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iButton DESCRIPTION

The DS1977 is a 32KB EEPROM in a rugged,

Button

enclosure. Access to the memory can be

password-protected with different passwords for

read-only and full access. Data is transferred serially

through the 1-Wire

protocol, which requires only a

single data lead and a ground return. Every DS1977

is factory lasered with a guaranteed unique 64-bit

registration number that allows for absolute

traceability. The durable stainless-steel i

Button

package is highly resistant to environmental hazards

such as dirt, moisture, and shock. Accessories permit

the DS1977 i

Button to be mounted on almost any

object, including containers, pallets, and bags.

APPLICATIONS

Maintenance/Inspection Data Storage

Medical Data Carrier

Health Data Carrier

Audit Data Storage and Carrier

F5 MicroCAN

GND

0.51

5.89

16.25

17.35

FC 37

000000FBC52B

1-Wire



All dimensions are shown in millimeters.

SPECIAL FEATURES

 32KB EEPROM Organized as Pages of 64 Bytes

Each

 Optional Password Protection with Different 64-

Bit Passwords for Read and Full Access

 Communicates to Host with a Single Digital

Signal at Up to 15.3kbps at Standard Speed or

Up to 125kbps in Overdrive Mode Using 1-Wire

Protocol

 Operating Range: 2.8V to 5.25V, -40°C to +85°C

 Minimum 100k Write Cycles Endurance

 15kV Built-in ESD Protection

COMMON iButton FEATURES

 Unique Factory-Lasered 64-Bit Registration

Number Assures Error-Free Device Selection

and Absolute Traceability Because No Two Parts

are Alike

 Built-In Multidrop Controller for 1-Wire Net

 Chip-Based Data Carrier Stores Digital

Identification and Information, Armored in a

Durable Stainless-Steel Case

 Data can be Accessed While Affixed to Object

 Button Shape is Self-Aligning with Cup-Shaped

Probes

 Easily Affixed with Self-Stick Adhesive Backing,

Latched by its Flange, or Locked with a Ring

Pressed onto its Rim

 Presence Detector Acknowledges when Reader

First Applies Voltage

ORDERING INFORMATION

PART TEMP RANGE PACKAGE

DS1977-F5#

-40°C to +85°C

F5 iButton

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

is exempt under the RoHS requirements.

EXAMPLES OF ACCESSORIES

PART DESCRIPTION

DS9096P

Self-Stick Adhesive Pad

DS9101

Multipurpose Clip

DS9093RA

Mounting Lock Ring

DS9093A

Snap-In Fob

DS9092

iButton Probe

iButton and 1-Wire are registered trademarks of Maxim

Integrated Products, Inc.

19-4890; Rev 11/09

DS1977

Password-Protected 32KB EEPROM iButton

Summary of content (29 pages)

