Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)512 Byte

19-4990; Rev 12; 11/13

DS1922L/DS1922T

iButton Temperature Loggers

with 8KB Data-Log Memory

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The iButton

temperature loggers (DS1922L/DS1922T)

are rugged, self-sufficient systems that measure tempera-

ture and record the result in a protected memory section.

The recording is done at a user-defined rate. A total of

8192 8-bit readings or 4096 16-bit readings, taken at

equidistant intervals ranging from 1s to 273hr, can be

stored. Additionally, 512 bytes of SRAM store application-

specific information and 64 bytes store calibration data. A

mission to collect data can be programmed to begin imme-

diately, after a user-defined delay, or after a temperature

alarm. Access to the memory and control functions can be

password protected. The DS1922L/DS1922T are config-

ured and communicate with a host-computing device

through the serial 1-Wire

protocol, which requires only a

single data lead and a ground return. Each

DS1922L/DS1922T is factory lasered with a guaranteed

unique 64-bit registration number that allows for absolute

traceability. The durable stainless-steel package is highly

resistant to environmental hazards such as dirt, moisture,

and shock. Accessories permit the DS1922L/DS1922T to

be mounted on almost any object, including containers,

pallets, and bags.

Applications

High-Temperature Logging (Process Monitoring,

Industrial Temperature Monitoring)

Temperature Logging in Cold Chain, Food Safety, Bio

Science, and Pharmaceutical and Medical Products

Features

o Automatically Wakes Up, Measures Temperature,

and Stores Values in 8KB of Data-Log Memory in

8-Bit or 16-Bit Format

o Digital Thermometer Measures Temperature with

8-Bit (0.5°C) or 11-Bit (0.0625°C) Resolution

o Accuracy of ±0.5°C from -10°C to +65°C

(DS1922L), ± 0.5°C from +20°C to +75°C

(DS1922T), with Software Corrections

o Water Resistant or Waterproof if Placed Inside

DS9107 iButton Capsule (Exceeds Water

Resistant 3 ATM Requirements)

o Sampling Rate from 1s Up to 273hr

o Programmable High and Low Trip Points for

Temperature Alarms

o Programmable Recording Start Delay After Elapsed

Time or Upon a Temperature Alarm Trip Point

o Quick Access to Alarmed Devices Through 1-Wire

Conditional Search Function

o 512 Bytes of General-Purpose Memory Plus 64

Bytes of Calibration Memory

o Two-Level Password Protection of All Memory

and Configuration Registers

o Communicates to Host with a Single Digital Signal

Up to 15.4kbps at Standard Speed or Up to

125kbps in Overdrive Mode Using 1-Wire Protocol

o Operating Temperature Range: DS1922L: -40°C to

+85°C; DS1922T: 0°C to +125°C

Common iButton Device Features

o Digital Identification and Information by

Momentary Contact

o Unique Factory-Lasered 64-Bit Registration Number

Ensures Error-Free Device Selection and Absolute

Traceability Because No Two Parts Are Alike

o Built-In Multidrop Controller for 1-Wire Net

o Chip-Based Data Carrier Compactly Stores Information

o Data Can Be Accessed While Affixed to Object

o Button Shape is Self-Aligning with Cup-Shaped

Probes

o Durable Stainless-Steel Case Engraved with

Registration Number Withstands Harsh Environments

o Easily Affixed with Self-Stick Adhesive Backing,

Latched by Its Flange, or Locked with a Ring

Pressed Onto Its Rim

o Presence Detector Acknowledges When Reader

First Applies Voltage

Ordering Information

Denotes a RoHS-compliant device that may include lead(Pb)

that is exempt under the RoHS requirements.

Pin Configuration appears at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

DS1922L-F5# -40°C to +85°C F5 Can

DS1922T-F5# 0°C to +125°C F5 Can

Examples of Accessories

iButton and 1-Wire are registered trademarks of Maxim

Integrated Products, Inc.

