Datasheet

DS2408
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Channel-Access Write (Success)
RST PD Select CAW <new state>, <new state\> AAh, <read back>
Channel-Access Write (Fail New State)
RST PD Select CAW <new state>, <invalid> FF loop
Write Conditional Search Register (Success)
RST PD Select WCS TA <data> FF loop
Write Conditional Search Register (Fail Address)
RST PD Select WCS TA FF loop
Reset Activity Latches (Cannot Fail)
RST PD Select RAL AA loop
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
STRB
output.
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:
MASTER MODE DATA (LSB FIRST) COMMENTS
Step 1 TX
(Reset)
Reset pulse
RX (Presence) Presence pulse
TX CCh Issue Skip ROM command
TX CCh Issue Write Conditional Search Register
command
TX 8Dh TA1, target address = 8Dh
TX 00h TA2, target address = 008Dh
TX 04h Write byte to Control/Status Register
Loop