8XC251SA, SB, SP, SQ USER’S MANUAL
A-58
Example:
The on-chip RAM locations 40H, 50H, and 60H contain 01H, 70H, and 15H, respectively.
After executing the following instruction sequence
DJNZ 40H,LABEL1
DJNZ 50H,LABEL2
DJNZ 60H,LABEL
on-chip RAM locations 40H, 50H, and 60H contain 00H, 6FH, and 14H, respectively, and
program execution continues at label LABEL2. (The first jump was not taken because the
result was zero.)
This instruction provides a simple way of executing a program loop a given number of times,
or for adding a moderate time delay (from 2 to 512 machine cycles) with a single instruction.
The instruction sequence,
toggles P1.7 eight times, causing four output pulses to appear at bit 7 of output Port 1. Each
pulse lasts three states: two for DJNZ and one to alter the pin.
Variations
DJNZ dir8,rel
Binary Mode
Source Mode
Not Taken
Taken
Not Taken
Taken
Bytes:
3
3
3
3
States:
3
6
3
6
Hex Code in:
Binary Mode = [Encoding]
Source Mode = [Encoding]
Operation:
DJNZ
(PC)
←
(PC) + 2
(dir8)
←
(dir8) – 1
IF (dir8) > 0 or (dir8) < 0
THEN
(PC)
←
(PC) + rel
DJNZ Rn,rel
Binary Mode
Source Mode
Not Taken
Taken
Not Taken
Taken
Bytes:
2
2
3
3
States:
2 5
3
6
Hex Code in:
Binary Mode = [Encoding]
Source Mode = [A5][Encoding]
TOGGLE:
MOV R2,#8
CPL P1.7
DJNZ R2,TOGGLE
[Encoding]
1 1 0 1
0 1 0 1
direct addr
rel. addr
[Encoding]
1 1 0 1
1 r r r
rel. addr
Содержание 8XC251SA
Страница 2: ......
Страница 3: ...May 1996 8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual...
Страница 18: ......
Страница 19: ...1 Guide to This Manual...
Страница 20: ......
Страница 30: ......
Страница 31: ...2 Architectural Overview...
Страница 32: ......
Страница 41: ...3 Address Spaces...
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Страница 63: ...4 Device Configuration...
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Страница 81: ...5 Programming...
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Страница 102: ......
Страница 103: ...6 Interrupt System...
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Страница 121: ...7 Input Output Ports...
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Страница 133: ...8 Timer Counters and Watchdog Timer...
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Страница 153: ...9 Programmable Counter Array...
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Страница 171: ...10 Serial I O Port...
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Страница 187: ...11 Minimum Hardware Setup...
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Страница 197: ...12 Special Operating Modes...
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Страница 207: ...13 External Memory Interface...
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Страница 239: ...14 Programming and Verifying Nonvolatile Memory...
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Страница 250: ......
Страница 251: ...A Instruction Set Reference...
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Страница 391: ...B Signal Descriptions...
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Страница 401: ...C Registers...
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Страница 437: ...Glossary...
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Страница 447: ...Index...
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