DS28EA00(3)

💖 DS28EA00 💖

okay bestie, gather round, because we're talking about the DS28EA00 — a 1-Wire Digital Thermometer with Sequence Detect and PIO — and she lives in the One-Wire File System (that's the manual we're in, mwah). she's cute, she's temperature-y, and she has two whole PIO channels which is honestly main character energy. let's get into it 🎀

---

✨ SYNOPSIS ✨

Thermometer, PIO and Chain. that's the vibe, that's the whole vibe.

42 [.]XXXXXXXXXXXX[XX][/[ fasttemp | temperature | temperature9 |
temperature10 | temperature11 | temperature12 | latesttemp | die | power
| temphigh | templow | tempres | PIO.A|B|ALL.BYTE | latch.A|B|ALL.BYTE |
sensed.A|B|ALL.BYTE

address | crc8 | id | locator | r_address | r_id | r_locator | type ]]

---

🌈 FAMILY CODE 🌈

42

that's it. that's the family code. iconic. 💅

---

🦋 SPECIAL PROPERTIES 🦋

power

read-only, yes-no

is the chip powered externally (=1) or parasitically from the data bus (=0)? like, is she plugged in or is she thriving off vibes alone? 🫶

---

🌡️ TEMPERATURE PROPERTIES 🌡️

temperature

read-only, floating point

the measured temperature, at 12 bit resolution. the full-glam measurement.

temperature9 temperature10 temperature11 temperature12

read-only, floating point

measured temperature at 9 to 12 bit resolution. it's a whole tradeoff bestie — time versus accuracy in the temperature measurement. pick your fighter. ✨

latesttemp

read-only, floating point

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 — she's just showing you what she's already got. intended for use in conjunction with /simultaneous/temperature. no cap. 👑

fasttemp

read-only, floating point

equivalent to temperature9. short and sweet, lowkey the speedrun option. 💨

---

🎀 PIO PROPERTIES 🎀

PIO.A|B|ALL|BYTE

read-write, yes-no

two channels of sensors/switches! and yes, we're using the logical rather than electrical interpretation here: 0=off (non-conducting), 1=on (conducting — to ground).

the PIO channels are alternatively used for the sequence-detect (chain) mode. so like, dual-purpose queen.

reading sensed gives the inverse value of the corresponding PIO.

reading PIO gives the actual pin values. use the latch property to see how the pin is set. iykyk. 💜

latch.A|B|ALL|BYTE

read-only, yes-no

the set (intended) value of the PIO pins. the plan, the vision. ✨

sensed.A|B|ALL|BYTE

read-only, yes-no

the actual logical level at the PIO pins. the reality. the vibe check. 🦋

---

🌸 SPECIAL PROPERTIES 🌸

power

read-only, yes-no

is the chip powered externally (=1) or from the parasitically from the data bus (=0)? yes we're saying it again because the page says it again, and honestly, consistency is a slay. 💖

---

🔥 TEMPERATURE ALARM LIMITS 🔥

when the device exceeds either temphigh or templow temperature threshold, the device is in the alarm state, and will appear in the alarm directory. this provides an easy way to poll for temperatures that are unsafe — especially if simultaneous temperature conversion is done. it's giving "hey bestie, something's wrong." 😭

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. she remembers. she always remembers. 👑

temphigh

read-write, integer

shows or sets the lower limit for the high temperature alarm state.

templow

read-write, integer

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

---

⭐ TEMPERATURE RESOLUTION DEFAULT VALUE ⭐

tempres

read-write, integer

the device employs a non-volatile memory to store the default temperature resolution (9, 10, 11 or 12 bits) to be applied after power-up. super useful if you use simultaneous temperature conversions. reading this node gives you the value stored in the non-volatile memory. writing sets a new power-on resolution value.

okay listen, this part matters: as a side effect, reading this node resets the temperature resolution used by simultaneous temperature conversions to its power-on value. it also affects the resolution value used by latesttemp, to scale the latest conversion value — so make sure to re-sample the temperature before accessing latesttemp after writing or reading the tempres value. don't say I didn't warn you bestie 🙈

---

🌈 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. she contains multitudes. 💫

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 she's deprecated. still here, still valid to read, but the era has moved on. 💀

type

read-only, ascii

part name assigned by Dallas Semi. e.g. DS2401. alternative packaging (iButton vs chip) will not be distinguished. she doesn't care about the packaging, only the soul. 🫶

---

🧚 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. one wire doing everything? that's efficiency, that's a slay. ✨

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? obsessed.

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. 💅

DS28EA00

the DS28EA00 (3) is one of several available 1-wire temperature sensors. it is the replacement for the DS18S20 (3). alternatives are DS1822 (3) as well as temperature/voltage measurements in the DS2436 (3) and DS2438 (3). for truly versatile temperature measurements, see the protean DS1921 (3) Thermachron (3).

the DS28EA00 has special switch/sequence detect properties. in sequence mode, the PIO pins are daisy-chained to the next DS28EA00, allowing the system to step through the physical sequence of the DS28EA00s. a little conga line of thermometers, and honestly? iconic. 🎀

---

💜 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 it bestie. 😤

---

📄 DATASHEET 📄

http://pdfserv.maxim-ic.com/en/ds/DS28EA00.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) 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)

---

okay that's the whole page bestie, you made it to the end, I'm so proud of you 🥹💖 this was the OWFS Manpage, dated 2003, and yeah it's the DS28EA00 (3) page, go forth and measure temperatures, slay 💅✨🎀