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

What does the ''suppress dialog'' do, What does the 'SUPPRESS DIALOG' do? ...

What does the 'SUPPRESS DIALOG' do? Suppressing of whole screens is possible with this command.  This command permits us to perform screen processing "in the background".  Sup

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?

What is indexing, What is indexing? Specific fields shown on each scann...

What is indexing? Specific fields shown on each scanned document are provided to our organization to make the systematic arrangement of your records. This process is designed t

Microprocessor MIPS Full Adder and Divider with overflow, I need to write a...

I need to write a 32 bit adder in MIPS without using the Add command and a divider as well.

Dfd, dfd for big bazaar

dfd for big bazaar

Block format and disk layout on cd-rom, Q. Block Format and Disk Layout on ...

Q. Block Format and Disk Layout on CD-ROM? A typical block format is displayed in Figure (a). It comprises the subsequent fields: Sync: Sync field identifies beginning o

Which technique are used to gain on the number pairs, Explain the technique...

Explain the techniques, which are used to gain on the number pairs. In rural areas, subscribers are usually dispersed. This is both unessential and expensive to give a dedicate

What is the last entry in all bdc tables, What is the last entry in all BDC...

What is the last entry in all BDC tables? In all BDC tables the last entry is to save the data by using the field name BDC_OKCODE and a field value of '/11'.

Grounding a variable - first-order logic, Grounding a variable - first-orde...

Grounding a variable - first-order logic: The perform of making ourselves clear about a variable by introducing an exists or a forall sign is called quantifying the variable.

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