Rainbow Electronics DS2409 - Manual (Page 14)

DS2409
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USAGE EXAMPLE
Configuration: A bus master controls a MicroLAN consisting of a trunk with many DS2409s that create
branches. Each of the DS2409s has a DS2430A connected to its auxiliary output to label its physical
location in the network (see Figure 10). iButton devices are constantly arriving at or departing from the
branches.
Task: Identify one branch where an iButton has arrived and get the branch’s physical location. Determine
the population on that particular branch.
STEP MASTER MODE DATA (LSB FIRST) COMMENTS
1 TX Reset Reset pulse (480µs to 960µs)
2 RX Presence Presence pulse
3 TX ECh Issue “conditional search ROM” command
4 RX/RX/TX for each of the 64 ROM bits Identify and access one of the qualifying devices
5 TX 33h Issue Smart-On Auxiliary command
6 TX FFh Send reset stimulus
7 RX * Get reset response byte with presence info
8 RX 33h Get confirmation byte
9 TX CCh Issue “skip ROM” command
10 TX F0h Issue “read memory” command
11 RX <32 data bytes> Get branch location information (DS2430A)
12 TX Reset Reset pulse
13 RX Presence Presence pulse
14 TX 55h Issue “Match ROM” command
15 TX <8 byte ROM ID> Access the previously identified coupler
16 TX CCh Issue Smart-On Main command
17 TX FFh Send reset stimulus
18 RX * Get reset response byte with presence info
19 RX CCh Get confirmation byte
20 TX F0h Issue “search ROM” command
21 RX/RX/TX for each of the 64 ROM bits Identify one of the devices connected
22 TX Reset Reset pulse
23 RX Presence Presence pulse
24 TX 55h Issue “Match ROM” command
25 TX <8 byte ROM ID> Access the previously identified coupler
26 TX 66h Send all lines off command
27 RX 66h Get confirmation byte
28 TX Reset Reset pulse
29 RX Presence Presence pulse
repeat steps 12 to 21 for each of the remaining devices on the branch of the identified coupler
* 00h or 01h if presence pulse, FFh if no presence pulse
NOTE:
The sequence of steps 12 to 21 logically decouples all other devices residing on the trunk from
responding to the search ROM command. The All Lines Off command is required to clear the event flag
that made the device respond to the conditional search command.