rotate_ conditional and io

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Rotate and Shift



Rotate and Shift

Contains instructions to rotate and shiftbits around.

Logical Shift Left/Right (LSL/LSR):Shifts bits to left or right by inserting zeros.



LSL (Logical Shift Left)

0



LSR (Logical Shift Right)

0



Example: LSLD0 = $000000AAD1 = $00000008LSL.W D1,D0

0 0 A AD0.W =

A A 0 0D0.W =LSL

0 0

Pushed out

0000 0000 1010 1010 0000 0000



Example: LSRD0 = $000000AALSR.W #4,D0

0 0 A AD0.W =

0 0 0 AD0.W =

LSR 0

Pushed out

0 0 A AD0.W =

0000 0000 0000 1010 1010



ROL & ROR (Rotate Left/Right)

Pushes out MSB, and moves the bits tothe back.

C set to last bit pushed out.



ROL (Rotate Left)



ROR (Rotate Right)



Example: ROLD0 = $000000ABD1 = $00000003ROL.B D1,D0

0 1 0 1D0.B = 1 1 0 1

1 0 1 0D0.B = 1 0 1 1

1 0 1 0D0.B = 1 0

Pushed out…

1 0 1 1 1

And sent to back…

New D0 = $0000005D



Example: RORD0 = $000000ABROR.B #4,D0

1 0 1 0D0.B =

1 0 1 1D0.B =

Pushed out…

1 0 1 1

1 0 1 0

1 0 1 0D0.B = 1 0 1 11 0 1 1

And sent to front…

New D0 = $000000DA



Branch Instructions



Branch Instructions

Branch instructions are instructions thattransfer execution of the program to

another location. The new location is marked by a label.

The format is BRA <label>.



Unconditional Branching Example

Instruction #1

Instruction #2

BRA HERE

Instruction #3

Instruction #4

HERE Instruction #5

Instruction #6

Never executed.



Infinite Loop Example

REPEAT Instructions #1

Instructions #2…

Instructions #n

BRA REPEAT



Compare and Branch

In BRA, the program will branch unconditionallywhen it encounters the BRA command.

A branch instruction may also be given a

condition:Called Bcc (Branch when condition is true). If the tested condition is true, then branch to <label>. If the tested condition is not true, then just execute

next line. To test the condition, the CMP (Compare)

instruction is used.



Bcc Flowchart

START

Evaluate condition

using CMP

Condition =TRUE?

Go to LABEL Execute next line

FINISH

TRUE FALSE



Conditions (cc)

Bcc

BGT

BGE

BEQ

BNE

BLE

BLT

D0.B > D1.B

D0.B ≥ D1.B

D0.B = D1.B

D0.B ≠ D1.B

D0.B ≤ D1.B

D0.B < D1.B

CMP.B D1,D0

*(Antonakos, pg. 84)

BRA: Branch Unconditionally.



Bcc Format

LABEL Instructions #1

Instructions #2

… Instructions #n

Test Condition (CMP)

Bcc LABEL

Instructions after Bcc…

If condition = TRUE

If conditions = FALSE



Bcc Format

Test Condition (CMP)

Bcc LABEL

Instructions #1

Instructions #2

…

Instructions #n

LABEL Instructions after LABEL…

If conditions = TRUE,Instructions 1 nwill not be executed

If conditions = FALSE,Instructions after LABELexecuted line-by-line.



If…Else

If…Else is tests a condition, and

determines whether it is true or not.

If the condition is true, execute a block ofstatements.

Else, execute another block of statements.



Example: If…Else Using Bcc

Check the byte stored in D3. If D3 > 10,clear the byte. Else, add 3 to the value

stored in D3.



FlowchartSTART

Move valueto D3

D3 > 10?