PAGE 1
9-4890; Rev 11/09 DS1977 Password-Protected 32KB EEPROM iButton iButton DESCRIPTION SPECIAL FEATURES The DS1977 is a 32KB EEPROM in a rugged, iButton® enclosure. Access to the memory can be password-protected with different passwords for read-only and full access. Data is transferred serially through the 1-Wire® protocol, which requires only a single data lead and a ground return. Every DS1977 is factory lasered with a guaranteed unique 64-bit registration number that allows for absolute traceability.
PAGE 2
DS1977 PHYSICAL SPECIFICATION Size Weight DS1977 See mechanical drawing Ca. 3.3g ABSOLUTE MAXIMUM RATINGS I/O Voltage to GND I/O Sink Current Junction Temperature Storage Temperature Range -0.3V, +5.5V 20mA +150°C -40°C to +85°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
PAGE 3
DS1977 PARAMETER SYMBOL Presence Detect Sample Time CONDITIONS Standard speed, VPUP > 4.5V (Note 1) Standard speed (Note 1) Overdrive speed (Note 1) MIN TYP MAX UNITS 65 75 68 7.5 75 10.5 Standard speed (Notes 1, 13) Overdrive speed (Notes 1, 13) Standard speed (Notes 1, 13) Overdrive speed (Notes 1, 13) 60 6 5 1 120 16 15 2 Standard speed (Notes 1, 14) Overdrive speed (Notes 1, 14) Standard speed, VPUP > 4.
PAGE 4
DS1977 APPLICATION The DS1977 is an ideal device to store maintenance and inspection data of equipment or medical- and healthrelated data in digitally readable format. Due to its small size and rugged enclosure the device can be carried with a keyring to provide critical data in case of an emergency. The DS1977 can also serve as data shuttle to transport fleet management and vending machine data to an access point for upload into a remote server for further processing.
PAGE 5
DS1977 Figure 2.
PAGE 6
DS1977 Figure 4. 1-WIRE CRC GENERATOR 8 5 4 POLYNOMIAL = X + X + X + 1 st nd 1 STAGE X 0 rd 2 STAGE X 1 th 3 STAGE X 2 th 4 STAGE X 3 th 5 STAGE X 4 th 6 STAGE X 5 th 7 STAGE X 6 8 STAGE X 7 X 8 INPUT DATA MEMORY The memory map of the DS1977 is shown in Figure 5. The 32KB of general-purpose EEPROM are located in pages 0 through 510. The passwords and the Password Control register take 17 bytes of page 511.
PAGE 7
DS1977 Read Access Password This password only applies to the function "Read Memory with Password”. If passwords are enabled (EPW = AAh, see Password Control register), the 64-bit data pattern that the 1-Wire master has to transmit with the command flow is compared to the passwords stored in the DS1977 iButton. The DS1977 delivers the requested data only if the password transmitted by the master was correct or if password checking is not enabled.
PAGE 8
DS1977 passwords, check whether the new password has been successfully installed. See Verify Password command for details. Once enabled, changing the passwords or disabling password checking requires the knowledge of the current full-access password. VERSION REGISTER The DS1977 includes a read-only Version register, which is not a component of the memory map. Therefore, a special command is used to read this register.
PAGE 9
DS1977 WRITING WITH VERIFICATION To write data to the DS1977 , the scratchpad has to be used as intermediate storage. First the master issues the Write Scratchpad command to specify the desired target address, followed by the data to be written to the scratchpad. Under certain conditions (see Write Scratchpad command) the master will receive an inverted CRC16 of the command, address and data at the end of the write scratchpad command sequence.
PAGE 10
DS1977 Regardless of the actual ending offset the master may continue reading data until the end of the scratchpad after which it will receive an inverted CRC16 of the command code, Target Addresses TA1 and TA2, the E/S byte, and the scratchpad data starting at the byte offset, which is determined by the target address. After the CRC is read, the bus master will read logical 1s from the DS1977 until a reset pulse is issued.
PAGE 11
DS1977 Figure 7-1.
PAGE 12
DS1977 Figure 7-2. MEMORY/CONTROL FUNCTION FLOW CHART From Figure 7 1st Part 99h Copy Scrpad. [w/PW] To Figure 7 3rd Part N Y Master TX TA1 (T7:T0), TA2 (T15:T8) Master TX E/S Byte Master TX 64-Bits [Password] NOTE: The strong pullup must be activated within 40µs after the last bit of the password is transmitted. Pullup duration: see tSPUW Master Activates Strong Pullup N ReadAccess Passw.
PAGE 13
DS1977 Figure 7-3. MEMORY/CONTROL FUNCTION FLOW CHART From Figure 7 2nd Part 69h Read Mem. [w/PW] To Figure 7 4th Part N Y Master TX TA1 (T7:T0), TA2 (T15:T8) NOTE: The strong pullup must be activated within 40µs after the last bit of the password is transmitted. Pullup duration: see tSPUR Master TX 64-Bits [Password] To continue reading the next memory page, the strong pullup must be activated within 40µs after the last bit of the CRC16 is read.
PAGE 14
DS1977 Figure 7-4. MEMORY/CONTROL FUNCTION FLOW CHART From Figure 7 3rd Part C3h Verify Password CCh Read Version N Y Y N Master TX TA1 (T7:T0), TA2 (T15:T8) N Address of Password? Y DS1977 sets Memory Address = (T15:T3, 0, 0, 0) Master TX two bytes 00h Master TX Password to verify Master RX two copies of Version Register Master Activates Strong Pullup NOTE: The strong pullup must be activated within 40µs after the last bit of the password is transmitted.
PAGE 15
