Wire crc generator figure 4 – Rainbow Electronics DS2432 User Manual
Page 4
PRELIMINARY
DS2432
4 of 30
1-WIRE CRC GENERATOR Figure 4
X
0
X
1
X
2
X
3
X
4
X
5
X
6
X
7
X
8
Polynomial = X
8
+ X
5
+ X
4
+ 1
1
st
STAGE
2
nd
STAGE
3
rd
STAGE
4
th
STAGE
6
th
STAGE
5
th
STAGE
7
th
STAGE
8
th
STAGE
INPUT DATA
MEMORY MAP
The DS2432 has four memory areas: data memory, secrets memory, register page with special function
registers and user-bytes, and a scratchpad. The data memory is organized in pages of 32 bytes. Secret,
register page and scratchpad are 8 bytes each. The scratchpad acts as a buffer when writing to the data
memory, loading the initial secret or when writing to the register page.
Data memory, secrets memory and register page are located in a linear address space, as shown in
Figure 5. The data memory and the register page have unrestricted read access. Writing to the data
memory and the register page requires the knowledge of the secret.
DS2432 MEMORY MAP Figure 5
Address Range
Description
Note
0000h to 001Fh
Data Memory Page 0
No write-access without secret
0020h to 003Fh
Data Memory Page 1
No write-access without secret
0040h to 005Fh
Data Memory Page 2
No write-access without secret
0060h to 007Fh
Data Memory Page 3
No write-access without secret
0080h to 0087h
Secrets Memory
No read access; no secret for write access
0088h
1)
Write-protect secret, 008Ch to 008Fh
Protection activated by code AAh or 55h
0089h
1)
Write-protect pages 0 to 3
Protection activated by code AAh or 55h
008Ah
1)
User byte, self-protecting
Protection activated by code AAh or 55h
008Bh
Factory byte (read only)
Reads either AAh or 55h; see text
008Ch
1)
User byte/EPROM mode control for page 1
Mode activated by code AAh or 55h
008Dh
1)
User byte/Write-protect page 0 only
Protection activated by code AAh or 55h
008Eh to 008Fh
User Bytes/Manufacturer ID
Function depends on factory byte
0090h to 0097h
64-Bit Registration Number
(Alternate readout)
1)
Once programmed to AAh or 55h this address becomes read-only. All other codes can be stored but
will neither write-protect the address nor activate any function.