DS1921H/Z Maxim Integrated Products, DS1921H/Z Datasheet
DS1921H/Z
Related parts for DS1921H/Z
DS1921H/Z Summary of contents
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... All dimensions are shown in millimeters. ORDERING INFORMATION DS1921H-F5 +15°C to +46°C DS1921Z-F5 -5°C to +26°C EXAMPLES OF ACCESSORIES DS9096P Self-Stick Adhesive Pad DS9101 Multipurpose Clip DS9093RA Mounting Lock Ring DS9093A Snap-In Fob DS9092 iButton Probe DS1921H/Z © 1993 16.25 21 17.35 ® F5 iButton F5 iButton 091202 ...
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... OVERVIEW The block diagram in Figure 1 shows the relationships between the major control and memory sections of the DS1921H/Z. The device has seven main data components: 1) 64-bit lasered ROM; 2) 256-bit scratch- pad; 3) 4096-bit general-purpose SRAM; 4) 256-bit register page of timekeeping, control, and counter registers bytes of alarm time stamp and duration logging memory; 6) 128 bytes of histogram mem- ory ...
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... DS1921H/Z BLOCK DIAGRAM Figure 1 1-Wire IO Port 32.768kHz Oscillator Temperature Sensor 3V Lithium PARASITE POWER The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry “steals” power when- ever the IO input is high. IO will provide sufficient power as long as the specified timing and voltage re- quirements are met ...
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HIERARCHICAL STRUCTURE FOR 1-Wire PROTOCOL Figure 2 Bus Master Command Level: 1-Wire ROM Function Commands DS1921-Specific Memory Function Commands 64-BIT LASERED ROM Figure 3 MSB 8-Bit 12-Bit Temperature CRC Code Range Code MSB LSB MSB DEVICE TEMP. RANGE (°C) DS1921H-F5 ...
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... X MEMORY The memory map of the DS1921H/Z is shown in Figure 5. The 4096-bit general-purpose SRAM make up pages 0 through 15. The timekeeping, control, and counter registers fill page 16, called Register Page (see Figure 6). Pages are assigned to storing the alarm time stamps and durations. The temperature histogram bins begin at page 64 and use up to four pages ...
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... DS1921H/Z REGISTER PAGE MAP Figure 6 ADDRESS RANGE ACCESS TYPE* 0200h to 0206h R/W; R** 0207h to 020Ah R/W; R** 020Bh R/W; R** 020Ch R/W; R** 020Dh R/W; R** 020Eh R/W; R** 020Fh to 0210h 0211h 0212h to 0213h R/W; R** 0214h R/W; R/W 0215h to 0219h 021Ah to 021Ch 021Dh to 021Fh *The first entry in column ACCESS TYPE is valid between missions. The second entry shows the applicable access type while a mission is in progress ...
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... In the 12-hour mode, bit 5 is the AM/PM bit with logic 1 being PM. In the 24-hour mode, bit 5 is the 20- hour bit ( hours). To distinguish between the days of the week the DS1921H/Z includes a counter with a range from The assignment of counter value to the day of week is arbitrary. Typically, the number 1 is assigned to a Sunday (U ...
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... CONTROL REGISTER The DS1921H/Z is set up for its operation by writing appropriate data to its special function registers that are located in the register page. Several functions that are controlled by a single bit only are combined into a single byte called Control Register (address 20Eh). This register can be read and written. If the device is programmed for a mission, writing to the Control Register will, at the first attempt, end the mission, but not overwrite any settings ...
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... For a typical mission, the Mission Start Delay mission is too long for a single DS1921H/Z to store all temperature readings at the selected sample rate, one can use several devices and set the Mission Start Delay for the second device to start recording as soon as the memory of the first device is full ...
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... EM bit is also 0. The memory has to be cleared in order for a mission to start this bit reads 1 the DS1921H/Z has been set up for a mission and this mission is still in progress. A mission is started if the EM bit of the Control Register (address 20Eh and a non-zero value is written to the Sample Rate Register, address 20Dh ...