Clear D3 D3 = D3 + 3

FINISH

True False



Assembly Code

START ORG $1000

MOVE.B #11,D3

CMP.B #10,D3

BGT MORE

BLE LESS

MORE CLR.B D3

BRA FINISH

LESS ADD.B #3,D3

FINISH END START

D3.B > 10

D3.B < 10



Example: If…Else Using Bcc

Check the value of 1 byte stored atmemory location $2000. If the value is

equal to zero, then replace it with $FF.Else, do not change its value.



Flowchart



Program

START ORG $1000

MOVE.B $2000,D0

CMP.B #0,D0

BEQ ISZERO

BNE NOTZERO

ISZERO MOVE.B #$FF,$2000

BRA HABIS

NOTZERO NOP (NO OPERATION)

HABIS END START



Flowchart



Flowchart

Graphical method to plan flow of ourprograms.

Shows program‟s step-by-step operation. Easy to understand and analyze.

Can be used to write organized programs.



Flowchart

Basic shapes:

Terminator.

Process.Decision.

Input/Output.

Connectors.



Basic Shapes – Terminator

Indicates beginning and end of flowchart.

Once at beginning, once at end.

Examples:

START FINISH



Basic Shapes - Process

Describes actions to be done.

Represented as rectangles.

Short description of process in rectangle.

Example:

A = A + B Reset Ports Clear D0



Basic Shapes - Decision

Shows alternative program flow based oncondition.

Represented as diamond shape. Should have 2 arrows, representing

TRUE and FALSE program flows.

Can be used in “if…else”, “while”, and “for”situations.



Basic Shapes - Decision

Examples:

D0 = 3?

TRUE FALSE

Port is active?TRUE

FALSE



Basic Shapes – Input/Output

Shows the process of inputting oroutputting data.

Represented using rhombus. Examples:

Input D0 Show calculationresults



Basic Shapes - Connectors

Used to link large process flows together.

Represented using circles, with numbers

inside. Numbers indicate connection.

Examples:

1 3



Example: Connector

START

Input D0

Input D1

1

D0 = D0 x D1

1

FINISH



Writing the Program

Once flowchart is complete, write code toimplement program.

Follow program flow closely. Check and fix problems if necessary.



Example 1



Example 1D0

D1

START

Input D0

Input D1

1

D0 = D0 x D1

1

FINISH

Write a program that calculatesthe area of a rectangle usingM68000 assembly language.The length and width of therectangle is stored in D0 and D1.



Translation to Assembly

START

Input D0

Input D1

D0 = D0 x D1

FINISH

START ORG $1000

MOVE.W #$0012,D0

MOVE.W #$0034,D1

MULU D1,D0

END START



Complete Program

START ORG $1000

MOVE.W #$0012,D0

MOVE.W #$0034,D1

MULU D1,D0

END START



Example 2



Example 2

Two numbers are stored in memorylocations $5000 (A) and $6000 (B).

If A is larger than B, then move A tomemory location $7000.

If B is larger than A, then move B to

memory location $7000.



Flowchart & ProgramSTART

ENTER DATAINTO A & B

A > B?

STORE AAT $7000

STORE BAT $7000

FINISH

START ORG $1000

MOVE.B #3,$5000

MOVE.B #4,$6000

MOVE.B $5000,D0

MOVE.B $6000,D1

CMP.B D1,D0

BGT SIMPANA

BLE SIMPANBSIMPANA MOVE.B D0,$7000

BRA HABIS

SIMPANB MOVE.B D1,$7000

HABIS END START

TRUE FALSE



Example 3



Example 3

Memory locations $1100 to $1109contains 10 bytes of data. Write a

program that adds together the 10 bytesand stores them in D1.



Flowchart

START

Input numbersinto memory

locations.

D0 = 10

Load startingaddress into A0

Clear D1

FINISH

D0 = 0?

D1 = D1 + (A0)

FALSE

Go to next

memory location

D0 = D0 - 1

TRUE



START

Input numbersinto memory

locations.

