DS2502(3)

📦 version 3.2_p4, in alpine 3.24, debian bookworm, debian trixie, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 DS2502 — Add-Only Memory (1 kBit) 💖

okay so welcome to the One-Wire File System manual, section 3, bestie. This is the page for DS2502 and its whole little friend group 🫶

✨ NAME ✨

DS2502 — Add-Only Memory (1 kBit)

and also, same page, same energy:

  • DS2502-E48, DS2502-UNW — 48-bit Node Address Chip, UniqueWare Add-Only Memory (1 kBit)
  • DS1982, DS1982U — Add-Only iButton (1 kBit), UniqueWare iButton (1 kBit)

✨ SYNOPSIS ✨

EPROM add-only memory. that's the whole vibe, it just sits there being add-only 🎀

09 [.]XXXXXXXXXXXX[XX][/[ memory | pages/page.[0-3|ALL] | address | crc8 | id | locator | r_address | r_id | r_locator | type ]]
89 [.]XXXXXXXXXXXX[XX][/[ mac_e | mac_fw | memory | pages/page.[0-3|ALL] | project | address | crc8 | id | locator | r_address | r_id | r_locator | type ]]

✨ FAMILY CODE ✨

  • 09 — DS2502 DS1982
  • 89 — DS2502-UNW DS2502-E48 DS1982U

✨ SPECIAL PROPERTIES ✨

🦋 mac_e, mac_fw

read-only, binary. it's a 64 bit or 80 bit media access control number. Unique, and literally unrelated to the 1-wire address — like, they're not even mutuals. Apparently it's used for ethernet or FireWire addressing, respectively.

🦋 memory

read-write, binary. 128 bytes of memory. Initially all bits are set to 1. Writing a zero permanently alters the memory. permanent permanent, no take-backs 💀

🦋 pages/page.0 ... pages/page.3, pages/page.ALL

read-write, yes-no. Memory is split into 4 pages of 32 bytes each. ALL is an aggregate of the pages. Each page is accessed sequentially, one at a time, no cutting the line.

🦋 project

read-only, binary. a 32 bit project id. Constant 0x0000 for ethernet and 0x00001128 for firewire. See Datasheets.

✨ 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?

bestie it says DEPRECATED right there in the name, so, like, noted 👀

💜 type

read-only, ascii. Part name assigned by Dallas Semi. E.g. DS2401. Alternative packaging (iButton vs chip) will not be distinguished — it does not clock the difference, fr fr.

✨ ALARMS ✨

None. not a single one. peaceful. serene. 🧚

✨ 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 — yes, the data line is doing double duty, main character energy.

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. it's giving "everything is a file" and honestly? iconic.

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.

🌸 DS2502, DS1982

The DS2502 (3) is used for write-once incremental storage. It's main advantage is for audit trails (i.e. a digital purse) 💰

The DS2502-E48 and DS2502-UNW are some of the UniqueWare class of devices. Some of the memory was preprogramed at the factory. See the datasheet for specifics. The DS2502, DS2505, and DS2506 differ in their function by the amount of on-board memory they possess. (The internal protocols are slightly different, but the OWFS system handles this automatically. so you don't have to, bestie, you're welcome 🫶)

✨ 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. no faking the CRC, the vibe check will catch you 😭

✨ DATASHEET ✨

✨ 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) InfernoEmbedded (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 (3) EDS0066 (3) EDS0068 (3)

🌈 Moisture

EEEF (3) DS2438 (3)

✨ AVAILABILITY ✨

http://www.owfs.org

✨ AUTHOR ✨

Paul Alfille (paul.alfille@gmail.com) — actual legend, no cap 👑

and that's the whole page, bestie!! this was the OWFS Manpage, dated 2003, section DS2502(3) — go forth and read your add-only memory, ily 💖✨🎀

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