uPSD3212A, uPSD3212C, uPSD3212CV
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SFR
The SFRs can only be addressed directly in the
address range from 80h to FFh.
gives an overview of the Special
Function Registers. Sixteen address in the SFRs
space are both-byte and bit-addressable. The bit-
addressable SFRs are those whose address ends
in 0h and 8h. The bit addresses in this area are
80h to FFh.
Table 3. RAM Address
Addressing Modes
The addressing modes in uPSD321x Devices in-
struction set are as follows
■
Direct addressing
■
Indirect addressing
■
Register addressing
■
Register-specific addressing
■
Immediate constants addressing
■
Indexed addressing
(1) Direct addressing. In a direct addressing the
operand is specified by an 8-bit address field in the
instruction. Only internal Data RAM and SFRs
(80~FFH RAM) can be directly addressed.
Example:
mov A, 3EH ;A <----- RAM[3E]
Figure 11. Direct Addressing
(2) Indirect addressing. In indirect addressing
the instruction specifies a register which contains
the address of the operand. Both internal and ex-
ternal RAM can be indirectly addressed. The ad-
dress register for 8-bit addresses can be R0 or R1
of the selected register bank, or the Stack Pointer.
The address register for 16-bit addresses can only
be the 16-bit “data pointer” register, DPTR.
Example:
mov @R1, #40 H ;[R1] <-----40H
Figure 12. Indirect Addressing
Byte Address
(in Hexadecimal)
Byte Address
(in Decimal)
↓
↓
FFh
255
30h
48
msb
Bit Address (Hex)
lsb
2Fh
7F
7E
7D
7C
7B
7A
79
78
47
2Eh
77
76
75
74
73
72
71
70
46
2Dh
6F
6E
6D
6C
6B
6A
69
68
45
2Ch
67
66
65
64
63
62
61
60
44
2Bh
5F
5E
5D
5C
5B
5A
59
58
43
2Ah
57
56
55
54
53
52
51
50
42
29h
4F
4E
4D
4C
4B
4A
49
48
41
28h
47
46
45
44
43
42
41
40
40
27h
3F
3E
3D
3C
3B
3A
39
38
39
26h
37
36
35
34
33
32
31
30
38
25h
2F
2E
2D
2C
2B
2A
29
28
37
24h
27
26
25
24
23
22
21
20
36
23h
1F
1E
1D
1C
1B
1A
19
18
35
22h
17
16
15
14
13
12
11
10
34
21h
0F
0E
0D
0C
0B
0A
09
08
33
20h
07
06
05
04
03
02
01
00
32
1Fh
Register Bank 3
31
18h
24
17h
Register Bank 2
23
10h
16
0Fh
Register Bank 1
15
08h
8
07h
Register Bank 0
7
00h
0
AI06641
3Eh
Program Memory
04
A
AI06642
R1
55h
Program Memory
55
40h
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