DS2408 Maxim, DS2408 Datasheet - Page 34

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

When using this communication example to send data to a remote microcontroller, as in Figure 17,
synchronization between the master and the remote microcontroller can be maintained by transmitting
data packets that begin with a length byte and end with a CRC16. See Application Note 114, section
"UNIVERSAL DATA PACKET" for details.
Example 2
Task: Read from the PIO in an endless loop.
This task is broken into the following steps:
1) Configure RSTZ as
2) Verify configuration setting.
3) Read from the PIO.
With only a single DS2408 connected to the bus master, the communication is as follows:
Step 2
Step 3
Step 1
MASTER MODE
MASTER MODE
(—)
(—)
(—)
TX
TX
TX
RX
RX
RX
RX
RX
RX
RX
RX
RX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
TX
STRB
output.
<inverted PIO output byte>
<inverted PIO output byte>
<PIO pin status byte>
<PIO pin status byte>
DATA (LSB FIRST)
DATA (LSB FIRST)
<PIO output byte>
<PIO output byte>
(Presence)
(Presence)
(Presence)
(Presence)
(Reset)
(Reset)
(Reset)
(Reset)
CCh
CCh
CCh
CCh
AAh
AAh
8Dh
5Ah
8Dh
F0h
00h
84h
(—)
(—)
(—)
00h
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Reset pulse
Presence pulse
Issue Skip ROM command
Issue Read PIO Registers command
TA1, target address = 8Dh
TA2, target address = 008Dh
Read Control/Status Register and verify
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Channel-access Write command
Write byte to PIO
Write inverted byte to PIO
DS2408 updates PIO status if transmission
was OK
Read for verification (AAh = success)
DS2408 samples PIO pin status
Read PIO pin status
Write byte to PIO (next byte)
Write inverted byte to PIO (next byte)
Read for verification (AAh = success)
Read PIO pin status
Repeat the previous 4 steps with more PIO
output data as needed in the application.
Reset pulse
Presence pulse
Reset pulse
Presence pulse
Issue Skip ROM command
Issue Write Conditional Search Register
command
TA1, target address = 8Dh
TA2, target address = 008Dh
COMMENTS
COMMENTS
DS2408