iButton
iButton is a brand name of Dallas Semiconductor or, since 2001, Maxim Integrated . An iButton is an integrated circuit with a single-wire technology interface. The housings (Microcan F5 (17.35 x 5.89 mm) and the somewhat rarer flat Microcan F3 (17.35 x 3.1 mm)) are made of 0.254 mm thick stainless steel and are similar to a button cell with a 16 mm diameter.
There are different types, which are ROM , NVRAM , EPROM , EEPROM , RTC , microcontrollers , different sensors or protocol memories e.g. B. for temperature or humidity . The housings can be installed in various brackets, e.g. B. in key rings, bracelets or transport containers.
What they all have in common is the globally unique 64-bit serial number (consisting of 8-bit family code, 48-bit number (unique device ID) and 8-bit cyclic redundancy check checksum) and the OneWire interface.
Some iButtons (DS1904 RTC, DS1921… 923 Logger, DS1954-57 Java, DS1991… 1996 RAMs) contain a BR1220 or BR1225 lithium button cell .
The manufacturer, designation, date of manufacture and the serial number are also laser-engraved on the stainless steel housing, unless the customer requests his own, chargeable inscription.
Maxim and other manufacturers offer a variety of adapters, such as: B. for the serial interface (DS9097) or the USB connection (DS9490), in order to be able to connect 1-wire components with computers. There is a series of iButton probes (DS140x and DS909x) to establish physical contact.
Although Dallas / Maxim pretends security with the "worldwide unique serial number" and encryption method, most iButtons are not secure, as their function can be emulated with fast microcontrollers or FPGAs. At the 27C3 in 2010 it was published how a SHA-iButton that was previously considered safe could be copied.
Some iButton types e.g. B. DS1922L can be set and read out via Android apps .
| Type | function | description |
|---|---|---|
| DS1990A, DS1990R | iButton | a globally unique serial number in a 64- bit - ROM |
| DS1991L | Multikey iButton | password-protected, non-volatile memory; is no longer produced |
| DS1992L | NVRAM | 1 kBit |
| DS1993L | NVRAM | 4 kBit |
| DS1994L | NVRAM | 4 kBit, with real-time clock (RTC) |
| DS1995L | NVRAM | 16 kBit |
| DS1996L | NVRAM | 64 kBit |
| DS1982 | add-only EPROM | 1 kBit |
| DS1985 | add-only EPROM | 16 kBit |
| DS1986 | add-only EPROM | 64 kBit |
| DS1971 | EEPROM | 256 bit |
| DS1972 | EEPROM | 1 kBit |
| DS1973 | EEPROM | 4 kBit |
| DS1977 | EEPROM | 32 kByte |
| DS1904 | Real time clock (RTC) | |
| DS1961S | EEPROM | 1 kBit, with SHA hash |
| DS1963S | NV RAM | 4 kBit, with SHA hash |
| DS1954 | cryptographic iButton | Java powered |
| DS1955 | cryptographic iButton | Java-powered, (64 kB ROM, 6 kB… 134 kB NVRAM) |
| DS1957 | cryptographic iButton | Java powered |
| DS195x-yyy / RINGzzz | iButton | in the finger ring (zzz = size specification of the ring diameter) |
| DS1920 | Temperature sensor | 0.5000 ° C resolution, −55… +100 ° C, (resolution can be increased) |
| DS1921G | 2 kbyte temperature logger | 0.5000 ° C resolution, −40 ... + 85 ° C |
| DS1921H | 2 kbyte temperature logger | 0.1250 ° C resolution, +15… + 46 ° C |
| DS1921Z | 2 kbyte temperature logger | 0.1250 ° C resolution, - 5… + 26 ° C |
| DS1922E | 8 kbyte temperature logger | 0.0625 ° C resolution, +15… +140 ° C |
| DS1922L | 8 kbyte temperature logger | 0.0625 ° C resolution, −40 ... + 85 ° C |
| DS2422L | 8 kbyte temperature logger | 0.0625 ° C resolution, −40… + 85 ° C; is no longer produced |
| DS1922T | 8 kbyte temperature logger | 0.0625 ° C resolution, 0… +125 ° C |
| DS1923 | 8 kbyte data logger | for humidity and temperature (0… 100% RH and −20 ° C… +85 ° C, 0.0625 ° C resolution) |
| DS9107 | iButton capsule | (25.4 x 16.6 mm²). This screw jar has protection class IP68. |
| DS9108 | Dipstick | for temperature measurement with 3 × DS1921G |
Special application examples
- Key replacement
- Time recording for employees
- To identify employees in the catering industry at the cash register, at dispensing systems.
- Ticket / credit card replacement
- Cryptography
- Tracking the core body temperature in the vaginal canal in cows, horses and camels.
- Registration of the human body core temperature (e.g. in hospitals)
- Sign of body temperature to the basal body temperature and the Symptothermal method the fertility to determine the woman
- long-term monitoring of refrigerated goods (e.g. food and pharmaceutical products)
Web links
Individual evidence
- ↑ CCC: Hacking iButton. Retrieved June 15, 2018 .
- ^ Photo of a Java ring ( Memento from August 1, 2016 in the Internet Archive ) from Sun Microsystems
- ↑ Photo of a Java ring on the left hand ( Memento from March 4, 2016 in the Internet Archive )
- ↑ Basal thermometer for NFP & cycle app with symptothermal method - youtube.com
