DS2422 Maxim, DS2422 Datasheet
DS2422
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DS2422 Summary of contents
Page 1
... Without external ADC, the DS2422 functions as a temperature logger only. The DS2422 measures the temperature and/or reads the ADC at a user-defined rate. A total of 8192 8-bit readings or 4096 16-bit readings taken at equidistant intervals ranging from 1s 273hrs can be stored. APPLICATIONS ...
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... Lead Temperature (soldering, 10s) Soldering Temperature (reflow) Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied ...
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PARAMETER SYMBOL I/O Pin, 1-Wire Write Write-0 Low Time t W0L (Notes 1, 14) Write-1 Low Time t W1L (Notes 1, 14) I/O Pin, 1-Wire Read Read Low Time t RL (Notes 1, 15) Read Sample Time t MSR (Notes ...
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... HY has been previously reached The actual respectively W0LMAX F to the input high threshold RLMAX F DS2422 VALUES STANDARD SPEED OVERDRIVE SPEED MIN MAX MIN 1) 65µs (undef.) 9.5µs 690µs 720µs 70µs 15µs 63.5µs 2µs 60µs 287µ ...
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... Application Note 2810. These graphs assume 11-bit temperature conversion. The accuracy can be improved further through software correction, as described in Application Note 2810. DS2422 Temperature Accuracy at 3V Temperature (°C) Min. ± 0.1°C uncertainty Max. ± ...
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... Not connected DESCRIPTION The DS2422 temperature/data logger combines the core functions of a fully featured data logger in a single chip. It includes a temperature sensor, RTC, memory, 1-Wire interface, and serial interface for an analog-to-digital converter (ADC) as well as control circuitry for a charge pump. The ADC and the charge pump are peripherals that can be added to build application-specific data loggers ...
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... SCLK. The DS2422 will activate its alarm output if the measured temperature or serial-input data reaches a user-programmed high or low alarm threshold. This alarm then can be used to shut down the equipment and enforce a service call. In contrast to microprocessor-based data loggers, the DS2422 does not require any firmware development ...
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... The block diagram in Figure 3 shows the relationships between the major control and memory sections of the DS2422. The device has six main data components: 1) 64-bit lasered ROM, 2) 256-bit scratchpad, 3) 512-byte general-purpose SRAM, 4) two 256-bit register pages of timekeeping, control, status, and counter registers and passwords bytes of calibration memory, and 6) 8192 bytes of data-logging memory ...
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... ROM may still be read. 64-BIT LASERED ROM Each DS2422 contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code. The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. See Figure 5 for details. The ...
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... STAGE STAGE STAGE STAGE Figure 7. DS2422 Memory Map 32-Byte Intermediate Storage Scratchpad ADDRESS 0000H to 32-Byte General-Purpose SRAM (R/W) 001FH 0020H to General-Purpose SRAM (R/W) 01FFH 0200H to 32-Byte Register Page 1 021FH 0220H to 32-Byte Register Page 2 023FH 0240H to Calibration Memory Page 1 (R/W) ...
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... MEMORY The memory map of the DS2422 is shown in Figure 7. The 512 bytes general-purpose SRAM are located in pages 0 through 15. The various registers to set up and control the device fill page 16 and 17, called Register Pages 1 and 2 (details in Figure 8). Pages 18 and 19 provide storage space for calibration data. They can alternatively be used as extension of the general-purpose memory. The Trim Register Page holds registers that are used to tune the timing of the serial data interface and to trim the on-chip temperature converter. The " ...
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... The RTC of the DS2422 can run in either 12-hour or 24-hour mode. Bit 6 of the Hours Register (address 202h) is defined as the 12- or 24-hour mode select bit. When high, the 12-hour mode is selected. 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). The CENT bit, bit 7 of the Months Register, can be written by the user ...
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... It is important that the user sets the EHSS bit accordingly while setting the Sample Rate register. Writing a sample rate of 0000h results in a sample rate = 0001h, causing the DS2422 to log either every minute or every second depending upon the state of the EHSS bit. ...
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... B7 B6 020Fh B15 B14 During a mission, if data logging from the serial input is enabled, the HIGH byte (B15 to B8) is always recorded. The LOW byte (B7 to B0) is only recorded if the DS2422 is set up for 16-bit logging of serial input data CPW SCH B15 B14 B13 B12 ...
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... The algorithm to convert the digital reading from the serial interface into a physical unit depends on the circuit that provides the data to the DS2422. This algorithm needs to be reversed when calculating values for the alarm threshold registers that are associated to the serial data input. The registers for data alarm thresholds are located at address 020Ah (Low Alarm) and 020B (High Alarm) ...
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Register Details BIT DESCRIPTION EDLA: Enable Data Low Alarm EDHA: Enable Data High Alarm REAL-TIME CLOCK CONTROL To minimize the power consumption of a battery-operated datalogger, the RTC oscillator should be turned off when device is not in use. The ...