PART ACCESSORY

DS9096P Self-Stick Adhesive Pad

DS9101 Multipurpose Clip

DS9093RA Mounting Lock Ring

DS9093A Snap-in FOB

DS9092 iButton Probe

Summary of content (52 pages)

PAGE 1
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory General Description The iButton® temperature loggers (DS1922L/DS1922T) are rugged, self-sufficient systems that measure temperature and record the result in a protected memory section. The recording is done at a user-defined rate. A total of 8192 8-bit readings or 4096 16-bit readings, taken at equidistant intervals ranging from 1s to 273hr, can be stored.
PAGE 2
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ABSOLUTE MAXIMUM RATINGS IO Voltage Range to GND ........................................-0.3V to +6V IO Sink Current....................................................................20mA Operating Temperature Range DS1922L ...........................................................-40°C to +85°C DS1922T ............................................................0°C to +125°C Junction Temperature .......................................
PAGE 3
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ELECTRICAL CHARACTERISTICS (continued) (VPUP = +3.0V to +5.25V.) PARAMETER Presence-Detect Low Time Presence-Detect Sample Time (Note 2) SYMBOL tPDL tMSP CONDITIONS MIN TYP MAX Standard speed, VPUP > 4.5V 60 240 Standard speed (Note 12) 60 287 Overdrive speed, VPUP > 4.5V (Note 12) Overdrive speed (Note 12) 7 24 7 28 Standard speed, VPUP > 4.5V 65 75 Standard speed 71.
PAGE 4
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ELECTRICAL CHARACTERISTICS (continued) (VPUP = +3.0V to +5.25V.) Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: Note 14: Note 15: Note 16: Note 17: Note 18: Note 19: Note 20: The voltage on IO must be less than or equal to VILMAX whenever the master drives the line low. Voltage above which, during a rising edge on IO, a logic 1 is detected.
PAGE 5
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs.
PAGE 6
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs.
PAGE 7
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs.
PAGE 8
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs.
PAGE 9
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs. Sample Rate 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) 10 0°C +40°C -40°C +60°C +75°C 1 +85°C 0.1 0.01 0.01 0.1 1 10 100 MINUTES BETWEEN SAMPLES 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) 10 0°C +40°C -40°C +60°C +75°C 1 +85°C 0.1 0.01 0.001 0.01 0.
PAGE 10
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs. Sample Rate 10 0°C +40°C 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) +60°C +75°C 1 +85°C +95°C +110°C 0.1 +125°C 0.01 0.01 0.1 1 10 100 MINUTES BETWEEN SAMPLES 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) 10 0°C +40°C +60°C +75°C 1 +85°C +95°C +110°C 0.1 +125°C 0.01 0.001 0.01 0.
PAGE 11
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922L Temperature Accuracy 2.0 1.5 ERROR (°C) 1.0 UNCORRECTED MAXIMUM ERROR 0.5 SW CORRECTED MAXIMUM ERROR 0.0 SW CORRECTED MINIMUM ERROR -0.5 UNCORRECTED MINIMUM ERROR -1.0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) NOTE: THE GRAPHS ARE BASED ON 11-BIT DATA. DS1922T Temperature Accuracy 2.5 2.0 1.5 ERROR (°C) 1.0 UNCORRECTED MAXIMUM ERROR 0.5 SW CORRECTED MAXIMUM ERROR 0.
PAGE 12
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory DS1922L RTC Accuracy (Typical) 2.0 1.0 DRIFT (MINUTES/MONTH) 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) DS1922T RTC Accuracy (Typical) 2.0 0.0 DRIFT (MINUTES/MONTH) -2.0 -4.0 -6.0 -8.0 -10.0 -12.
PAGE 13
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Detailed Description The DS1922L is an ideal device to monitor for extended periods of time the temperature of any object it is attached to or shipped with, such as fresh produce, medical drugs and supplies, and for use in refrigerators and freezers. With its shifted temperature range, the DS1922T is suited to monitor processes that require temperatures close to the boiling point of water, such as pasteurization of food items.
PAGE 14
