NAME

DS2409 - MicroLAN Coupler

SYNOPSIS

1-wire network branch controller.

FAMILY CODE

SPECIAL PROPERTIES

aux

directory
This is the aux branch of the DS2409 network branch. It is implicitly accessed (via the aux smart-on command) when it is listed or devices on this branch are addressed.

branch.0 branch.1 branch.ALL branch.BYTE

read-write, yes-no
Writing a value of 1 to the branch properties explicitly selects the meant branch ( 0=main or 1=aux ). Writing 0 deselects the branch. This is an addition to the directory branch selection scheme available by simply accessing the main and aux directories. Both ways to select a branch coexist nicely but the latest scheme used wins. Attempting to select both branches, either by setting both bits at the same time or subsequently, fails. Clearing both branch selection bits, either by clearing both bits at the same time or subsequently, resets the event flags inside the DS2409 as a side effect. Reading the branch properties returns which branch (if any) is connected to the master bus.

After using the directory branch selection scheme, both branches are deselected automatically.

ALL is an aggregate of the properties, comma separated. It is an atomic operation.
BYTE is an aggregate of the branches as a byte, main is bit 0. It is an atomic operation.

control

read-write, unsigned integer
Setting of the PIO control pin. There are 4 possible settings:

0: Unconditionally off (non-conducting)
1: Unconditionally on (conducting)
2: Auto on when main branch switched in
3: Auto on when aux branch switched in

discharge

write-only, yes-no
Writing a non-zero value to this property will electrically reset both the main and auxiliary branches of the 1-wire bus by dropping power for 100 milliseconds. All devices on those branches will lose parasitic power and reset to power-up defaults. As a side effect, both event flags and thus, the alarm state, are cleared, too.

event.0 event.1 event.ALL event.BYTE

read-only, yes-no
Has the event flag for the branch been triggered? A negative edge on the disconnected branch ( 0=main or 1=aux ) sets the flag. This is achieved by e.g. connecting an iButton to the branch. Value returned is 1 (yes) or 0 (no).

After accessing the main or aux directory, both branches are deselected automatically and thus, the event flags and alarm state are cleared.

ALL is an aggregate of the properties, comma separated. It is an atomic operation.
BYTE is an aggregate of the branches as a byte, main is bit 0. It is an atomic operation.

clearevent

write-only, yes-no
Writing a non-zero value to this property will reset both event flags and thus, clear the alarm state, too.

main

directory
This is the main branch of the DS2409 network branch. It is implicitly accessed (via the main smart-on command) when it is listed or devices on this branch are addressed.

sensed.0 sensed.1 sensed.ALL sensed.BYTE

read-only, yes-no
Voltage sensed at the 0=main or 1=aux branch pin. Valid only when the branch is switched out. Value returned is 0 (low) or 1 (high).

ALL is an aggregate of the properties, comma separated. It is an atomic operation.
BYTE is an aggregate of the branches as a byte, main is bit 0. It is an atomic operation.

STANDARD PROPERTIES

address

r_address

read-only, ascii
The entire 64-bit unique ID. Given as upper case hexadecimal digits (0-9A-F).
address starts with the family code
r address is the address in reverse order, which is often used in other applications and labeling.

crc8

read-only, ascii
The 8-bit error correction portion. Uses cyclic redundancy check. Computed from the preceding 56 bits of the unique ID number. Given as upper case hexadecimal digits (0-9A-F).

family

read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexadecimal digits (0-9A-F).

id

r_id

read-only, ascii
The 48-bit middle portion of the unique ID number. Does not include the family code or CRC. Given as upper case hexadecimal digits (0-9A-F).
r id is the id in reverse order, which is often used in other applications and labeling.

locator

r_locator

read-only, ascii
Uses an extension of the 1-wire design from iButtonLink company that associated 1-wire physical connections with a unique 1-wire code. If the connection is behind a Link Locator the locator will show a unique 8-byte number (16 character hexadecimal) starting with family code FE.
If no Link Locator is between the device and the master, the locator field will be all FF.
r locator is the locator in reverse order.

present (DEPRECATED)

read-only, yes-no
Is the device currently present on the 1-wire bus?

type

read-only, ascii
Part name assigned by Dallas Semi. E.g. DS2401 Alternative packaging (iButton vs chip) will not be distiguished.

ALARMS

The DS2409 will respond to a conditional search if the main event flag is set.

DESCRIPTION

1-Wire

1-wire is a wiring protocol and series of devices designed and manufactured by Dallas Semiconductor, Inc. The bus is a low-power low-speed low-connector scheme where the data line can also provide power.

Each device is uniquely and unalterably numbered during manufacture. There are a wide variety of devices, including memory, sensors (humidity, temperature, voltage, contact, current), switches, timers and data loggers. More complex devices (like thermocouple sensors) can be built with these basic devices. There are also 1-wire devices that have encryption included.

The 1-wire scheme uses a single bus master and multiple slaves on the same wire. The bus master initiates all communication. The slaves can be individually discovered and addressed using their unique ID.

Bus masters come in a variety of configurations including serial, parallel, i2c, network or USB adapters.

OWFS design

OWFS is a suite of programs that designed to make the 1-wire bus and its devices easily accessible. The underlying principle is to create a virtual filesystem, with the unique ID being the directory, and the individual properties of the device are represented as simple files that can be read and written.

Details of the individual slave or master design are hidden behind a consistent interface. The goal is to provide an easy set of tools for a software designer to create monitoring or control applications. There are some performance enhancements in the implementation, including data caching, parallel access to bus masters, and aggregation of device communication. Still the fundamental goal has been ease of use, flexibility and correctness rather than speed.

DS2409

The DS2409 (3) allows complex 1-wire network topology. Each branch has it's power preserved, even when isolated from the master. A separate PIO pin can be configured to show branch switching, or controlled explicitly.

ADDRESSING

All 1-wire devices are factory assigned a unique 64-bit address. This address is of the form:

Family Code: 8 bits
Address: 48 bits
CRC: 8 bits

Addressing under OWFS is in hexadecimal, of form:

: 01.123456789ABC

where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.

The dot is optional, and the CRC code can included. If included, it must be correct.

DATASHEET

http://pdfserv.maxim-ic.com/en/ds/DS2409.pdf

AVAILABILITY

http://www.owfs.org

AUTHOR

Paul Alfille (paul.alfille@gmail.com)