DS2408S+ Maxim Integrated Products, DS2408S+ Datasheet - Page 34

• Manufacturer Part Number: DS2408S+
• Description: PROM 1-Wire 8-Ch Addressable Switch
• Manufacturer: Maxim Integrated Products

Specifications of DS2408S+

• Lead Free Status / Rohs Status: Details

When using this communication example to read data from a remote microcontroller, as in Figure 17,
synchronization between the remote microcontroller and the master 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 3
Task: Detect the specific DS2408 where the button was pressed and identify the pin to which the
pushbutton is connected. This task is broken into the following steps:
1) Configure the conditional search and verify configuration setting.
2) Switch off all channel output transistors.
3) Clear the activity latches.
4) Search until a pushbutton is pressed.
5) Identify device and pushbutton; reset activity latches.
The device has to respond to the conditional search if the activity latch of at least one of the 8 channels is
set. This requires the following setup data for the conditional search registers:
Step 2
Step 3
Channel Selection Mask, select all channels Þ FFh
Channel Polarity Selection, select logic 1 for all channels Þ FFh
MASTER MODE
(—)
(—)
(—)
TX
TX
RX
RX
RX
RX
RX
RX
TX
TX
TX
TX
TX
TX
TX
TX
<PIO pin status byte>
DATA (LSB FIRST)
<2 bytes CRC16>
(Presence)
(Presence)
(Presence)
(Reset)
(Reset)
(Reset)
CCh
CCh
8Dh
04h
F0h
00h
84h
F5h
(—)
(—)
(—)
34 of 36
Write byte to Control/Status Register
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 Read command
DS2408 samples PIO pin status
Read PIO pin status
Repeat the previous 2 steps until the master
has received a total of 32 bytes of PIO pin
status
Read CRC16
PIO pin status and CRC loop can be
continued as long as the application requires.
Reset pulse
Presence pulse
COMMENTS