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... The settings in the Mission Control Register determine whether temperature and/or external data is logged, which format ( bits used and whether old data may be overwritten by new data, once the datalog memory is full. An additional control bit can be set to tell the DS2422 to wait with logging data until a temperature alarm is encountered. ...
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... The information in the general status register tells the host computer whether a mission-related command was executed successfully. Individual status bits indicate whether the DS2422 is performing a mission, waiting for a temperature alarm to trigger the logging of data or whether the data from the latest mission has been cleared. ...
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... During a mission, there is only read access to these registers. For a typical mission, the Mission Start Delay mission is too long for a single DS2422 to store all 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, and so on ...
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... The Device Samples Counter is similar to the Mission Samples Counter. During a mission this counter increments whenever the DS2422 wakes up to measure and log data and when the device is testing for a temperature alarm in SUTA mode. Between missions the counter increments whenever the Forced Conversion command is executed. ...
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... The Full Access Password needs to be transmitted exactly in the sequence FP0, FP1… FP62, FP63. It will affect the functions “Read Memory with CRC”, “Copy Scratchpad”, “Clear Memory”, “Start Mission”, and “Stop Mission”. The DS2422 executes the command only if the password transmitted by the master was correct or if password checking is not enabled. ...
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... DATALOG MEMORY USAGE Once setup for a mission, the DS2422 logs the temperature measurements and/or external data at equidistant time points entry after entry in its datalog memory. The datalog memory is able to store 8192 entries in 8-bit format or 4096 entries in 16-bit format (Figure 10A). If temperature as well as external data is logged, both in the same format, the memory is split into two equal sections that can store 4096 8-bit entries or 2048 16-bit entries (Figure 10B) ...
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... There are two alternatives to the way the DS2422 behaves after the 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 “ ...
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... This procedure is called missioning. First of all, DS2422 needs to have its RTC set to valid time and date. This reference time may be the local time, or, when used inside of a mobile unit, UTC (also called GMT, Greenwich Mean Time) or any other time standard that was agreed upon ...
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... The general-purpose memory operates independently of the other memory sections and is not write-protected during a mission. All memory of the DS2422 can be read at any time, e. g., to watch the progress of a mission. Attempts to read the passwords will read 00h bytes instead of the data that is stored in the password registers. ...
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... CRC16 of the command code, Target Addresses TA1 and TA2, the E/S byte, and the scratchpad data starting at the target address. After the CRC is read, the bus master will read logical 1s from the DS2422 until a reset pulse is issued ...
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... CRC generator and then shifting in the contents of the data memory page. After the 16-bit CRC of the last page is read, the bus master will receive logical 1s from the DS2422 until a reset pulse is issued. The Read Memory with CRC command sequence can be ended at any point by issuing a reset pulse. ...
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... Figure 12-1. Memory/Control Function Flow Chart Master TX Memory or Control Fkt. Command 0FH Write Scratchpad Master TX TA1 (T7:T0) Master TX TA2 (T15:T8) DS2422 sets Scratch- pad Offset = (T4:T0) and Clears (PF, AA) Master TX Data Byte to Scratchpad Offset DS2422 sets (E4:E0) = Scratchpad Offset Master TX Reset? DS2422 Incre- N ments Scratch- ...
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... Y N Authorization Code Match DS2422 Copies Scratchpad Data to Memory Master RX "1"s Copying Finished N Y DS2422 TX "0" Y Master TX Reset? N DS2422 TX "1" Master TX Reset Figure Part Authorization Code Master RX "1"s N Master TX Reset? Y From Figure 12 ...
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... To Figure Part 69H Read Mem. [w/PW]&CRC Y Master TX TA1 (T7:T0), TA2 (T15:T8) Master TX 64-Bits [Password] Password Accepted? Y DS2422 sets Memory Address = (T15:T0) Master RX Data Byte from Memory Address Y Master TX Reset? N End of Page? Y Master RX CRC16 of Command, Address, Data st (1 Pass); CRC16 of Data (Subsequent Passes) ...
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... Figure 12 55H th 5 Part N Forced Conversion? Y Master TX FFh dummy byte Y Mission in Progress? N DS2422 Performs a Temp. Conversion DS2422 copies Result to Address 020C/Dh DS2422 Reads Serial Data Interface DS2422 copies Result to Address 020E/Fh N Master TX Reset? Y From Figure Part ...
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... Master TX Reset? To Figure Part Y N Mission Start Delay Process Start Delay Counter = 0? N DS2422 Waits for 1 Minute DS2422 decrements Start Delay Counter SUTA = 1? Y DS2422 Sets WFTA=1 DS2422 Waits One Sample Period Y MIP = 0? N DS2422 Performs 8-bit Temp. Conversion Temp. ...
