mode of the system when it's on logic high.

This charge stored in the capacitor is then used as a power supply for the device in it's active mode.