DS2408 Maxim, DS2408 Datasheet - Page 33

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

Channel-Access Write (Success)
Channel-Access Write (Fail New State)
Write Conditional Search Register (Success)
Write Conditional Search Register (Fail Address)
Reset Activity Latches (Cannot Fail)
COMMUNICATION EXAMPLES
The examples in this section demonstrate the use of ROM and control functions in typical situations. The
first two examples are related to Figure 17. They show how to write to the PIO with readback for
verification or for receiving an immediate response (example 1) and how to read from the PIO in an
endless loop (example 2). The third example assumes a network of multiple DS2408s where each of the
devices is connected to 8 pushbuttons, as in Figure 21.
Example 1
Task: Write to the PIO with readback for verification or for receiving an immediate response.
This task is broken into the following steps:
1) Configure RSTZ as
2) Verify configuration setting.
3) Write to the PIO and read back the response.
With only a single DS2408 connected to the bus master, the communication is as follows:
Step 1
RST
RST
RST
RST
RST
MASTER MODE
PD
PD
PD
PD
PD
TX
RX
TX
TX
TX
TX
TX
Select
Select
Select
Select
Select
STRB
CAW
CAW
WCS
WCS
RAL
output.
<new state>, <new state\>
<new state>, <invalid>
TA
TA
AA loop
DATA (LSB FIRST)
(Presence)
<data>
FF loop
(Reset)
CCh
CCh
8Dh
00h
04h
FF loop
33 of 39
FF loop
AAh, <read back>
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Write Conditional Search Register
command
TA1, target address = 8Dh
TA2, target address = 008Dh
Write byte to Control/Status Register
COMMENTS
Loop
DS2408