ST7SCR_07 Datasheet, PDF (72/101 Pages) STMicroelectronics – 8-BIT LOW-POWER, FULL-SPEED USB MCU WITH 16K FLASH, 768 RAM, SMARTCARD I/F, TIMER

ST7SCR
13 INSTRUCTION SET
13.1 CPU ADDRESSING MODES
The CPU features 17 different addressing modes
which can be classified in 7 main groups:
Addressing Mode
Inherent
Immediate
Direct
Indexed
Indirect
Relative
Bit operation
Example
nop
ld A,#$55
ld A,$55
ld A,($55,X)
ld A,([$55],X)
jrne loop
bset byte,#5
The CPU Instruction set is designed to minimize
the number of bytes required per instruction: To do
so, most of the addressing modes may be subdi-
vided in two sub-modes called long and short:
– Long addressing mode is more powerful be-
cause it can use the full 64 Kbyte address space,
however it uses more bytes and more CPU cy-
cles.
– Short addressing mode is less powerful because
it can generally only access page zero (0000h -
00FFh range), but the instruction size is more
compact, and faster. All memory to memory in-
structions use short addressing modes only
(CLR, CPL, NEG, BSET, BRES, BTJT, BTJF,
INC, DEC, RLC, RRC, SLL, SRL, SRA, SWAP)
The ST7 Assembler optimizes the use of long and
short addressing modes.
Table 22. CPU Addressing Mode Overview
Inherent
Mode
Syntax
nop
Destination
Pointer
Address
(Hex.)
Pointer Size
(Hex.)
Length
(Bytes)
+0
Immediate
ld A,#$55
+1
Short
Direct
ld A,$10
00..FF
+1
Long
Direct
ld A,$1000
0000..FFFF
+2
No Offset Direct Indexed ld A,(X)
00..FF
+0
Short
Direct Indexed ld A,($10,X)
00..1FE
+1
Long
Direct Indexed ld A,($1000,X)
0000..FFFF
+2
Short
Indirect
ld A,[$10]
00..FF
00..FF
byte
+2
Long
Indirect
ld A,[$10.w]
0000..FFFF 00..FF
word
+2
Short
Indirect Indexed ld A,([$10],X)
00..1FE
00..FF
byte
+2
Long
Indirect Indexed ld A,([$10.w],X) 0000..FFFF 00..FF
word
+2
Relative
Direct
jrne loop
PC+/-127
+1
Relative
Indirect
jrne [$10]
PC+/-127 00..FF
byte
+2
Bit
Direct
bset $10,#7
00..FF
+1
Bit
Indirect
bset [$10],#7
00..FF
00..FF
byte
+2
Bit
Direct Relative btjt $10,#7,skip 00..FF
+2
Bit
Indirect Relative btjt [$10],#7,skip 00..FF
00..FF
byte
+3
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