DS1678 Maxim Integrated Products, DS1678 Datasheet
DS1678
Specifications of DS1678
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DS1678 Summary of contents
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... SOIC (208-mil) Package dimension information can be found at: http://www.maxim-ic.com/TechSupport/PackInfo.htm PIN DESCRIPTION V - Battery Supply BAT X1 - Crystal Input X2 - Crystal Output - Interrupt Input/Output INT GND - Ground SDA - 2-wire Input/Output SCL - 2-wire Clock Input V - +5V Supply CC TYPICAL OPERATING CIRCUIT DS1678 Vcc INT SCL SDA 100101 ...
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... RTC equals the value in the RTC alarm register and the duration interval select (DISx) bits are both set to zeros. The DS1678 operates as a slave device on the 2-wire serial bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. All data is transferred to and from the DS1678 most significant bit (MSB) first ...
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The block diagram in Figure 1 shows the main elements of the RTC event recorder. The device has four major components: 1) 64-bit RTC and control block, 2) 32-byte user NV RAM, 3) 2048 bytes of event log memory (1024 ...
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... Communication with the DS1678 can take place only when connected to a +5V supply. V – Battery input for standard lithium cell or other energy source. All functions of the DS1678 with BAT the exception of the serial interface circuitry are powered by V powered by V when V ...
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... The pin can also be used as an output when the DS1678 is not in an event logging mission. The INT pin will become an output and generate an alarm interrupt if the DISx bits are both set to zero and the RTC reaches the preset value in the alarm register ...
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... Since the 2-wire bus only has the capability to use one byte addressing, the DS1678 utilizes the data port to access the 2048 bytes of event log memory. The address that the next data will be written to is stored in the address pointer registers LSB (3Fh) and MSB (40h) ...
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Entering a value greater than 07FFh will result in the address location associated with the value of the lowest 11 bits of the address. The RTC and control registers (See Figure 2a for more detail.) are located in the main ...
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... DS1678 RTC AND CONTROL PAGE Figure 2a ADDRESS BIT 7 BIT 12/ YEAR 07 10 CENTURY SECONDS ALARM MINUTES ALARM 0A MH 12/ CLR MEM 0F 0 CLR ↓ SECONDS MINUTES 0 12/ YEAR 37 10 CENTURY 38 Event 0 Elapsed Time from last Event Counter LSB 39 Event 0 Elapsed Time from last Event Counter MSB ...
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... Event 1024 Elapsed Time from Last Event Counter MSB EVENT LOGGING When the DS1678 event logging function is enabled, the device is said “event log mission” until the event logging is stopped. An event can be triggered one of three ways depending on the settings of the TRx bits in the control register ...
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... Figure 8). The first option is to enable the rollover feature of the DS1678. This is accomplished by setting the rollover bit (bit 3 of the control register When the rollover feature is enabled, new data is written over previous data, starting with the start time stamp register new mission is starting ...
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... BCD format and are year 2000-compliant. The DS1678 can run in either 12-hour or 24-hour mode. Bit 6 of the hour’s register 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 one being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20– ...
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... When the ME bit is set to logic 0, the DS1678 will wait until written to the MIP bit via the 2-wire interface to start the mission. When the MIP bit is written the ME bit will be set to a one, the ...
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CLR - Clear Enable – This bit enables the memory to be cleared. When this bit is set to a one and the clear memory (CM) bit in the status register is subsequently written the event log ...
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... The Counter will Increment Every Hour RO - Roll-Over – This bit determines whether the datalog function of the DS1678 rolls over or stops writing data to the event log memory if the event log memory is completely filled set the event log memory will “roll over” after all 2048 bytes in the event log memory have been used. In other ...
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Likewise, subsequent samples will increment through the event log registers, overwriting their data. The event 0 elapsed time from last event bytes will have the elapsed time since the last event in ...
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... MIP - Mission in Progress – This bit indicates the sampling status of the DS1678. If MIP is logic 1, the device is currently on a “mission” in which it is operating in the event logging mode. The MIP bit is changed to logic 1 immediately following the activation of the register contains order to immediately start an event logging mission via the 2-wire bus can be written into the MIP bit and a 1 will automatically be written into the ME bit of the control register ...
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... As a first security measure, the event log memory is read-only from the perspective of the end user. The DS1678 can write the data into these memory banks, but the end user cannot write data to individual registers. This prevents an unscrupulous intermediary from writing false data to the DS1678. The end user, however, can clear the contents of the event log memory ...
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... START and STOP conditions. The DS1678 operates as a slave on the 2-wire bus. Connections to the bus are made via the open-drain I/O lines SDA and SCL. The following bus protocol has been defined (See Figure 3): § Data transfer may be initiated only when the bus is not busy. ...
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... The address byte contains the 7- bit DS1678 address, which is 1001010, followed by the direction bit ( which is 0. The second byte from the master is the register address. This sets the register pointer. If the write is being done to set the register pointer, a STOP or repeated START may then be sent by the master ...
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ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the ...
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AC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL SCL Clock Frequency Bus Free Time Between a STOP and START Condition Hold Time (Repeated) t START Condition. LOW Period of SCL HIGH Period of SCL Set-Up Time for a t Repeated START Data Hold ...
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... SERIAL COMMUNICATION WITH DS1678 Figure 4 W rite vic rite tio fro rre tio ltip fro rre tio fro tio 2-WIRE COMMUNICATION TIMING DIAGRAM Figure 5 SDA SCL t H D:STA t H D:D AT STOP START yte yte ific yte HIG H SU :ST A SU:D AT ...
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EVENT RECOGNITION TIMING DIAGRAM Figure ven ven ven / ...
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START MISSION FLOW CHART Figure 7 Start via Computer no Mem Clr =1 yes Write the MIP bit The ME bit is Automatically Written Time/Date Stamp is Written ETC Starts Incrementing EC is Incremented ...
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ROLL OVER FLOW CHART Figure Incremented INT Input Activated yes Memory Full yes Rollover Enable = 1 yes ETC Written to Event 0 and Time/Date Stamp is Written ETC is Cleared no Continue to Monitor Input no ...
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NOTES: 1. After this period, the first clock pulse is generated device must initially provide a hold time of at least 300ns for the SDA signal in order to bridge the undefined region of the falling edge of ...