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... TEMPERATURE LOGGING AND HISTOGRAM Once setup for a mission, the DS1921H/Z logs the temperature measurements simultaneously byte after byte in the datalog memory as well as in histogram form in the histogram memory. The datalog memory is able to store 2048 temperature values measured at equidistant time points. The first temperature value of a mission is written to address location 1000h of the datalog memory, the second value to address location 1001h and so on ...
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... There are two alternatives to the way the DS1921H/Z will behave after the 2048 bytes of datalog memory is filled with data. The user can program the device to either stop any further recording (disable rollover) or overwrite the previously recorded data (enable rollover), one byte at a time, starting again at address ...
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... The DS1921H/Z can log high and low durations. The tolerance band is specified by means of the Temperature Alarm Threshold Registers, addresses 20Bh and 20Ch in the register page ...
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... This procedure is called missioning. First of all, DS1921H/Z needs to have its RTC set to valid time and date. This reference time may be UTC (also called GMT, Greenwich Mean Time) or any other time standard that was chosen for the application ...
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... Only) WRITING WITH VERIFICATION To write data to the DS1921H/Z, 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. In the next step, the master sends the Read Scratchpad command to read the scratchpad and to verify data integrity ...
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... The Memory Function Flow Chart (Figure 10) describes the protocols necessary for accessing the memory and the special function registers of the DS1921H/Z. An example on how to use these and other functions to set up the DS1921H/Z for a mission is included at the end of this document, preceding the Electrical Characteristics section. The communication between master and DS1921H/Z takes place either at regular speed (default Overdrive Speed ( ...
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MEMORY FUNCTION FLOW CHART Figure 10-1 Master TX Memory or Control Fkt. Command Scratchpad DS1921 sets EMCLR = 0 Master TX TA1 (T7:T0), TA2 (T15:T8) DS1921 sets Scratch- pad Offset = (T4:T0) and Clears (PF, AA) Master TX Data Byte ...
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MEMORY FUNCTION FLOW CHART Figure 10-2 From Figure Part Scratchpad DS1921 sets EMCLR = 0 Master TX TA1 (T7:T0), TA2 (T15:T8) Master TX E/S Byte Authorization Code Match DS1921 Copies Scratchpad Data to Memory ...
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MEMORY FUNCTION FLOW CHART Figure 10-3 From Figure Part Decision made by DS1921 Decision made by Master To Figure Part A5H Read Mem. w/CRC Y DS1921 sets EMCLR = 0 Master TX TA1 (T7:T0), ...
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MEMORY FUNCTION FLOW CHART Figure 10-4 From Figure Part Memory EMCLR = 1? DS1921 clears Mission Time Stamp, Mission Samples Counter, Mission Start Delay, Sample Rate Register DS1921 clears Alarm Time Stamps and Durations DS1921 clears Histogram ...
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... The command works essentially the same way as the simple Read Memory, except for the 16-bit CRC that the DS1921H/Z generates and transmits following the last data byte of a memory page. ...
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... DS1921H/Z and CRC16s at page boundaries until a reset pulse is issued. The Read Memory with CRC command sequence can be ended at any point by issuing a reset pulse. Clear Memory [3Ch] The Clear Memory command is used to clear the Sample Rate, Mission Start Delay, Mission Time Stamp, and Mission Samples Counter in the register page and the Temperature Alarm Memory and the Temperature Histogram Memory ...
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... With the DS1921H/Z the bus must be left low for no longer than 15.2µs at Overdrive speed to ensure that none of the slave devices on the 1-Wire bus performs a reset. Despite of its limited compliance, the DS1921H/Z will communicate properly when used in conjunction with a DS2480B 1- Wire driver and serial port adapters that are based on this driver chip ...
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... CRC. This command can only be used if there is a single DS1921H/Z on the bus. If more than one slave is present on the bus, a data collision will occur when all slaves try to transmit at the same time (open drain will produce a wired-AND result). The resultant family code and temperature range code plus 36-bit serial number will result in a mismatch of the CRC ...
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ROM FUNCTIONS FLOW CHART Figure 12-1 From Memory Functions Flow Chart (Figure 10) 33H N Read ROM? Y DS1921 TX 1) Family Code Master TX Bit 0 1 Byte DS1921 TX 1) Temp. Range Master TX Bit 1 Pattern and ...
