DS2408 Maxim, DS2408 Datasheet - Page 8

• Manufacturer Part Number: DS2408
• Description: The DS2408 is an 8-channel, programmable I/O 1-Wire® chip
• Manufacturer: Maxim

The shift register bits are initialized to 0. Then, starting with the least significant bit of the family code,
one bit at a time is shifted in. After the eighth bit of the family code has been entered, the serial number is
entered. After the serial number has been entered, the shift register contains the CRC value. Shifting in
the eight bits of CRC returns the shift register to all 0s.
Figure 4. 1-Wire CRC GENERATOR
REGISTER ACCESS
The registers needed to operate the DS2408 are organized as a Register Page, as shown in Figure 5. All
registers are volatile, i. e., they lose their state when the device is powered down. PIO, Conditional
Search, and Control/Status registers are read/written using the device level Read PIO Registers and Write
Conditional Search Register commands described in subsequent sections and Figure 8 of this document.
Figure 5. DS2408 REGISTER ADDRESS MAP
X
ADDRESS RANGE
0000h to 0087h
0088h
0089h
008Ah
008Bh
008Ch
008Dh
008Eh to 008Fh
0
STAGE
1
st
X
1
STAGE
2
nd
X
2
STAGE
3
rd
ACCESS TYPE
X
3
R/W
R/W
R/W
STAGE
R
R
R
R
R
POLYNOMIAL = X
4
th
DESCRIPTION
Undefined Data
PIO Logic State
PIO Output Latch State Register
PIO Activity Latch State Register
Conditional Search Channel Selection Mask
Conditional Search Channel Polarity Selection
Control/Status Register
These Bytes Always Read FFh
8 of 39
8
X
+ X
4
STAGE
5
5
th
+ X
4
+ 1
X
5
STAGE
6
th
INPUT DATA
X
6
STAGE
7
th
X
7
STAGE
8
th
X
DS2408
8