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 1-Wire PORT ROM FUNCTION CONTROL IO 64-BIT LASERED ROM MEMORY FUNCTION CONTROL 3V LITHIUM PARASITE-POWERED CIRCUITRY 256-BIT SCRATCHPAD DS1922L DS1922T GENERAL-PURPOSE SRAM (512 BYTES) INTERNAL TIMEKEEPING, CONTROL REGISTERS, AND COUNTERS 32.768kHz OSCILLATOR THERMAL SENSE REGISTER PAGES (64 BYTES) CALIBRATION MEMORY (64 BYTES) ADC CONTROL LOGIC DATA-LOG MEMORY 8KB Figure 1.
PAGE 15
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 1-Wire NET BUS MASTER OTHER DEVICES DS1922L/DS1922T COMMAND LEVEL: AVAILABLE COMMANDS: DATA FIELD AFFECTED: 1-Wire ROM FUNCTION COMMANDS READ ROM MATCH ROM SEARCH ROM CONDITIONAL SEARCH ROM SKIP ROM RESUME OVERDRIVE-SKIP ROM OVERDRIVE-MATCH ROM 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG 64-BIT ROM, RC-FLAG, ALARM FLAGS, SEARCH CONDITIONS RC-FLAG RC-FLAG RC-FLAG, OD-FLAG 64-BIT ROM, RC-FLAG, OD-FLAG WRITE SCRATCHPA
PAGE 16
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Memory Figure 5 shows the DS1922L/DS1922T memory map. Pages 0 to 15 contain 512 bytes of general-purpose SRAM. The various registers to set up and control the device fill pages 16 and 17, called register pages 1 and 2 (see Figure 6 for details). Pages 18 and 19 provide storage space for calibration data. They can alternatively be used as an extension of the generalpurpose memory.
PAGE 17
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ADDRESS BIT 7 0200h 0 BIT 6 10 Seconds Single Seconds 0201h 0 10 Minutes Single Minutes 0202h 0 12/24 20 Hour AM/PM 0203h 0 0 0204h CENT 0 0205h BIT 5 BIT 3 10 Hour 0 BIT 2 BIT 1 BIT 0 Single Date 10 Months R/W R Sample Rate R/W R Temperature Alarms R/W R — R/W R Latest Temperature R R — R R Single Years Low Byte 0 High Byte 0208h Low Threshold 0209h High Threshold 020Ah (No Function
PAGE 18
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ADDRESS BIT 7 0219h 0 10 Seconds Single Seconds 021Ah 0 10 Minutes Single Minutes 021Bh 0 12/24 20 Hour AM/PM 021Ch 0 0 021Dh CENT 0 021Eh BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 10 Hour Single Hours 10 Date 0 BIT 1 Single Date 10 Months BIT 0 FUNCTION ACCESS* Mission Timestamp R R Single Months 10 Years Single Years 021Fh (No Function; Reads 00h) — R R 0220h Low Byte 0221h Center Byte R R 0222h H
PAGE 19
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Detailed Register Descriptions Timekeeping and Calendar The RTC and calendar information is accessed by reading/writing the appropriate bytes in the register page, address 0200h to 0205h. For readings to be valid, all RTC registers must be read sequentially starting at address 0200h. Some of the RTC bits are set to 0. These bits always read 0 regardless of how they are written.
PAGE 20
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Temperature Conversion This equation is valid for converting temperature readings stored in the data-log memory as well as for data read from the Latest Temperature Conversion Result register. The “-41” applies to the DS1922L. For the DS1922T, use “-1” instead of “-41.” To specify the temperature alarm thresholds, the previous equations are resolved to: The DS1922L’s temperature range begins at -40°C and ends at +85°C.
PAGE 21
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Temperature Sensor Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0210h 0 0 0 0 0 0 ETHA ETLA Note: During a mission, there is only read access to this register. Bits 2 to 7 have no function. They always read 0 and cannot be written to 1.
PAGE 22
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Mission Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0213h 1 1 SUTA RO (X) TLFS 0 ETL Note: During a mission, there is only read access to this register. Bits 6 and 7 have no function. They always read 1 and cannot be written to 0. Bits 1 and 3 control functions that are not available with the DS1922L/DS1922T. Bit 1 must be set to 0.
PAGE 23
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Alarm Status Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0214h BOR 1 1 1 0 0 THF TLF Note: There is only read access to this register. Bits 4 to 6 have no function. They always read 1. Bits 2 and 3 have no function with the DS1922L/DS1922T. They always read 0. The alarm status bits are cleared simultaneously when the Clear Memory Function is invoked.
