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

Draw the logic circuit of Decimal to BCDencoder, What is an encoder? Draw t...

What is an encoder? Draw the logic circuit of Decimal to BCD encoder and explain its working. Ans. Encoder: It is a combinational logic circuit which converts alphanumeric ch

What is rdram, Direct Rambus DRAM or DRDRAM (sometimes just known as Rambus...

Direct Rambus DRAM or DRDRAM (sometimes just known as Rambus DRAM or RDRAM) is a type of synchronous dynamic RAM. RDRAM was formed by Rambus inc., in the mid-1990s as a replacement

Define a structure, Define a structure. A structure having an ordered g...

Define a structure. A structure having an ordered group of data objects. Unlike the elements of an array, the data objects within a structure can have varied data types. Every

Define the state and instance of properties of object, Define the state and...

Define the state and instance of properties of object A state encompasses all properties of object along with values of each of these properties. An instance is a concr

Define virtual memory, Normal 0 false false false EN-IN...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Ecommerce concepts, Your task is to propose a business that has a Web ...

Your task is to propose a business that has a Web presence on the Internet. Your business may be an online only business or a so-called "clicks and mortar" business. You

Control signal, justify whether the control signal passes through same bus ...

justify whether the control signal passes through same bus as data ,address and instruction or not?

Perceptron training, Perceptron training: Here the weights are initial...

Perceptron training: Here the weights are initially assigned randomly and training examples are needed one after another to tweak the weights in the network. Means all the exa

State the benefits of object oriented modelling, Benefits of object oriente...

Benefits of object oriented Modelling There are many benefits and advantages of object oriented modelling. Emphasis on quality and reuse are the major highlights of OOM. OOM p

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