Load startingaddress into A0

ORG $1000

MOVE.B #$11,$1100

MOVE.B #$22,$1102

MOVE.B #$33,$1104MOVE.B #$44,$1106

MOVE.B #$55,$1108

MOVE.B #$66,$110A

MOVE.B #$77,$110C

MOVE.B #$88,$110E

MOVE.B #$99,$1110

MOVE.B #$11,$1112

MOVE.L #$001100,A0



D0 = 10

Clear D1

D0 = 0?

D1 = D1 + (A0)

FALSE

D0 = D0 - 1

MOVE.B #10,D0

CLR.B D1

Go to nextmemory location

CMP.B #$0,D0, LOOP…BNE LOOP

ADD.B (A0),D1

ADD.L #1,A0

FINISH

SUB.B #1,D0

END



Complete Program

START ORG $1000

MOVE.B #$11,$1100

MOVE.B #$22,$1102

MOVE.B #$33,$1104MOVE.B #$44,$1106

MOVE.B #$55,$1108

MOVE.B #$66,$110A

MOVE.B #$77,$110C

MOVE.B #$88,$110E

MOVE.B #$99,$1110

MOVE.B #$11,$1112

MOVE.L #$1100,A0

MOVE.B #10,D0

CLR.B D1

LOOP ADD.B (A0),D1

ADD.L #1,A0SUB.B #1,D0

CMP.B #0,D0

BNE LOOP

END START



I/O Interfacing



I/O Interfacing

M68k can also be used to control devices suchas: Switches.

7-Segment.

LED (Light Emitting Diodes).

DC Motors.

M68k cannot control the devices directly, it hasto use the M68230 I/O chip to control thedevices.



M68230 Interfacing

Memory

CS*

M68k

M68230

Port A

Port B

Port C

Data BusDevice #1

Device #2

Device #3

(LED, Switches, Motor,7-Segment, Keypad, etc.)



Registers in M68230

M68230 contains 23 registers.

Before using the M68230, the M68230 needs tobe initialized.

Initialization is done by configuring certainregisters in the M68230: Port General Control Register.

Port X Control Register (A, B).

Port X Data Direction Register (A, B, C).

Port X Data Register (A, B, C).



Port Addresses: Example

PI/T ADDRESSABLE REGISTER ABBREVIATION ADDRESS

Port General Control Register PGCR $800001

Port A Data Direction Register PADDR $800005

Port B Data Direction Register PBDDR $800007

Port C Data Direction Register PCDDR $800009

Port A Control Register PACR $80000D

Port B Control Register PBCR $80000F

Port A Data Register PADR $800011

Port B Data Register PBDR $800013

Port C Data Register PCDR $800019



Initializing M68230 Registers

To set the M68230 to device bit I/O mode,the settings are:

Set PGCR to $00.Set PACR and PBCR to $80.

Set PADDR and PBDDR based on datadirection.

For input devices, set bit to 0. For output devices, set bit to 1.



M68230 Initialization

PGCR EQU $800001

PADDR EQU $800005

PBDDR EQU $800007

PCDDR EQU $800009

PACR EQU $80000DPBCR EQU $80000F

PADR EQU $800011

PBDR EQU $800013

PCDR EQU $800019

MOVE.B #$00,PGCRMOVE.B #$80,PACR

MOVE.B #$80,PBCR



Example: LED

PB0

PB1

PB2

PB3

PB4

PB5

PB6

PB7

M68230

MOVE.B #$FF,PBDDR

E l LED & S it h



Example LED & Switches(PADDR = $00, PBDDR = $FF)

PA0 PB0

PA1 PB1

PA2 PB2

PA3 PB3

PA4 PB4

PA5 PB5

PA6 PB6

PA7 PB7

M68230LED0

LED1

LED2

LED3

LED4

LED5

LED6

LED7

+5V

R

R

R

R

R

R

R

R



Example: 7-Segment

B0

B1

B2

B3

B4

B5

B6

B7

a

b

c

d

e

f

g

M68230

MOVE.B #$FF, PBDDR



Example: 7-Segment + BCD

DecoderB0

B1

B2

B3

B4

B5

B6

B7

a

b

c

d

e

f

g

M68230

BCD 7-Seg

Decoder

MOVE.B #$0F,PBDDR



Port X Data Registers (PXDR)

Can either be PADR, PBDR or PCDR.