PAGE 24
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Mission Start Delay Counter Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 0216h Delay Low Byte 0217h Delay Center Byte 0218h Delay High Byte BIT 2 BIT 1 BIT 0 Note: During a mission, there is only read access to this register.
PAGE 25
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Device Samples Counter Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 0223h Low Byte 0224h Center Byte 0225h High Byte BIT 2 BIT 1 BIT 0 Note: There is only read access to this register.
PAGE 26
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Read Access Password Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0228h RP7 RP6 RP5 RP4 RP3 RP2 RP1 RP0 0229h RP15 RP14 RP13 RP12 RP11 RP10 RP9 RP8 … … 022Eh RP55 RP54 RP53 RP52 RP51 RP50 RP49 RP48 022Fh RP63 RP62 RP61 RP60 RP59 RP58 RP57 RP56 Note: There is only write access to this register. Attempting to read the password reports all zeros.
PAGE 27
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ETL = 1 TLFS = 0 ETL = 1 TLFS = 1 1000h 8192 8-BIT ENTRIES TEMPERATURE 1000h 4096 16-BIT ENTRIES TEMPERATURE 2FFFh WITH 16-BIT FORMAT, THE MOST SIGNIFICANT BYTE IS STORED AT THE LOWER ADDRESS. 2FFFh Figure 7. Temperature Logging Data-Log Memory Usage Once set up for a mission, the DS1922L/DS1922T log the temperature measurements at equidistant time points entry after entry in their data-log memory.
PAGE 28
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory The last step to begin a mission is to issue the Start Mission command. As soon as they have received this command, the DS1922L/DS1922T set the MIP flag and clear the MEMCLR flag. With the immediate/delayed start mode (SUTA = 0), and after as many minutes as specified by the Mission Start Delay are over, the device wakes up, copies the current date and time to the Mission Timestamp register, and logs the first entry of the mission.
PAGE 29
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory corresponding ending offset in this example is 1Fh. For best economy of speed and efficiency, the target address for writing should point to the beginning of a page, i.e., the byte offset is 0. Thus, the full 32-byte capacity of the scratchpad is available, resulting also in the ending offset of 1Fh. The ending offset together with the PF flag are a means to support the master checking the data integrity after a Write command.
PAGE 30
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Read Scratchpad [AAh] This command is used to verify scratchpad data and target address. After issuing the Read Scratchpad command, the master begins reading. The first 2 bytes are the target address. The next byte is the ending offset/data status byte (E/S) followed by the scratchpad data beginning at the byte offset T[4:0], as shown in Figure 8.
PAGE 31
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory MASTER Tx MEMORY OR CONTROL FUNCTION COMMAND 0Fh WRITE SCRATCHPAD? FROM ROM FUNCTIONS FLOWCHART (FIGURE 11) AAh READ SCRATCHPAD? N Y 99h COPY SCRATCHPAD [WITH PW] N Y Y MASTER Rx TA1 [T7:T0] MASTER Tx TA1 [T7:T0] TO FIGURE 9b N MASTER Tx TA1 [T7:T0], TA2 [T15:T8] AUTHORIZATION CODE MASTER Tx TA2 [T15:T8] MASTER Rx TA2 [T15:T8] MASTER Tx E/S BYTE DS1922 SETS SCRATCHPAD OFFSET = [T4:T0] AND CLEARS (PF, AA) MASTER Rx ENDING
PAGE 32
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 69h READ MEMORY [WITH PW] AND CRC FROM FIGURE 9a 96h CLEAR MEMORY [WITH PW] N Y Y DECISION MADE BY DS1922 55h FORCED CONVERSION? N MASTER Tx TA1 [T7:T0], TA2 [T15:T8] MASTER Tx 64 BITS [PASSWORD] MASTER Tx 64 BITS [PASSWORD] MASTER Tx FFh DUMMY BYTE N TO FIGURE 9c Y MASTER Tx FFh DUMMY BYTE MISSION IN PROGRESS? Y N PASSWORD ACCEPTED? N PASSWORD ACCEPTED? Y DECISION MADE BY MASTER MISSION IN PROGRESS? DS1922 COPIES
PAGE 33
