Embedded Programming Systems

An embedded system is some combination of computer hardware and software which is a special-purpose computer system designed to perform one or a few dedicated functions.

Some examples of Embedded Programming System are :

• Alarm / security system
• Automobile cruise control
• Heating / air conditioning thermostat
• Microwave oven
• Anti-skid braking controller
• Traffic light controller
• Vending machine
• Gas pump
• Handheld Sudoku game
• Irrigation system controller
• Mars Rover 

Running Of An Embedded Program : 

          Reset vector - 

• Written in assembly
• Very first thing that runs at start-up and considered as hardware-specific code
• Perform simple functions like setting up the processor into a pre-defined steady state by configuring registers
• Jumps to the startup code
  
  
  Startup code - 

• First software-specific code that runs
• Its job is basically to set up the software environment so that C code can run on top
• Define the stack pointers and heap pointers
• It will execute main()
  
  
  Application code - 

• Written as hardware-agnostic 
• The application code make use of library functions
• Libraries are usually statically linked in embedded systems
  
  Libraries - 

• Provide primitive C functions
• Implement things like software floating-point support
• There are hardware-specific libraries to access the I/O devices
  
  Interrupt/Exception handler -
• These are routines that run at random times during normal code execution
• Written in assembly