Contains the data sent/received by the

hardware.



Example: Read Data from Switches



Example: Read Data from Switches(MOVE.B PADR,D0)

PA0 PB0

PA1 PB1

PA2 PB2

PA3 PB3

PA4 PB4

PA5 PB5

PA6 PB6

PA7 PB7

M68230+5V

R

R

R

R

R

R

R

R

If a switch is closed (activated), itwill generate a „1‟ inside the PXDR. In this example, the data fromswitches is stored inside D0 in theM68000 data register.

MOVE.B PADR,D0

Using this command, the valueinside D0 will be:

D0 = $00000000

D0 = $000000C3



7-Segment

Consists of 7-LEDsarranged together.

Can display numbers and

characters. Each segment is marked

with a letter (a to g).

To display characters,

need to turn on/off certainsegments.



Displaying Numbers

b c d e f g Numbera

1 0 0 0 0 0 11

1 0 1 1 0 1 21

1 1 1 0 0 1 31

1 1 0 0 1 1 40

0 1 1 0 1 1 51

0 1 1 1 1 1 60

1 1 0 0 0 0 71

1 1 1 1 1 1 81

1 1 0 0 1 1 91

1 1 1 1 1 0 01



Example: Display 4 on 7-Segment

B0

B1

B2

B3

B4

B5

B6

B7

a

b

c

d

e

f

g

M68230

MOVE.B #$ 66, PBDR

In this example, to display „4‟

on the 7-segment, b, c, e, f,and g must be turned on, andthe rest turned off. This can bedone by sending $66 to the

PBDR.



The 7448 BCD to 7 Segment

Decoder The 7448 decoder can simplify the transfer of

data to the 7-segment.

It converts BCD values directly into thenecessary signals to turn on the 7-segment.

If the decoder is present, there is no need toconsider the values of a-b-c-….-g, just send the

number to be displayed and it is automaticallyshown.



7-Segment + BCD Decoder

B0

B1

B2

B3

B4

B5

B6

B7

a

b

c

d

e

f

g

M68230

BCD 7-Seg

Decoder



Displaying NumbersA3 A2 A1 A0 Number

0 0 0 1 1

0 0 1 0 2

0 0 1 1 3

0 1 0 0 4

0 1 0 1 5

0 1 1 0 6

0 1 1 1 7

1 0 0 0 8

1 0 0 1 9

0 0 0 0 0

a

b

c

d

e

f

g

BCD 7-Seg

Decoder

A3

A2

A1

A0



Sample Programs



Example 1



Example 1: Set LED

PB0

PB1

PB2

PB3

PB4

PB5

PB6

PB7

M68230A set of LEDs are connected toPort B in M68230. Write a programthat turns on LED3 and LED4, andturns off the rest.

LED0

LED1

LED2

LED3

LED4

LED5

LED6

LED7

Port Address

PGCR $800001

PACR $800005

PBCR $800007

PADDR $800009

PBDDR $80000D

PCDDR $80000F

PADR $800011

PBDR $800013

PCDR $800019



Discussion

Port B should be initialized before beingused.

To turn on LED, the voltage at Port B bitsshould be high.

To turn off LED, the voltage at Port B

should be low.