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ROM FUNCTIONS FLOW CHART Figure 12-2 To Figure Part From Figure Part From Figure Part To Figure Part N CCH 3CH Skip Overdrive ROM? Skip ROM? Y ...
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... The initialization sequence required to begin any communication with the DS1921H/Z is shown in Figure 13. A Reset Pulse followed by a Presence Pulse indicates the DS1921H/Z is ready to receive data, given the correct ROM and memory function command mixed population network, the reset low time t needs to be long enough for the slowest 1-Wire slave device to recognize reset pulse. With the DS1921H/Z this duration is 480µ ...
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... DS1921H/Z starts its internal time base. The tolerance of the slave time TL base creates a slave-sampling window that stretches from t at the sampling point determines whether the DS1921H/Z decodes the time slot For reliable communication the voltage has to be either below the V the entire sampling window. ...
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... As the voltage on the 1-Wire line falls below the threshold V starts its internal time base. The master pull-down time (t the setup time t , after which the DS1921H/Z delivers a bit to its 1-Wire port. When transmitting a 0, the SU DS1921H/Z will hold the data line low for t data line low at all ...
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... V CRC GENERATION With the DS1921H/Z there are two different types of Cyclic Redundancy Checks (CRCs). One CRC is an 8-bit type and is stored in the most significant byte of the 64-bit ROM. The bus master can compute a CRC value from the first 56 bits of the 64-bit ROM and compare it to the value stored within the DS1921H/Z to determine if the ROM data has been received error-free ...
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CRC-16 HARDWARE DESCRIPTION AND POLYNOMIAL Figure STAGE STAGE STAGE STAGE STAGE Polynomial = ...
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... Assumption: The previous mission has come to an end. To end an ongoing mission one may, for example, perform a sequence as in step 1 or write the MIP bit in the Status Register to 0. The preparation of a DS1921H/Z for a mission including the start of the mission requires up to four steps: Step 1: set the RTC (if it needs to be adjusted) ...
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... Set the EMCLR bit to 1, enable the RTC and then execute the Clear Memory command. This results in the following data to be written to the Status Register: Address: 20Eh Data: 40h With only a single DS1921H/Z connected to the bus master, the communication of step follows: MASTER MODE ...
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... Writing through address locations 20Fh to 211h is faster than accessing the Mission Start Delay Register in a separate cycle. The write attempt has no effect on the contents of these registers. With only a single DS1921H/Z connected to the bus master, the communication of step follows: MASTER MODE ...
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... DS1921Z device. The sample rate is once every 10 minutes, allowing the mission to last days. This results in the following data to be written to the special function registers: Address: 20Bh Data: 2Ch With only a single DS1921H/Z connected to the bus master, the communication of step follows: MASTER MODE ...
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PHYSICAL SPECIFICATION Size Weight Humidity Altitude Safety ABSOLUTE MAXIMUM RATINGS* IO Voltage to GND IO sink current Temperature Range DS1921H, DS1921Z Junction Temperature Storage Temperature Range * This is a stress rating only and functional operation of the device at ...
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PARAMETER SYMBOL IO pin, 1-Wire Reset, Presence Detect Cycle Reset Low Time t RSTL Presence Detect High t PDH Time Presence Detect Low t PDL Time Presence Detect t MSP Sample Time IO pin, 1-Wire Write Write-0 Low Time t ...
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... DS1921H/Z Values Standard Speed Overdrive Speed min max min 65µs (undef.) 8µs 540µs 640µs 48µs 15µs 60µs 1.1µ ...
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RTC FREQUENCY DEVIATION vs. TEMPERATURE -25 -50 -75 -100 -125 -150 -175 -200 -40 -30 -20 -10 MINIMUM PRODUCT LIFETIME vs. TEMPERATURE Every Minute No Samples 11.00 10.00 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 ...
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MINIMUM PRODUCT LIFETIME vs. SAMPLE RATE -5°C 12.00 11.00 10.00 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1. °C 26°C 37°C 10 100 Minutes between Samples 46°C 1000 ...