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NAME
DS28EC20 - EEPROM (20 kBit)
SYNOPSIS
Erasable programmable read-only memory (EEPROM)
43 [.]XXXXXXXXXXXX[XX][/[ memory | pages/page.[0-79|ALL] | address | crc8 | id | locator |
r_address | r_id | r_locator | type ]]
FAMILY CODE
23 DS28EC20
SPECIAL PROPERTIES
memory
read-write, binary
512 bytes of memory. Initially all bits are set to 1. Writing zero permanently alters the
memory.
pages/page.0 ... pages/page.79 pages/page.ALL
read-write, yes-no
Memory is split into 80 pages of 32 bytes each. ALL is an aggregate of the pages. Each
page is accessed sequentially.
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
preceding 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 (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
None.
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.
DS28EC20
The DS28EC20 (3) is used for storing memory which should be available even after a reset
or power off. It's main advantage is for audit trails (i.e. a digital purse). OWFS system
handles this automatically.
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://datasheets.maxim-ic.com/en/ds/DS28EC20.pdf
SEE ALSO
Programs
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1) owwrite (1) owpresent
(1) owtap (1)
Configuration and testing
owfs (5) owtap (1) owmon (1)
Language bindings
owtcl (3) owperl (3) owcapi (3)
Clocks
DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)
ID
DS2401 (3) DS2411 (3) DS1990A (3)
Memory
DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3) DS1996 (3)
DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3) DS28EC20 (3)
Switches
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3)
Temperature
DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3)
DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3) EDS0066 (3) EDS0067 (3) EDS0068 (3)
EDS0071 (3) EDS0072 (3) MAX31826 (3)
Humidity
DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)
Voltage
DS2450 (3)
Resistance
DS2890 (3)
Multifunction (current, voltage, temperature)
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3) DS2770 (3)
DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
Counter
DS2423 (3)
LCD Screen
LCD (3) DS2408 (3)
Crypto
DS1977 (3)
Pressure
DS2406 (3) TAI8570 EDS0066 (3) EDS0068 (3)
Moisture
EEEF (3) DS2438 (3)
AVAILABILITY
http://www.owfs.org
AUTHOR
Christian Magnusson (mag@mag.cx)