ade7566 Analog Devices, Inc., ade7566 Datasheet - Page 74

• Manufacturer Part Number: ade7566
• Description: Single-phase Energy Measurement Ic With 8052 Mcu, Rtc, And Lcd Driver
• Manufacturer: Analog Devices, Inc.

ADE7566/ADE7569
Address 0x80 through Address 0xFF of general-purpose RAM
are shared with the special function registers. The mode of
addressing determines which memory space is accessed as
shown in Figure 78.
Both direct and indirect addressing can be used to access general-
purpose RAM from 0x00 through 0x7F. However, only indirect
addressing can be used to access general-purpose RAM from
0x80 through 0xFF because this address space shares the same
space with the special function registers (SFRs).
The 8052 core also has the means to access individual bits of
certain addresses in the general-purpose RAM and special
function memory spaces. The individual bits of general-purpose
RAM Address 0x20 to Address 0x2F can be accessed through
their Bit Address 0x00 through Bit Address 0x7F. The benefit of
bit addressing is that the individual bits can be accessed quickly
without the need for bit masking, which takes more code memory
and execution time. The bit addresses for general-purpose RAM
Address 0x20 through Address 0x2F can be seen in Figure 79.
Bit addressing can be used for instructions that involve Boolean
variable manipulation and program branching (see the
Instruction Set section).
Special Function Registers
Special function registers are registers that affect the function of
the 8052 core or its peripherals. These registers are located in
RAM in Address 0x80 through Address 0xFF. They are only
accessible through direct addressing as shown in Figure 78.
Figure 78. General-Purpose RAM and SFR Memory Address Overlap
0xFF
0x7F
0x80
0x00
Figure 79. Bit Addressable Area of General-Purpose RAM
ADDRESS
0x2E
0x2D
0x2C
0x2B
0x2A
0x2F
0x29
0x28
0x27
0x26
0x25
0x24
0x23
0x22
0x21
0x20
INDIRECT ADDRESSING
BYTE
DIRECT AND INDIRECT
ACCESSIBLE BY
ACCESSIBLE BY
GENERAL-PURPOSE RAM
SPECIAL FUNCTION REGISTERS (SFRs)
ADDRESSING
7F
6F
5F
4F
3F
2F
1F
0F
77
67
57
47
37
27
17
07
ONLY
7E
6E
5E
4E
3E
2E
1E
0E
76
66
56
46
36
26
16
06
BIT ADDRESSES (HEXA)
7D
6D
5D
4D
3D
2D
1D
0D
75
65
55
45
35
25
15
05
7C
6C
5C
4C
3C
2C
1C
0C
74
64
54
44
34
24
14
04
DIRECT ADDRESSING
7B
6B
5B
4B
3B
2B
1B
0B
73
63
53
43
33
23
13
03
ACCESSIBLE BY
7A
6A
5A
4A
3A
2A
1A
0A
72
62
52
42
32
22
12
02
ONLY
79
71
69
61
59
51
49
41
39
31
29
21
19
11
09
01
78
70
68
60
58
50
48
40
38
30
28
20
18
10
08
00
Rev. 0 | Page 74 of 136
The individual bits of some SFRs can be accessed for use in
Boolean and program branching instructions. These SFRs are
labeled as bit-addressable and the bit addresses are given in the
SFR Mapping section.
Extended Internal RAM (XRAM)
The ADE7566/ADE7569 provide 256 bytes of extended on-chip
RAM. No external RAM is supported. This RAM is located in
Address 0x0000 through Address 0x00FF in the extended RAM
space. To select the extended RAM memory space, the extended
indirect addressing modes are used. The internal XRAM is
enabled in the Configuration SFR (CFG, 0xAF) by writing 01 to
CFG[1:0].
Code Memory
Code and data memory are stored in the 16 kB flash memory
space. No external code memory is supported. To access code
memory, code indirect addressing is used.
ADDRESSING MODES
The 8052 core provides several addressing modes. The
addressing mode determines how the core interprets the
memory location or data value specified in assembly language
code. There are six addressing modes as shown in Table 62.
Table 62. 8052 Addressing Modes
Addressing Mode
Immediate
Direct
Indirect
Extended Direct
Extended Indirect
Code Indirect
Immediate Addressing
In immediate addressing, the expression entered after the
number sign (#) is evaluated by the assembler and stored in the
specified memory address. This number is referred to as a literal
because it refers only to a value and not to a memory location.
Instructions using this addressing mode is slower than those
between two registers because the literal must be stored and
fetched from memory. The expression can be entered as a
symbolic variable or an arithmetic expression; the value is
computed by the assembler.
Figure 80. Extended Internal RAM (XRAM) Space
0x00FF
0x0000
Example
MOV A,#A8h
MOV DPTR,#A8h
MOV A,A8h
MOV A,IE
MOV A,R0
MOV A,@R0
MOVX A,@DPTR
MOVX A,@R0
MOVC A,@A+DPTR
MOVC A,@A+PC
JMP @A+DPTR
EXTENDED INTERNAL
256 BYTES OF
RAM (XRAM)
Bytes
2
3
2
2
1
1
1
1
1
1
1
Core Clock
Cycles
2
3
2
2
1
2
4
4
4
4
3