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory CCh START MISSION [WITH PW] FROM FIGURE 9b 33h STOP MISSION [WITH PW] N MISSION START DELAY PROCESS Y N Y MASTER Tx 64 BITS [PASSWORD] MASTER Tx 64 BITS [PASSWORD] START DELAY COUNTER = 0? MASTER Tx FFh DUMMY BYTE Y MASTER Tx FFh DUMMY BYTE N DS1922 WAITS FOR 1 MINUTE N PASSWORD ACCEPTED? PASSWORD ACCEPTED? DS1922 DECREMENTS START DELAY COUNTER Y Y Y MISSION IN PROGRESS? SUTA = 1? N N DS1922 WAITS ONE SAMPLE PERIOD
PAGE 34
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Clear Memory with Password [96h] Start Mission with Password [CCh] The Clear Memory with Password command is used to prepare the device for another mission. This command is only executed if no mission is in progress. After the command code the master must transmit the 64-bit fullaccess password followed by an FFh dummy byte.
PAGE 35
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Memory Access Conflicts While a mission is in progress or while the device is waiting for a temperature alarm to start a mission, periodically a temperature sample is taken and logged. This “internal activity” has priority over 1-Wire communication. As a consequence, device-specific commands (excluding ROM function commands and 1-Wire reset) do not perform properly when internal and “external” activities interfere with each other.
PAGE 36
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 1-Wire Bus System of the pullup resistor primarily depends on the network size and load conditions. The DS1922L/DS1922T require a pullup resistor of maximum 2.2kΩ at any speed. The 1-Wire bus is a system that has a single bus master and one or more slaves. In all instances the DS1922L/DS1922T are slave devices. The bus master is typically a microcontroller.
PAGE 37
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Initialization All transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequence consists of a reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the slave(s). The presence pulse lets the bus master know that the DS1922L/DS1922T are on the bus and are ready to operate. For more details, see the 1-Wire Signaling section.
PAGE 38
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Skip ROM [CCh] This command can save time in a single-drop bus system by allowing the bus master to access the memory functions without providing the 64-bit ROM code. For example, if more than one slave is present on the bus and a read command is issued following the Skip ROM command, data collision occurs on the bus as multiple slaves transmit simultaneously (open-drain pulldowns produce a wired-AND result).
PAGE 39
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory BUS MASTER Tx RESET PULSE FROM FIGURE 11b FROM MEMORY/CONTROL FUNCTION FLOWCHART (FIGURE 9) OD RESET PULSE? N OD = 0 Y BUS MASTER Tx ROM FUNCTION COMMAND 33h READ ROM COMMAND? DS1922 Tx PRESENCE PULSE N 55h MATCH ROM COMMAND? F0h SEARCH ROM COMMAND? N ECh CONDITIONAL SEARCH COMMAND? N Y Y Y Y RC = 0 RC = 0 RC = 0 RC = 0 N N TO FIGURE 11b CONDITION MET? Y DS1922 Tx FAMILY CODE (1 BYTE) DS1922 Tx BIT 0 MASTER Tx BI
PAGE 40
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory TO FIGURE 11a FROM FIGURE 11a CCh SKIP ROM COMMAND? N Y A5h RESUME COMMAND? 3Ch OVERDRIVESKIP ROM? N Y N Y RC = 1? N Y RC = 0; OD = 1 RC = 0 69h OVERDRIVEMATCH ROM? RC = 0; OD = 1 N Y MASTER Tx RESET? Y MASTER Tx BIT 0 N (SEE NOTE) MASTER Tx RESET? N Y BIT 0 MATCH? N OD = 0 Y MASTER Tx BIT 1 (SEE NOTE) BIT 1 MATCH? N OD = 0 Y MASTER Tx BIT 63 (SEE NOTE) BIT 63 MATCH? N OD = 0 Y FROM FIGURE 11a RC = 1
PAGE 41
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 1-Wire Signaling drive mode and tRSTL is no longer than 80µs, the device remains in overdrive mode. The DS1922L/DS1922T require strict protocols to ensure data integrity. The protocol consists of four types of signaling on one line: reset sequence with reset pulse and presence pulse, write-zero, write-one, and read-data. Except for the presence pulse, the bus master initiates all these signals.
PAGE 42
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Master-to-Slave For a write-one time slot, the voltage on the data line must have crossed the VTH threshold before the write-one low time tW1LMAX is expired. For a write-zero time slot, the voltage on the data line must stay below the VTH threshold until the write-zero low time tW0LMIN is expired. The voltage on the data line should not exceed VILMAX during the entire tW0L or tW1L window.
