Operation of micro controller, Computer Engineering

Assignment Help:

Consider the hardware design as shown. Within the target system the EPROM would contain the hex data as shown below

  Address  Assembly code
  8000             86
  8001             fe
  8002             8b
  8003             01
.  .........
  FFFE             80
  FFFF             00
 
On power on the microprocessor issues a reset which causes the processor to go into an interrupt mode, because the interrupt is a reset, the microprocessor reads the two top bytes from memory i.e fffe and ffff. These are called the initial program counter RESET vectors. In this case the processor would then load in the 16 bit address 8000 and load this directly into the program counter (PC). This causes the processor to jump to address 8000 and start the actual program. The processor then reads the next byte from address 8000; this is 86 Hex and translates it to a load A instruction with immediate data where the data follows in the next byte. The PC is incremented by 1 i.e 8001 and fe in read in . This takes two cycles and termed the 'Fetch cycle'. The next stage is the microprocessor to perform the instruction i.e. transfer the data fe into A, this is termed the 'Execution cycle'. The whole cycle starts again, i.e. the PC is incremented to 8002 and the command 8b (ADDA) is fetched and interpreted as a ADDA, the PC in incremented to 8003 and the data is read in i.e. 1. The command is then executed and the next instruction read in at 8004 and so on. A day in the life of the micro controller is one of fetching and executing. The initial data in the EPROM at address fffe, ffff is termed the reset vector and is an reserved area of memory for the programmers (us) to place vector address i.e. start address of programs to deal with exceptions i.e.  Clock Fail, IRQ, Timer output, Serial communications etc.

The full vector table is shown  .Although we have not actually used the stack, the emulator which we use to debug hardware/software programs uses a small part of it , therefore it is important that we initialise the stack , therefore the full program for adding two numbers is shown below

                   Name     add
                   P6811
                  org $8000    ; Start address of program   
  main:       Lds #$1ff     ; Set SP to top of internal Ram
                 Ldaa  #$fe   
                 adda  #$1   
 loop0:      jmp loop0       ; loop forever
                 org $fffe
                 FDB main    ;Reset vectors
                END
The bold sections are termed assembler directives and are used to control the assembler; the simplest ones are ORG which stands for origin, i.e. start code at this address  , the P6811 indicates 68HC11 processor and END which tells the assembler to stop. FDB informs the assembler to insert a double byte i.e. 16 bits of the address labelled main i.e. 8000.


Related Discussions:- Operation of micro controller

Constants - first-order logic, Constants - first-order logic: Constant...

Constants - first-order logic: Constants are things that is cannot be changed, like as england, black and barbara. So then they stand for one thing only, so that can be confu

Game playing techniques - artificial intelligence, Game Playing techniques ...

Game Playing techniques - artificial intelligence: Now we have dispensed with the essential background material for Artificial Intelligence problem solving techniques, and we m

Explain pipelining, Define pipelining Pipelining is an efficient way of...

Define pipelining Pipelining is an efficient way of organizing concurrent activity in a computer system. The processor implements the program by fetching and implementing instr

Determine the performance of a parallel algorithm, Q. Determine the perform...

Q. Determine the performance of a parallel algorithm? One more method of determining the performance of a parallel algorithm can be performed after calculating a parameter know

Cell array variable , a)   Make a cell array variable that would kept for a...

a)   Make a cell array variable that would kept for a student his or her name, university id number, and GPA.  Print this information. b) Make a structure variable that would kept

Explain non-pre-emptive algorithms, Explain non-pre-emptive algorithms?   ...

Explain non-pre-emptive algorithms?   Non preemptive algorithms: In this algorithm a job is provided to CPU for execution as long as the job is non-completed the CPU cannot

Procedure level- levels of parallel processing, Procedure Level Here, p...

Procedure Level Here, parallelism is accessible in the form of parallel executable procedures. In this situation, the design of the algorithm plays a main role. For example eac

Database, I got a graduate level database assignment which is due at Dec 8,...

I got a graduate level database assignment which is due at Dec 8, 11:59p.m. Can you finish it on time in high quality?

What is process control block, What is process control block?  Each pro...

What is process control block?  Each process is shown in the OS by a process control block. It having many pieces of information associated with a specific process.

What is a daemon, What is a Daemon? A daemon is a method that detaches ...

What is a Daemon? A daemon is a method that detaches itself from the terminal and runs, disconnected, in the background, waiting for requests and responding to them. It can als

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd