MSM9225B User’s Manual
Chapter 2 Register Descriptions
2 – 1
Chapter 2
Register Descriptions
2.1
Memory Space
The MSM9225B has 256 bytes of memory space for the message memory and control registers. Before starting
communication, messages for communication and various control registers must be set.
Figure 2-1 shows the configuration of memory space.
The message memory and the control registers are selected by an 8-bit address.
The message memory consists of 16 message boxes (message box 0 to message box F). Each message box is
selected by the high-order 4 bits (0hex to Fhex) of the address, and the message control register, the identifier,
and the area for storing the message contents are selected by the low-order 4 bits (0hex to Dhex) of the address.
It is possible to store a 2-byte (standard format) or a 5-byte (extended format) identifier and a message of a
maximum of 8 bytes can be stored in each message box. The control registers are selected by the low-order 4
bits (Ehex, Fhex) of the address. Table 2-1 shows the configuration of the control registers.
Figure 2-1 Memory Space Configuration
Message memory
Control registers
H(hex)
L(hex)
Lower
addresses
0 to D
E
F
Higher addresses 0 to F
Message control register (MCR)
Identifier 0 (IDR0)
0
1
2
3
4
5
6
7
8
9
A
B
C
D
H(hex)
L(hex)
Standard format
Message boxes specified by high-order 4 bits of addresses
“H” indicates high-order 4 bits and
“L” indicates low-order 4 bits.
Identifier 1 (IDR1)
Not used
Message 0 (MSG0)
Identifier 2 (IDR2)
Extended format
Message 1 (MSG1)
Message 2 (MSG2)
Message 3 (MSG3)
Message 4 (MSG4)
Message 5 (MSG5)
Message 6 (MSG6)
Message 7 (MSG7)
Not used
Not used
Identifier 3 (IDR3)
Identifier 4 (IDR4)
Message 0 (TMSG0)
Message 1 (TMSG1)
Message 2 (TMSG2)
Message 3 (TMSG3)
Message 4 (TMSG4)
Message 5 (TMSG5)
Message 6 (TMSG6)
Message 7 (TMSG7)
Содержание MSM9225B
Страница 7: ...Chapter 1 Overview...
Страница 13: ...Chapter 2 Register Descriptions...
Страница 53: ...Chapter 3 Operational Description...
Страница 62: ...Chapter 4 Microcontroller Interface...
Страница 71: ...Chapter 5 Electrical Characteristics...
Страница 81: ...Appendixes...