ME4447/6405
ME 4447/6405
Microprocessor Control of Manufacturing Systems
and
Introduction to Mechatronics
Instructor: Professor Charles Ume
Lecture #11
George W. Woodruff School of Mechanical Engineering, Georgia Tech
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MON12 Utility Subroutines
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
MON12 Utility Subroutines
MON12 Utility Subroutines
• Subroutines are available for performing I/O tasks.
• Jump table has been set up in EEPROM beneath
interrupt vectors.
• To use these jump subroutines, execute jump to
subroutine (JSR) command to appropriate entry in
jump table.
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
UPCASE
Subroutine Listing
If character in accumulator A is lower case alpha, convert to
upper case.
WCHEK
Test character in accumulator A and return with Z bit set if
character is whitespace (space, comma, tab).
DCHEK
Test character in accumulator A and return with Z bit set if
character is delimiter (carriage return or whitespace).
ONSCIO
Initialize I/O device.
INPUT
Read I/O device.
OUTPUT
Write I/O device.
OUTLHLF
Convert left nibble of accumulator A contents to
ASCII and output to terminal port.
OUTRHLF
Convert right nibble of accumulator A contents to
ASCII and output to terminal port.
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
OUTA
OUT1BYT
Subroutine Listing Cont’d
Output accumulator A ASCII character.
Convert binary byte at address in index register X to two ASCII
characters and output. Return address in index register X pointing to
next byte.
OUT1BSP Convert binary byte at address in index register X to two ASCII
characters and output followed by a space. Returns address in index
register.
OUT2BSP Convert two consecutive binary bytes starting at address in index X to
four ASCII characters and output followed by a space. Returns address
in index register X pointing to next byte.
OUTCCRLF Output ASCII carriage return followed by a line feed.
OUTSTRG Output string of ASCII bytes pointed to by address in index register X
until character is an end of transmission ($04).
OUTSTRGO Same as OUTSTRG except leading carriage return and line feed is
skipped.
INCHAR
Waits for you to type an ASCII character from the keyboard, and stores
the corresponding
ASCII number
in accumulator
George W. Woodruff
School of Mechanical
Engineering,
Georgia TechA, and then
outputs the ASCII character to the screen.
ME4447/6405
To use an I/O subroutine, Jump Sub Routine (JSR) to the specified address
listed below.
ADDRESS
SUBROUTINE
FUNCTION
•
•
•
•
•
•
•
•
•
•
•
$FF37
$FF3A
$FF3D
$FF40
$FF43
$FF46
$FF49
$FF4C
$FF4F
$FF52
$FF55
UPCASE
WCHEK
DCHEK
ONSCIO
INPUT
OUTPUT
OUTLHLF
OUTRHLF
OUTA
OUTlBYT
OUT1BSP
•
$FF58
OUT2BSP
•
•
•
$FF5B
$FF5E
$FF61
OUTCRLF
OUTSTRG
OUTSTRGO
•
$FF64
Convert character to uppercase
Test character for whitespace
Check character for delimiter
Initialize I/O device
Read I/O device
Write I/O device
Convert left nibble to ASCII and output
Convert right nibble to ASCII and output
Output ASCII character
Convert binary byte to 2 ASCII characters and output
Convert binary byte to 2 ASCII characters and output
followed by space
Convert 2 consecutive binary bytes to 4 ASCII
characters and output followed by space.
Output ASCII carriage return followed by line feed
Output ASCII string until end of transmission ($04)
Same as OUTSTRG except leading carriage return
and line feed is skipped
Input ASCII character and echo back
INCHAR
George W.
Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: OUTA
ORG $1000
LDAA #$41
*Load acc. A with ASCII code for the
*character A.
JSR $FF4F
*JSR to the subroutine OUTA
SWI
END
Result A is written to the screen.
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: OUTSTRG (Output ASCII Character String until EOT, $04, is encountered)
STR1
EQU $2100
OUTSTRG EQU $FF5E
ORG STR1
FCC “ABCDEFG”
FCB #$04
ORG $1000
LDX #STR1
JSR OUTSTRG
*Go to OUTSTRG routine which
*outputs ASCII characters contained in each
*address starting from $2100 until
*an EOT character is found.
SWI
END
ResultABCDEFG written to the screen on a new line.
(Note: ASCII end of transmission (EOT) character must be used with the
OUTSTRG
subroutine
let it of
know
when to Engineering,
stop readingGeorgia
from Tech
George W.
Woodruff to
School
Mechanical
memory. EOT ASCII = #$04)
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Difference Between the Utility Subroutines OUTSTRG and
OUTSTRG0
Assume you want to print the following to the screen:
MEMORY LOCATION $_____CONTAINS _____ IN DECIMAL.
Use subroutine OUTSTRG to print “MEMORY LOCATION $” to screen on
a new line (It always starts printing on a new line, because it outputs
carriage return with line feed).
Use subroutine OUTSTRG0 to print “CONTAINS” to screen on same line
as “MEMORY LOCATION $” (Because it does not output carriage return
with line feed)
Use subroutine OUTSTRG0 to print “IN DECIMAL.” to screen on the
same line
(Note: Refer to Lab website for example program to print
decimal numbers to the screen.)