Flowchart



Solution

START ORG $1000

PGCR EQU $800001

PBCR EQU $800007

PBDDR EQU $80000D

PBDR EQU $800013

INIT MOVE.B #$00,PGCR

MOVE.B #$80,PBCR

MOVE.B #$FF,PBDDR

ONLED MOVE.B #%00011000,PBDR

END START



Example 1: Set LED

PB0

PB1

PB2

PB3

PB4

PB5

PB6

PB7

M68230LED0

LED1

LED2

LED3

LED4

LED5

LED6

LED7

0

0

0

1

1

0

0

0



Example 2

E l 2 R d S i h &



Example 2: Read Switches &Output to LED

A set of switches are connected to Port A,and a set of LEDs are connected to Port B

in M68230. Write a program that readsthe value in the switches and turns on therespective LEDs.

Circuit Diagram



Circuit Diagram

PA0 PB0

PA1 PB1

PA2 PB2

PA3 PB3

PA4 PB4

PA5 PB5

PA6 PB6

PA7 PB7

M68230 LED0

LED1

LED2

LED3

LED4

LED5

LED6

LED7

+5V

R

R

R

R

R

R

R

R



Port Assignments

Port Address

PGCR $A00001

PACR $A0000D

PBCR $A0000FPADDR $A00005

PBDDR $A00007

PCDDR $A00009

PADR $A00011

PBDR $A00013

PCDR $A00019



Discussion

Both Port A & B should be initializedbefore being used.

When the switch is ON, 5 V is passed toM68230 (logic 1).

When the switch is OFF, 0 V is passed to

M68230 (logic 0).



Flowchart



Solution – Complete Program

START ORG $1000

PGCR EQU $A00001

PACR EQU $A0000D

PBCR EQU $A0000F

PADDR EQU $A00005

PBDDR EQU $A00007

PADR EQU $A00011

PADR EQU $A00013


MOVE.B #$80,PACR

MOVE.B #$80,PBCR

MOVE.B #$00,PADDR

MOVE.B #$FF,PBDDR

LOOP MOVE.B PADR,D0

MOVE.B D0,PBDR

BRA LOOP

END START

Sample Output



Sample Output

PA0 PB0

PA1 PB1

PA2 PB2

PA3 PB3

PA4 PB4

PA5 PB5

PA6 PB6

PA7 PB7

M68230 LED0

LED1

LED2

LED3

LED4

LED5

LED6

LED7

+5V

R

R

R

R

R

R

R

R



Example 3



Example 1 The M68230 is connected to thehardware shown. Write a program

that turns on all LEDs when bothswitches are closed. Else, turn off allLEDs. The port assignments are shownbelow:

Port Address

PGCR $A00001

PACR $A0000D

PBCR $A0000F

PADDR $A00005

PBDDR $A00007

PCDDR $A00009

PADR $A00011

PBDR $A00013

PCDR $A00019



Flowchart



Program

START ORG $1000

PGCR EQU $A00001

PACR EQU $A0000D

PBCR EQU $A0000F

PADDR EQU $A00005

PBDDR EQU $A00007PADR EQU $A00011

PBDR EQU $A00013


MOVE.B #$80,PACR

MOVE.B #$80,PBCR

MOVE.B #$00,PADDR

MOVE.B #$FF,PBDDR

MOVE.B #$00,PBDR

READSW MOVE.B PADR,D0

AND.B #$C0,D0

CMP.B #$C0,D0

BEQ ONLED

BNE OFFLED

ONLED MOVE.B #$FF,PBDR

BRA HABIS

OFFLED MOVE.B #$00,PBDR

HABIS

END START



Example 4



Example: 7-Segment

A0

A1

A2

A3

A4

A5

A6

A7

a

b

c

d

e

f

g

M68230

Based on the circuit given,display the number “3” on the 7-segment.



