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Table of Contents

Name

DS2415 - 1-Wire Time Chip
DS1904 - RTC iButton
DS2417 - 1-Wire Time Chip with Interrupt

Synopsis

Real time clock.

24 [.]XXXXXXXXXXXX[XX][/[ date | flags | running | udate | address | crc8 | id | locator | present | r_address | r_id | r_locator | type ]]

  1. [.]XXXXXXXXXXXX[XX][/[ date | enable | interval | itime | running | udate | address | crc8 | id | locator | present | r_address | r_id | r_locator | type ]]

Family Code

24 DS2415 DS1904

27 DS2417

Special Properties

date

read-write, ascii
26 character date representation of the counter value. Increments once per second while running
Setting date to a null string will put the current system time.
Accepted date formats are:
Sat[urday] March 12 12:23:59 2001

Apr[il] 4 9:34:56 2002

3/23/04 23:34:57

current locale setting (your system’s format)

enable

read-write, yes-no
State of the timer interrupt. 0=off 1=running.

interval

read-write, unsigned integer
Interval between timer interrupts. Values: 0-7. See table under DESCRIPTION for interpretation. itime will reflect the interval chosen.

itime

read-write, unsigned integer
Interval between timer interrupts. Value in seconds. See table under DESCRIPTION for interpretation and acceptable values. interval will reflect the itime chosen.

flags

read-write, unsigned integer
General use data. 4 bits (0-15 accepted values).

running

read-write, yes-no
State of the clock. 0=off 1=running.

udate

read-write, unsigned integer
Time represented as a number. udate increments once per second, while running is on.
Usually set to unix time standard: number of seconds since Jan 1, 1970. The date field will be the unix representation of udate and setting either will change the other.

Standard Properties

address

r_address

read-only, ascii
The entire 64-bit unique ID. Given as upper case hexidecimal 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 preceeding 56 bits of the unique ID number. Given as upper case hexidecimal digits (0-9A-F).

family

read-only, ascii
The 8-bit family code. Unique to each type of device. Given as upper case hexidecimal 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 hexidecimal 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 hexidecimal) 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

read-only, yes-no
Is the device currently present on the 1-wire bus?
Note, this means that each hex byte (2 characters) is reversed, not the text string.

type

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

Alarms

None implemented.

Description

1-Wire

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

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

The 1-wire bus is accessed via one of a number of serial, parallel or USB adapters.

OWFS design

OWFS is a suite of programs that fundementally make the 1-wire bus and its devices easily accessible. The underlying priciple is to create a virtual filesystem, with the unique ID being the directory, and the individual properties of the device files.

There is optional data caching to improved performance, but possible confusion over stale data.

Ds2415 Ds1904

The DS2415 (3) and DS1904 (3) are simple clocks that can be read on the 1-wire bus. They can also be used the time an event, for remote confirmation.

Ds2417

The DS2417 has the same clock function, but also includes a programmable interval interrupt. Values Allowed are:
0 1sec
1 4sec
2 32s = .5m
3 6 = 1m
4 2048s = .5h
5 4096s = 1h
6 65536s = 18h
7 131072s = 36h

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 hexidecimal, 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/DS2415.pdf
http://pdfserv.maxim-ic.com/en/ds/DS1904.pdf
http://pdfserv.maxim-ic.com/en/ds/DS2417.pdf

See Also

Programs

owfs (1) owhttpd (1) owftpd (1) owserver (1)

Language bindings

owtcl (3) owperl (3)

Clocks

DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)

ID

DS2401 (3) DS1990A (3)

Memory

DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3) DS1996 (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS2804 (3)

Switches

DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3)

Temperature

DS1822 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3)

Humidity

DS1922 (3)

Voltage

DS2450 (3)

Resistance

DS2890 (3)

Multifunction

DS2436 (3) DS2438 (3) DS2760 (3)

Counter

DS2423 (3)

LCD Screen

LCD (3) DS2408 (3)

Crypto

DS1977 (3)

Availability

http://owfs.sourceforge.net

Author

Paul Alfille (palfille@earthlink.net)


Table of Contents

© 2003-4 Paul H. Alfille and The owfs Team
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