DS1977 Read Version Command [CCh] This command allows the master to read the chip revision code of the DS1977. After issuing the command code, the master sends two 00h-bytes to access the version register. With the next 16 time slots the master receives two copies of the content of the version register. Additional read-time slots will read logic 1's. Only the upper 3 bits of the version register are valid. The lower 5 bits will all read 0.
PAGE 16
DS1977 Figure 8. HARDWARE CONFIGURATION VPUP SIMPLE BUS MASTER DS1977 1-Wire PORT IRLMS6702 or equivalent SPU RPUP SEE TEXT RX RX DATA TX SPU = Strong Pullup TX RX = Receive Open Drain Port Pin 100 Ω MOSFET TX = Transmit DS2480B BUS MASTER +5V VDD VPP HOST CPU Serial Port serial in serial out POL 1-W RXD NC To 1-Wire data TXD GND DS2480B READ ROM [33H] This command allows the bus master to read the DS1977’s 8-bit family code, unique 48-bit serial number, and 8-bit CRC.
PAGE 17
DS1977 Figure 9-1.
PAGE 18
DS1977 Figure 9-2.
PAGE 19
DS1977 RESUME COMMAND [A5h] The Resume Command function maximizes the data throughput in a multidrop environment. This function checks the status of the RC bit and, if it is set, directly transfers control to the Memory/Control functions, similar to a Skip ROM command. The only way to set the RC bit is through successfully executing the Match ROM, Search ROM or Overdrive Match ROM command. Once the RC bit is set, the device can repeatedly be accessed through the Resume Command function.
PAGE 20
DS1977 Figure 10. INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” After the bus master has released the line it goes into receive mode (RX). Now the 1-Wire bus is pulled to VPUP via the pullup resistor or, in case of a DS2480B driver, by active circuitry. When the threshold VTH is crossed, the DS1977 waits for tPDH and then transmits a Presence Pulse by pulling the line low for tPDL. To detect a presence pulse, the master must test the logical state of the 1-Wire line at tMSP.
PAGE 21
DS1977 Figure 11. READ/WRITE TIMING DIAGRAM (continued) Write-Zero Time Slot tW0L VPUP VIHMASTER VTH VTL VILMAX 0V tF tSLOT RESISTOR ε tREC MASTER Read-Data Time Slot SLAVE-TO-MASTER A read-data time slot begins like a write-one time slot. The voltage on the data line must remain below VTLMIN until the read low time tRL is expired.
PAGE 22
DS1977 devices into a smoother low-bandwidth transition. The slew rate control is specified by the parameter tFPD, which has different values for standard and Overdrive speed. 2) There is additional low-pass filtering in the circuit that detects the falling edge at the beginning of a time slot. This reduces the sensitivity to high-frequency noise. This additional filtering does not apply at Overdrive speed. 3) There is a hysteresis at the low-to-high switching threshold VTH.
PAGE 23
DS1977 Figure 13.
PAGE 24
DS1977 COMMAND-SPECIFIC 1-WIRE COMMUNICATION PROTOCOL—COLOR CODES Master to slave Slave to master Strong Pullup WRITE SCRATCHPAD, REACHING THE END OF THE SCRATCHPAD (CANNOT FAIL) RST PD Select WS TA CRC16\ FF loop WRITE SCRATCHPAD, NOT REACHING THE END OF THE SCRATCHPAD (CANNOT FAIL) RST PD Select WS TA RST PD READ SCRATCHPAD (CANNOT FAIL) RST PD Select RS TA-E/S CRC16\ FF loop COPY SCRATCHPAD WITH PASSWORD (SUCCESS) RST PD Select CPS TA-E/S
PAGE 25
DS1977 VERIFY PASSWORD (SUCCESS) RST PD Select VP TA Password Strong Pullup AA loop VERIFY PASSWORD (FAIL ADDRESS OR PASSWORD) RST PD Select VP TA Password Strong Pullup FF loop READ VERSION (CANNOT FAIL) RST PD Select RV 00h 00h Version Version FF loop COMMUNICATION EXAMPLES The examples in this section demonstrate the use of the memory functions in typical situations. The first example shows how to read the ROM and the version register.
PAGE 26
DS1977 With only a single DS1977 connected to the bus master, the communication is as follows: MASTER MODE Step 1 TX RX TX TX TX Step 2 Step 3 Step 4 DATA (LSB FIRST) (Reset) (Presence) CCh 0Fh C0h TX TX TX 7Fh TX RX TX TX RX RX RX RX (Reset) (Presence) CCh AAh C0h 7Fh 0Fh <16 Bytes> TX RX TX TX (Reset) (Presence) CCh 99h TX TX TX TX C0h 7Fh 0Fh <8 Bytes> (—) RX (Activate Strong Pullup for tPROG) AAh TX RX TX TX TX (Reset) (Presence) CCh C3h C0h TX TX
PAGE 27
DS1977 MASTER MODE DATA (LSB FIRST) TX TX (—) RX TX RX TX TX TX 7Fh (Activate Strong Pullup for tPROG) AAh (Reset) (Presence) CCh 0Fh D0h TX TX TX RX TX TX RX RX RX RX TX RX TX TX 7Fh AAh (Reset) (Presence) CCh AAh D0h 7Fh 10h AAh (Reset) (Presence) CCh 99h TX TX TX TX D0h 7Fh 10h <8 Bytes> (—) RX (Activate Strong Pullup for tPROG) AAh TX RX (Reset) (Presence) Step 5 COMMENTS Password Address) TA2, Target Address = 7FC8h Transmit Full-Access Password Supply Power for Pass
PAGE 28
DS1977 With only a single DS1977 connected to the bus master, the communication is as follows: MASTER MODE Step 1 TX RX TX TX TX TX TX TX RX Step 2 TX TX RX RX RX RX Step 3 Step 4 Step 5 DATA (LSB FIRST) (Reset) (Presence) CCh 0Fh A0h 00h <10 Data Bytes> (Reset) (Presence) CCh AAh A0h 00h 29h <10 Bytes> TX RX TX TX (Reset) (Presence) CCh 99h TX TX TX TX (—) RX A0h 00h 29h (Activate Strong Pullup for tPROG) AAh TX RX TX TX (Reset) (Presence) CCh 69h TX TX TX (—) RX RX (—) RX
PAGE 29
DS1977 REVISION HISTORY REVISION DATE DESCRIPTION 8/09 Added the # sign to the PART number in the Ordering Information table, indicating an RoHS-compliant product. Removed the UL#913 bullet from the Common iButton Features section. 11/09 • Applied EC table note 13 to tW0L. • Deleted ε from the tW1L spec in the EC table. • VTL/VTH clarification: Added to EC table note 4 the text ", which is a function of ...