DS18S20(3)

okay so bestie, this page is from the One-Wire File System manual, section 3, and it's the whole entire lore on the DS18S20 thermometer 🎀 buckle up, it's giving silicon and it's giving slay.

✨ NAME ✨

DS18S20 — the High-Precision 1-Wire Digital Thermometer 💖

DS1920 — the iButton version of the thermometer 🦋

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🌸 SYNOPSIS 🌸

Thermometer. That's the whole vibe. ✨

10 [.]XXXXXXXXXXXX[XX][/[ fasttemp | temperature | temperature9 |
temperature10 | temperature11 | temperature12 | latesttemp | die | power |
temphigh | templow | trim | trimblanket | trimvalid | address | crc8 |
id | locator | r_address | r_id | r_locator | type ]]

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🎀 FAMILY CODE 🎀

10 — that's the family code, periodt 💅

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👑 SPECIAL PROPERTIES 👑

power

read-only, yes-no.

Is the chip running off external power (=1), or is it mooching parasitically off the data bus (=0)? not me asking the chip about its living situation 😭

temperature

read-only, floating point.

The measured temperature at 12 bit resolution. iconic, honestly.

temperature9 temperature10 temperature11 temperature12

read-only, floating point.

The measured temperature at 9 to 12 bit resolution. heads up bestie: there's a genuine tradeoff of time versus accuracy in the temperature measurement — you can't have both, that's the deal 💀

latesttemp

read-only, floating point.

The measured temperature at 9 to 12 bit resolution, depending on the resolution of the latest conversion on this chip. Reading this node will never trigger a temperature conversion — it's a pure read, no side quests. Intended to be used together with /simultaneous/temperature 🫶

fasttemp

read-only, floating point.

Equivalent to temperature9. lowkey the speedy sibling ⭐

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🌈 TEMPERATURE ALARM LIMITS 🌈

When the device exceeds either the temphigh or templow temperature threshold, the device is in the alarm state, and will show up in the alarm directory. This is genuinely the easy way to poll for temperatures that are unsafe — especially if simultaneous temperature conversion is being done 👑

Units for the temperature alarms are in the same temperature scale that was set for temperature measurements.

Temperature thresholds are stored in non-volatile memory and persist until changed, even if power is lost. no cap, they survive ✨

temphigh

read-write, integer.

Shows or sets the lower limit for the high temperature alarm state. (yes, lower limit for the high alarm, that's what it says bestie, don't come for me 🙈)

templow

read-write, integer.

Shows or sets the upper limit for the low temperature alarm state.

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💀 TEMPERATURE ERRATA 💀

okay so there's a group of obscure internal properties exposed to protect against a hardware defect in certain batches of the B7 die of some DS18x20 chips. See http://www.1wire.org/en-us/pg_18.html or request AN247.pdf from Dallas directly 📄

errata/die

read-only, ascii.

Two character manufacturing die lot. "B6" "B7" or "C2" — that's the whole menu 🎀

errata/trim

read-write, unsigned integer.

The 32 bit trim value in the EEPROM of the chip. When written, it does not seem to read back. Used for a production problem in the B7 die.

Read is allowed for all chips. Only the B7 chips can be written. iykyk 💅

errata/trimblanket

read-write, yes-no.

Writing non-zero (=1) puts a default trim value in the chip. Only applied to the B7 die. Reading will be true (non-zero) if the trim value is the blanket value. Again, only B7 chips will register true, and since the written trim values cannot be read, this value may have little utility. it's giving decorative 🫠

errata/trimvalid

read-only, yes-no.

Is the trim value in the valid range? Non-zero if true — which includes all non-B7 chips. so most of y'all are fine 💖

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⭐ 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 there's no Link Locator 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 this one is DEPRECATED — still documented, still here, but don't build your whole personality on it.

type

read-only, ascii.

Part name assigned by Dallas Semi. E.g. DS2401. Alternative packaging (iButton vs chip) will not be distiguished. 🏷️

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🌸 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. it's literally doing two jobs 💅

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. spicy 🔐

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. pick your fighter 🎀

OWFS design

OWFS is a suite of programs 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 represented as simple files that can be read and written. so cute, so elegant ✨

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. periodt 👑

DS18S20 DS1920

The DS18S20 (3) is one of several available 1-wire temperature sensors. It has been largely replaced by the DS18B20 (3) and DS1822 (3) as well as temperature/vlotage measurements in the DS2436 (3) and DS2438 (3). For truly versatile temperature measurements, see the protean DS1921 (3) Thermachron (3) 🌡️

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🦋 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 be included. If included, it must be correct. no pressure bestie 💀

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📄 DATASHEET 📄

http://pdfserv.maxim-ic.com/en/ds/DS18S20.pdf

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💖 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)

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🌟 AVAILABILITY 🌟

http://www.owfs.org

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🫶 AUTHOR 🫶

Paul Alfille (paul.alfille@gmail.com) — thank you for your service, king 👑

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okay bestie that's the whole page 💖 this came out of the OWFS Manpage, dated 2003, and it's filed under DS18S20(3). now go read a temperature, you icon 🌈✨