Configure port to send logic, Computer Engineering

Assignment Help:

Configure port A for the lower 4 bits to be inputs and the upper 4 bits to be outputs. The program should chase a logic one from Pa4 -> Pa7, depending upon the condition of Pa0-Pa3 the speed of chase is increased.

Pa0  = 1  Slow Counter  
Pa1  = 1  Counter   
Pa2  = 1  Counter    
Pa3  = 1  Fast  Counter    
 
If all Pa0, Pa1, Pa2, Pa3 = 0 wait
 
The only major difference is the data direction i.e. this configures 4 input lines Pa0-Pa3 and 4 output lines Pa4-Pa7

Paddr
Bit7  Bit6  Bit5  Bit4  Bit3  Bit2  Bit1  Bit0
1  1  1  1  0  0  0  0
 
The full program is shown below

                  name first
padr          equ $0000
paddr        equ $0001
                 org $500
                 ldaa #$f0
                 staa paddr     set up half in and half out
loop0        ldaa #$10
                 staa padr     send data
                 jsr delay
                 ldaa #$20
                 staa padr     send data
                 jsr delay 
                ldaa #$40
                staa padr     send data
                jsr delay
                ldaa #$80
                staa padr     send data
                jsr delay
                jmp loop0
delay        ldab padr    ;get input from port a
                andb #$0f    ;mask of lower nibble only

                beq delay    ;repeat till selected
                ldab padr    ;get port a data again
                andb #$8    ; mask off bit 3 pa3
                bne loop3    ;if select go to loop3
                ldab padr    ;get port a data again
                andb #$4    ; mask off bit 2 pa2
                bne loop4    ;if select go to loop4
                ldab padr    ;get port a data again
                andb #$2    ; mask off bit 1 pa1
                bne loop5    ;if select go to loop5
                ldx #$ffff    ;assume pa0 is pressed load up x with ffff
                jmp loop1    ;carry on
loop2        ldx #$1    ;load up X with 1 fast
                jmp loop1    ;carry on
loop3        ldx #$f      ;load X with f
                jmp loop1
loop4       ldx #$ff    ;load x with ff
               jmp loop1
loop5      ldx #$fff    ;load x with fff slow
loop1      ldab #$1f    ;nested loop
loop6      decb
              bne loop6
              dex
             bne loop1    ;loop till zero
             rts               ;return back to main
             end


Related Discussions:- Configure port to send logic

excitation diagram indicating , a.  Sketch the excitation diagram indicati...

a.  Sketch the excitation diagram indicating the last states and next states. b. Build the circuit using a Synchronous Counter with JK FF and NAND gates only. Replicate the circ

Smart card & e-cash, Smart Card & E-Cash E-cash storable smart cards ca...

Smart Card & E-Cash E-cash storable smart cards can kept and dispense cash electronically, making bills and coins lesser essential. It transfers funds over phone lines, making

How are the instructions provided to computer, Let's answer our second ques...

Let's answer our second question first. All computers have a Unit which performs arithmetic and logical functions. This Unit is called as Arithmetic and Logic Unit (ALU). However h

Final implementation of object oriented modelling, Final Implementation of ...

Final Implementation of Object oriented modelling Final Implementation: At this phase, the final execution of classes and  relationships developed while object design takes

Explain single instruction and multiple data stream (simd), Normal 0 ...

Normal 0 false false false EN-US X-NONE X-NONE Figure: SIMD Organisation

Determine the define byte - assembler directives, Determine the Define Byte...

Determine the Define Byte - Assembler directives DB (Define Byte): DB directive defines a byte-type variable (i.e. a variable that occupies one byte of memory space). In a give

System software, System Software System software is a group of progr...

System Software System software is a group of programs written to service another programs. Some system software (e.g., compilers editors and file management utilities) proc

Elements of composition, The Elements of composition are the formal languag...

The Elements of composition are the formal language used to communicate in the visual arts. The elements of composition can be loosely broken into 5 main elements, Line, shape, val

What is task identifier, Q. What is task identifier? Each and every PVM...

Q. What is task identifier? Each and every PVM task is uniquely recognized by an integer known as task identifier (TID) assigned by local pvmd. Messages are received from and s

What is application analysis, What is application analysis? The purpose...

What is application analysis? The purpose of analysis is to understand the problem so that a correct design can be constructed. The application analysis focuses on major applic

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