George W. Woodruff School of Mechanical Engineering, Georgia Tech
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Utility Subroutines Examples
Example: OUTLHLF (Out Left Half) and OUTRHLF (Out Right Half)
ORG $1000
LDAA #$AF
JSR $FF49
LDAA #$AF
JSR $FF4C
*Puts hex number $AF in acc. A
*Goes to subroutine OUTLHLF which converts left
*nibble, #$A, to ASCII number, $41, and then outputs
*its ASCII character, ‘A, to the screen.
*Reload Acc. A since OUTLHLF modifies the contents of
*Acc. A
*Goes to subroutine OUTRHLF which converts right
*nibble, #$F, to ASCII number, $46, and then outputs
*its ASCII character, ‘F, to the screen.
SWI
END
Result  AF is written to the screen.
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: OUT1BYT (Out 1 Byte) and OUT1BSP (Out 1 Byte with Space)
Assume that memory contains the following:
2100 FA FB
Now execute the following code:
ORG $1000
LDX #$2100
JSR $FF52
*Goes to subroutine OUT1BYT which converts the
*content of the address pointed to by the X register to
*two ASCII equivalents and outputs their characters to
*the screen, and increments X register by #$1.
JSR $FF55
*Goes to subroutine OUT1BSP which converts the
*content of the address pointed to by the X register to
*two ASCII equivalents and outputs their characters to the
*screen followed by a space.
SWI
END
Result FAFB_ sent to screen (Note: last character is a space)
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: OUT2BSP (Out 2 Bytes with Space)
Assume that memory contains the following:
2100 FA FB
Now execute the following code.
ORG $1000
LDX #$2100
JSR $FF58
*JSR to subroutine OUT2BSP which converts two
*consecutive binary bytes to their 4 ASCII numbers
*and outputs their ASCII characters to the screen followed by a
*space.
SWI
END
ResultFAFB_ sent to screen (last character is a space).
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: OUTCRLF (Output Carriage Return with Line Feed)
ORG $1000
JSR $FF5B
*Go to subroutine OUTCRLF
*which outputs ASCII carriage return
*followed by a line feed.
SWI
END
Result New line on screen (Note:Equivalent to pressing
Enter in your computer)
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Utility Subroutines Examples
Example: INCHAR (Input Character)
ORG $1000
JSR $FF64
*Goes to subroutine INCHAR. Waits for you to
*type an ASCII character from the keyboard,
*and stores the corresponding ASCII number in
*accumulator A
SWI
END
Result-> If you type 9 on the keyboard, ASCII number
$39 is stored in accumulator A
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
Example
Write an assembly language program to output a string of characters to the screen.
Solution: This particular solution will print “Hello” to the screen using the OUTA
subroutine
OUTA
Loop
Quit
EQU
$FF4F
ORG
FCC
FCB
$2000
“HELLO”
#$04
ORG
LDX
LDAA
CMPA
BEQ
JSR
INX
BRA
SWI
END
$1000
#$2000
$00,X
#$04
Quit
OUTA
FCC is used to store a string of
characters
FCB is used to store End Of
Transmission (EOT)
(Note 1: EOT in ASCII is $04)
(Note 2: In this particular example
any non-printing character can be
used)
Loop
George W. Woodruff School of Mechanical Engineering, Georgia Tech
Program
Skip
Ahead
Initialization
Until Last Loop
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CPU Registers Used in Program:
#$48
#$6F
#$04
#$65
Accum A:
#$2002
#$2001
#$2000
Index X: #$2005
CCR Bit Z:
0
1
OUTA
EQU
$FF4F
ORG
FCC
CCRZ Zis is
1 since FCB
CCR
0 since
AccumA A
equals
Accum
does
not
equal $04
$04
ORG
$2000
“Hello”
#$04
Loop
Memory Locations Used in Program:
$2000
$48
$2001
$65
$2002
$6C
$2003
$6C
$2004
LDX
LDAA
CMPA
BEQ
JSR
INX
BRA
SWI
END
$1000
#$2000
$00,X
#$04
Quit
OUTA
Loop
Does
notsince
Branch
branch
CCR Z is 1
because CCR
Always
Z is 0 Branches
Quit
Ascii
Equivalent
of “Hello”
Computer Screen:
He llo
$6F
$2005
$04Woodruff School of Mechanical Engineering, Georgia Tech
George W.
ME4447/6405
Solution 2: This particular solution will print “Hello” to the screen using the
OUTSTRG subroutine
OUTSTRG
EQU
$FF5E
ORG
FCC
FCB
$2000
“HELLO”
#$04
ORG
LDX
JSR
SWI
END
$1000
#$2000
OUTSTRG
(Note: EOT must be used because
the OUTSTRG Subroutine uses
EOT as the end of the string)
OUTSTRG: Output ASCII string until
end of transmission ($04)
George W. Woodruff School of Mechanical Engineering, Georgia Tech
ME4447/6405
QUESTIONS???
George W. Woodruff School of Mechanical Engineering, Georgia Tech