Flowchart



Program

PGCR EQU $800001

PADDR EQU $800005

PBDDR EQU $800007

PCDDR EQU $800009

PACR EQU $80000D

PBCR EQU $80000F

PADR EQU $800011PBDR EQU $800013

PCDR EQU $800019

MOVE.B #$00,PGCR

MOVE.B #$80,PACR

MOVE.B #$FF,PADDR

MOVE.B #$79,PADR

END START



Example 5



Example: Displaying „C‟ on 7-Seg

B0

B1

B2

B3

B4

B5

B6

B7

a=1

b=0

c=0

d=1

e=1

f=1

g=0

M68230



Flowchart



Program

START ORG $1000

PGCR EQU $800001

PADDR EQU $800005

PBDDR EQU $800007PCDDR EQU $800009

PACR EQU $80000D

PBCR EQU $80000F

PADR EQU $800011

PBDR EQU $800013

PCDR EQU $800019

MOVE.B #$00,PGCR

MOVE.B #$80,PBCR

MOVE.B #$FF,PBDDR

MOVE.B #$B9,PBDR

END START



Example 6



Example 6The M68230 is connected to thehardware shown. Write a programthat tests the switch at Port A. If the

switch is turned on, display 3 at the7-segment, and turn on the LEDat Port B. The port assignments areshown below:

Port Address

PGCR $800001

PACR $80000D

PBCR $80000F

PADDR $800005

PBDDR $800007

PCDDR $800009

PADR $800011

PBDR $800013

PCDR $800019



Flowchart



Program

START ORG $1000

PGCR EQU $800001

PACR EQU $80000D

PBCR EQU $80000F

PADDR EQU $800005

PBDDR EQU $800007PADR EQU $800011

PBDR EQU $800013


MOVE.B #$80,PACR

MOVE.B #$80,PBCR

MOVE.B #$00,PADDR

MOVE.B #$F1,PBDDR

MOVE.B #$00,PBDR


AND.B #$02,D0

CMP.B #$02,D0

BEQ ON7SEG

BNE OFF7SEG

ON7SEG MOVE.B #$31,PBDR

BRA HABIS

OFF7SEG MOVE.B #$00,PBDR

HABIS

END START



Example 7

Th M68230 i t d t th



Example 7The M68230 is connected to thehardware shown. Write a programthat continuously tests the switches

at Port A and displays the correspondingvalue at the 7-segment. The portassignments are shown below:

Port Address

PGCR $800001

PACR $80000D

PBCR $80000F

PADDR $800005

PBDDR $800007

PCDDR $800009

PADR $800011

PBDR $800013

PCDR $800019



Program

START ORG $1000

PGCR EQU $800001

PACR EQU $80000D

PBCR EQU $80000F

PADDR EQU $800005

PBDDR EQU $800007

PADR EQU $800011PBDR EQU $800013


MOVE.B #$80,PACR

MOVE.B #$80,PBCR

MOVE.B #$00,PADDR

MOVE.B #$0F,PBDDR

ULANG MOVE.B PADR,D0

AND.B #$03,D0

CMP.B #$00,D0

BEQ DISP0

CMP.B #$01,D0

BEQ DISP1

CMP.B #$02,D0

BEQ DISP2

CMP.B #$03,D0

BEQ DISP3

BRA ULANG

DISP0 MOVE.B #$00,PBDR

BRA ULANG


BRA ULANGDISP2 MOVE.B #$02,PBDR

BRA ULANG


BRA ULANG

END START



Example 8



Example

The M68230 is connectedto the circuit shown.Write a program todisplay „10‟ on the

7-segment when theswitch is activated.Else, display „55‟ when

the switch is not activated.



Flowchart



Program

START ORG $1000

PGCR EQU $800001

PACR EQU $80000D

PBCR EQU $80000F

PADDR EQU $800005

PBDDR EQU $800007PADR EQU $800011

PBDR EQU $800013


MOVE.B #$80,PACR

MOVE.B #$80,PBCR

MOVE.B #$00,PADDR

MOVE.B #$FF,PBDDR


AND.B #$01,D0

CMP.B #$00,D0

BEQ DISP55

CMP.B #$01,D0BEQ DISP10

BRA READSW


BRA READSW


BRA READSW

END START



The End

rotate_ conditional and io

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