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

Application and factors related to scanners, Q. Application and factors rel...

Q. Application and factors related to Scanners? When you purchase a scanner there are various factors which can be looked at: Compatibility of Scanner with your Computer, The T

Determine the output waveforms for and and or gates, The voltage waveforms ...

The voltage waveforms shown in given fig. are applied at the inputs of 2-input AND and OR gates. Determine the output waveforms. Ans. The Output waveforms for AND and O

How adaptive transmission helps tcp to maximize connection, How adaptive tr...

How adaptive transmission helps TCP to maximize throughput on each connection? To know how adaptive retransmission helps TCP maximize throughput upon all connection, see a case

Problems for decision tree learning, Appropriate Problems for Decision Tree...

Appropriate Problems for Decision Tree Learning : However remember there that is a skilled job in "AI" to choose exactly the right learning representation ormethod for a parti

Explain the term recursion, Explain the term recursion A recursive functi...

Explain the term recursion A recursive function is one which calls itself. Recursive functions are useful in evaluating certain types of mathematical function. Here is a recursiv

Connectives - first-order logic , Connectives - first-order logic: We ...

Connectives - first-order logic: We can string predicates all together in a sentence by using connectives into the same way to conduct that we did for propositional logic. We

Name two special purpose registers, Name two special purpose registers. ...

Name two special purpose registers. Index register Stack pointer

What are the special unit related fields and methods, What are the special ...

What are the special unit related fields and methods?   The most significant method (in fact pseudo method) related to units is get_enclosing_unit().  The mostly used field in

Explain the term electronic data interchange (edi), Explain the term Electr...

Explain the term Electronic Data Interchange (EDI). Electronic Data Interchange (EDI) may be generally easy to understand as the replacement of paper-based purchase orders alon

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