PAGE 43
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory WRITE-ONE TIME SLOT tW1L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tSLOT RESISTOR MASTER WRITE-ZERO TIME SLOT tW0L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tREC tSLOT RESISTOR MASTER READ-DATA TIME SLOT tMSR tRL VPUP VIHMASTER VTH MASTER SAMPLING WINDOW VTL VILMAX 0V δ tF tREC tSLOT RESISTOR MASTER DS1922L/DS1922T Figure 13.
PAGE 44
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory tREH tREH VPUP VTH VHY CASE A CASE B CASE C 0V tGL tGL Figure 14. Noise Suppression Scheme POLYNOMIAL = X16 + X15 + X2 + 1 1ST STAGE X0 X2 X1 9TH STAGE X8 3RD STAGE 2ND STAGE 10TH STAGE X9 11TH STAGE X10 4TH STAGE X3 12TH STAGE X11 5TH STAGE X4 13TH STAGE X12 6TH STAGE X5 14TH STAGE X13 7TH STAGE X6 8TH STAGE X7 15TH STAGE X14 16TH STAGE X15 X16 CRC OUTPUT INPUT DATA Figure 15.
PAGE 45
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory ing in the command code, the target addresses TA1 and TA2, and all the data bytes. The DS1922L/DS1922T transmit this CRC only if the data bytes written to the scratchpad include scratchpad ending offset 11111b. The data can start at any location within the scratchpad.
PAGE 46
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Command-Specific 1-Wire Communication Protocol—Color Codes Master-to-Slave Slave-to-Master 1-Wire Communication Examples Write Scratchpad, Reaching the End of the Scratchpad (Cannot Fail) RST PD Select WS TA CRC-16 FF Loop Read Scratchpad (Cannot Fail) RST PD Select RS TA-E/S CRC-16 FF Loop Copy Scratchpad with Password (Success) RST PD Select CPS TA-E/S Busy AA Loop Copy Scratchpad wit
PAGE 47
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory 1-Wire Communication Examples (continued) Forced Conversion RST PD Select FC FFh FF Loop To read the result and to verify success, read the addresses 020Ch to 020Fh (results) and the Device Samples Counter at address 0223h to 0225h. If the count has incremented, the command was executed successfully.
PAGE 48
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Step 2: Write the setup data to register page 1.
PAGE 49
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory With only a single device connected to the bus master, the communication of step 2 looks like this: MASTER MODE DATA (LSB FIRST) Tx (Reset) Rx (Presence) Tx CCh Issue “Skip ROM” command Tx 0Fh Issue “Write Scratchpad” command Tx 00h TA1, beginning offset = 00h Tx 02h Tx <25 Data Bytes> Tx <7 FFh Bytes> Tx (Reset) Rx (Presence) Tx CCh Issue “Skip ROM” command Tx AAh Issue “Read Scratchpad” command Rx 00h Rea
PAGE 50
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Software Correction Algorithm for Temperature The correction algorithm consists of two steps: preparation and execution. By means of the family code the preparation step verifies whether the device actually is a DS1922. Then the configuration byte is checked to identify the type of DS1922 (L or T). If it is the correct device, the data for software correction is read and converted from binary to decimal °C format.
PAGE 51
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Numerical Correction Example 5.89mm 0.51mm — Err3 = -0.1483°C Tc2 = -10.0625°C Err1 = 0.0672°C Tc3 = 24.5°C — A1 — A = 0.000175/°C TC = 22.500°C C = -0.039332°C TCORR = 22.647°C Note: The software correction requires floating-point arithmetic (24 bit or better). Suitable math libraries for microcontrollers are found on various websites and are included in cross compilers. ® 41 1-Wire® W W B = -0.008741 16.
PAGE 52
DS1922L/DS1922T iButton Temperature Loggers with 8KB Data-Log Memory Revision History REVISION NUMBER 7 REVISION DATE DESCRIPTION PAGES CHANGED 12/07 Added bullet “Water resistant or waterproof if placed inside DS9107 iButton capsule (Exceeds Water Resistant 3 ATM requirements)”; deleted “application pending” from UL bullet and safety statement; added text to Application section: Note that the initial sealing level of DS1922L/DS1922T achieves IP56.