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... See Memory Access Conflicts for details. START MISSION WITH PASSWORD [CCh] The DS2422 uses a control function command to start a mission. A new mission can only be started if the previous mission has been ended and the memory has been cleared. After the command code, the master must transmit the 64-bit full-access password followed by a FFh dummy byte ...
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... Note that the DS2422 does not quite meet the full 16µs maximum low time of the normal 1-Wire bus Overdrive timing. With the DS2422 the bus must be left low for no longer than 12µs at Overdrive to ensure that no DS2422 on the 1-Wire INDICATION OF Wait 0 ...
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... 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 DS2422 is on the bus and is ready to operate. For more details, see the 1-Wire Signaling section. ...
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... The DS2422 will respond to the conditional search if one of the five alarm flags of the Alarm Status Register (address 0214h) reads 1. The data and temperature alarm will only occur if enabled (see Temperature Sensor Alarm and Serial Input Alarm) ...
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... The Overdrive Match ROM command followed by a 64-bit ROM sequence transmitted at Overdrive Speed allows the bus master to address a specific DS2422 on a multidrop bus and to simultaneously set it in Overdrive mode. Only the DS2422 that exactly matches the 64-bit ROM sequence will respond to the subsequent memory/control function command ...
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... Flow Chart (Figure 12 From Figure 14 Figure 14 ECh N Cond. Search Command Condition Met? Y DS2422 TX Bit 0 DS2422 TX Bit 0 Master TX Bit 0 N Bit 0 Match DS2422 TX Bit 1 DS2422 TX Bit 1 Master TX Bit 1 N Bit 1 Match DS2422 TX Bit 63 DS2422 TX Bit 63 ...
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Figure 14-2. ROM Functions Flow Chart st To Figure 14, 1 Part From Figure Part CCh N Skip ROM Command From Figure Part To Figure Part A5h ...
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... Overdrive speed to accommodate other 1-Wire devices. Read/Write Time Slots Data communication with the DS2422 takes place in time slots, which carry a single bit each. Write time slots transport data from bus master to slave. Read time slots transfer data from slave to master. The definitions of the write and read time slots are illustrated in Figure 16 ...
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... RL line low; its internal timing generator determines when this pulldown ends and the voltage starts rising again. When responding with a 1, the DS2422 will not hold the data line low at all, and the voltage starts rising as soon as t over. is expired. For most reliable communication the voltage on the data ...
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... 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 DS2422 to determine if the ROM data has been received error-free. The equivalent polynomial function of this CRC is: X received in the true (non-inverted) form ...
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... With the Write Scratchpad command the CRC is generated by first clearing the CRC generator and then shifting in the command code, the Target Addresses TA1 and TA2 and all the data bytes. The DS2422 will transmit this CRC only if the data bytes written to the scratchpad include scratchpad ending offset 11111b. The data may start at any location within the scratchpad ...
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COMMAND-SPECIFIC 1-Wire COMMUNICATION PROTOCOL—LEGEND SYMBOL RST 1-Wire Reset Pulse generated by master PD 1-Wire Presence Pulse generated by slave Select Command and data to satisfy the ROM function protocol WS Command "Write Scratchpad" RS Command "Read Scratchpad" CPS Command "Copy ...
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COPY SCRATCHPAD WITH PASSWORD (SUCCESS) RST PD Select CPS COPY SCRATCHPAD WITH PASSWORD (INVALID TA-E/S OR PASSWORD) RST PD Select CPS READ MEMORY WITH PASSWORD & CRC (SUCCESS) RST PD Select RMC READ MEMORY WITH PASSWORD & CRC (INVALID PASSWORD ...
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... Step 1: clear the data of the previous mission Step 2: write the setup data to register page 1 Step 3: start the mission STEP 1 Clear the previous mission. With only a single DS2422 connected to the bus master, the communication of step 1 looks like this: MASTER MODE ...
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... General Mission Parameters (e. g., channels to log and logging format, rollover, start mode) Mission Start Delay The following data will setup the DS2422 for a mission that logs temperature using 8-bit format. Such a mission could last days until the 8192-byte datalog memory is full. ADDRESS ...
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... STEP 3 Start the new mission. With only a single DS2422 connected to the bus master, the communication of step 3 looks like this: MASTER MODE step 3 was successful, the MIP bit in the General Status Register will be 1, the MEMCLR bit will be 0 and the mission start delay will count down ...
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... The Maxim logo is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Dallas Semiconductor DESCRIPTION specification from 0.6V to 0.7V. OLMAX . W0L spec in the EC table. W1L specifications without notice at any time. © 2010 Maxim Integrated Products Corporation. DS2422 PAGES CHANGED — 13, 16, 24, 33 17, 25 ...