SYNOPSIS
Real time clock, 4kbit memory. 3-wire interface, too.04.XXXXXXXXXXXX / alarm | auto | cycle | date | delay | interval | memory | pages/page.[0-15|ALL] | readonly/[memory|clock|cycle|interval] | memory | pages/page.[0-15|ALL] | readonly/[memory|clock|cycle|interval] | running | set_alarm | start | trigger/[cycle,date,interval,udate,uinterval] | udate | uinterval | address | crc8 | id | locator | r_address | r_id | r_locator | type
84.XXXXXXXXXXXX / alarm | auto | cycle | date | delay | interval | memory | pages/page.[0-15|ALL] | readonly/[memory|clock|cycle|interval] | running | set_alarm | start | trigger/[cycle,date,interval,udate,uinterval] | udate | uinterval | address | crc8 | id | present | type
FAMILY CODE
- 04
- DS2404 DS1994
- 84
- DS1427 DS2404S
SPECIAL PROPERTIES
alarm
read-write, unsigned integer (0-111)Alarm state of the DS2404 (3) triggered by time or counter events. Reading the alarm state clears the alarm.
The alarm value is of the form CIR, where:
- C
-
cycle
counter alarm
0 no
1 yes - I
-
interval
timer alarm
0 no
1 yes - R
-
real-time clock alarm
0 no
1 yes
auto
read-write, yes-noFlag for mode of interval counter operation. 0=manual 1=auto
See the datasheet for details.
date
read-write, ascii26 character date representation of the udate value. Increments once per second while running
Actual internal representation has higher precision.
Cannot be altered if readonly/clock is set.
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)
delay
read-write, yes-noFlag for adding a delay to cycle counter. 0=short 1-long
See the datasheet under "IDEL" for details.
interval
read-write, dateInterval timer value, represented as a date string. More typically will be used as uinterval to read the actual elapsed seconds.
memory
read-write, binary512 bytes of memory. The readonly/memory flag prevents further change.
pages/page.0 ... pages/page.15 pages/page.ALL
read-write, yes-noMemory is split into 16 pages of 32 bytes each. The readonly/memory flag prevents further change. ALL is an aggregate of the pages. Each page is accessed sequentially.
readonly/[memory|clock|interval|cycle]
read-write, yes-noPermanently protect part of the chip's function from alteration.
- readonly/memory
- page.X and memory
- readonly/clock
- date and udate
- readonly/interval
- interval
- readonly/cycle
- cycle
running
read-write, yes-noState of the clock. 0=off 1=running.
set_alarm
read-write, unsigned integer (0-111)Which of the alarm triggers are enabled in the DS2404 (3)
The set_alarm value is of the form CIR, where:
- C
-
cycle
counter alarm
0 no
1 yes - I
-
interval
timer alarm
0 no
1 yes - R
-
real-time clock alarm
0 no
1 yes
start
read-write, yes-noFlag for starting the interval counter operation if not in auto mode. 0=stop 1=start
See the datasheet for details.
trigger/[cycle,date,interval,udate,uinterval]
read-write,variesTarget value that will trigger the alarm if the corresponding set_alarm field is set.
The format is the same as the similarly named field (i.e. date for trigger/date )
udate
read-write, unsigned integerTime 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.
uinterval
read-write, unsigned intervalSimilar to the udate field, except corresponds to the interval value.
STANDARD PROPERTIES
address
r_address
read-only, asciiThe 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, asciiThe 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, asciiThe 8-bit family code. Unique to each type of device. Given as upper case hexadecimal digits (0-9A-F).
id
r_id
read-only, asciiThe 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, asciiUses 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-noIs the device currently present on the 1-wire bus?
type
read-only, asciiPart 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 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 fundemental goal has been ease of use, flexibility and correctness rather than speed.
DS1427 DS1994 DS2404 DS2404S
The DS1427 (3), DS1994 (3), DS2404 (3), and DS2404S (3) family of 1-wire devices includes clock functions, with timers, memory, counters and alarms. It is possible to write-protect regians of memory. Uses include software or hardware timing and control.
Chips
Both the DS2404 (3) and DS2404S (3) have 1-wire and 3-wire interfaces, which might be useful for transferring data between the 2 buses. They act as a passive slave to both busses. The DS2404 (3) and DS2404S (3) require an external source of power and an external crystal. They also offer a reset and 1HZ clock pin.
iButtons
Both the DS1427 and DS1994 offer the memory, alarms, and clock function in iButton format. Because the iButton is a complete sealed package, battery and crystal are internal. Everything is access via the 1-wire interface.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/DS2404.pdf
http://pdfserv.maxim-ic.com/en/ds/DS2404S-C01.pdf
http://pdfserv.maxim-ic.com/en/ds/DS1994.pdf
http://pdfserv.maxim-ic.com/en/ds/DS1427.pdf