uPSD3212A, uPSD3212C, uPSD3212CV
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SFR
The SFRs can only be addressed directly in the
address range from 80h to FFh. Table
15., page 28 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
2Eh777675747372717046
2Dh 6F 6E 6D 6C 6B 6A 69 68 45
2Ch676665646362616044
2Bh 5F 5E 5D 5C 5B 5A 59 58 43
2Ah575655545352515042
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