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

Coding advantages of casex or casez, Coding advantages of casex or casez ...

Coding advantages of casex or casez By using casex or casez has the following coding advantages: -  It reduces number of lines, especially if the number of bits had been m

Two properties of recursion, Two properties of recursion are:- 1. A sm...

Two properties of recursion are:- 1. A smallest, base case that is processed without recursion and acts as decision criterion for stopping the method of computation and 2.

Define external layer, Define external layer? The external layer is the...

Define external layer? The external layer is the plane at which the user sees and interacts with the data, that is, the data format in the user interface.  This data format is

Receive a message, Receive a message. tid is integer task identifier of tra...

Receive a message. tid is integer task identifier of transmitting process supplied by user and msgtag is message tag supplied by user( must be non negative integer). The process re

What is a message passing system, Distributed System 1. What is a messa...

Distributed System 1. What is a message passing system? Discuss the desirable features of a message passing system. 2. Discuss the implementation of RPC Mechanism in detail.

Pc cross assembler, 1.0 By working throughthe first time guide this will ga...

1.0 By working throughthe first time guide this will gain familiarity with the on board monitor and the PC cross assembler  After connecting the system to the terminal program,

Does average velocity differ from its instantaneous velocity, Q. When an ob...

Q. When an object travels with constant velocity does its average velocity during any time interval differ from its instantaneous velocity at any instant? Answer:- No It i

Explain time slot interchange, Discuss the basic structure and principle of...

Discuss the basic structure and principle of operation of Time Slot Interchange (TSI) switch with the help of a neat diagram. Principle of time slot interchange  Time

Representation scheme in ai, Representation scheme in AI: • It's fairl...

Representation scheme in AI: • It's fairly trouble-free to represent knowledge in this way. It allows us to be expressive enough to represent largely knowledge, while being co

Can we use flow logic control key words in abap/4, Can we use flow logic co...

Can we use flow logic control key words in ABAP/4 and vice-versa The flow control  of a dynpro having os a few statements that syntactically ressemble ABAP/4  statements .Thou

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