Abstract: Provided is a wireless time servicing method, device and system. The wireless time servicing method includes: obtaining absolute time information sent by an external clock source; correcting a system time of a master station according to the absolute time information; broadcasting path information to a slave station; receiving feedback from the slave station in response to the path information, calculating a transmission path delay between the master station and the slave station, and storing the transmission path delay in the time information; and sending the time information to the slave station.

Abstract: The disclosure provides example mass-sensing instruments and methods for use thereof. A mass-sensing instrument includes a mass sensor that includes a first terminal and a second terminal. The mass sensor has a natural oscillation frequency configured to correspond to a mass of a deposited material on the mass sensor. The mass-sensing instrument also includes a first driving circuit configured to control a first voltage of the first terminal and a second driving circuit configured to control a second voltage of the second terminal.

Abstract: A timepiece movement includes a stepping motor having a rotor for rotating an indicating hand, and a control unit for rotating the rotor by using a main drive pulse and an auxiliary drive pulse. When the indicating hand is rotated using a detection drive pulse based on the main drive pulse, the control unit determines a reference position of the indicating hand by detecting a rotation state of the rotor.

Abstract: A counting device and a pedometer device is described. The counting device includes: a piezoelectric sensor generating a voltage signal when pressed; a rectifier receiving the voltage signal and rectifying the voltage signal to produce a trigger signal; a non-volatile counter receiving the trigger signal, and including a plurality of non-volatile D flip-flops counting according to the trigger signal and storing count data; a processing module reading the count data and using the count data to generate a counting value; and a wireless communication module transmitting the counting value to an external device. The counting device is powered with electrical energy of the voltage signal generated by the piezoelectric sensor.

Abstract: A circuit device includes an oscillation circuit, a clock signal output circuit that outputs a clock signal based on an output signal from the oscillation circuit, and an output control circuit. The output control circuit includes a counter circuit that performs a counting process on the basis of the output signal from the oscillation circuit, and a count enable signal generation circuit that outputs a count enable signal for the counter circuit. The counter circuit starts the counting process when the count enable signal becomes active, and outputs an output enable signal for the clock signal to the clock signal output circuit on the basis of a result of the counting process.

Abstract: A rotation detection unit configured to detect the condition of rotation of a stepping motor on the basis of an induced signal generated in a drive coil of the stepping motor in a detection period in which the condition of rotation of the stepping motor is detected and a control unit configured to rotationally drive the stepping motor by supplying a drive signal to the drive coil of the stepping motor within the driving period in which the stepping motor is rotationally driven are provided. The driving period and part of the detection period are configured to overlap with each other in a first time interval, and the control unit stops supply of the drive signal to the drive coil of the stepping motor in the first time interval.

Abstract: A voltage determination device includes a reference voltage generation circuit; a determination target voltage line; a first voltage line; a second voltage line; and a switching circuit disposed between the first voltage line and the second voltage line. The switching circuit is provided for performing a switching operation according to a level of the determination target voltage. The voltage determination device includes a determining circuit for determining the level of the determination target voltage, and a control unit is provided for controlling a level of an electric current flowing between the first voltage line and the second voltage line. The control unit controls a resistivity between the switching circuit and the second voltage line so that the level of the electric current is maintained at a specific level when the determining circuit determines the level of the determination target voltage.

Abstract: Method of adjusting the oscillation frequency of a timepiece regulating assembly with no index assembly, formed of a balance and balance spring assembly, to a predetermined oscillation frequency: a particular balance spring assembly is randomly taken from a production of toleranced products; the return torque of said balance spring assembly is measured; a balance is randomly taken from a production of toleranced products; a calculation is made of the theoretical inertia (IT) of said particular balance required to achieve said predetermined oscillation frequency, according to said measured return torque of said balance spring; the real inertia (IR) of said particular balance is measured; by direct action on said particular balance, the inertia of said particular balance is corrected to said calculated theoretical inertia value (IT) in order to obtain said predetermined oscillation frequency for said regulating assembly formed by said particular balance, and by said particular balance spring assembly.

Abstract: A clock movement is provided that contains a constant force device. In accordance with one implementation, the clock movement includes a spiral spring, and a train, having a first kinematic chain arranged to connect a main energy source to a first end of the spiral spring and a second kinematic chain for connecting a time base to a second end of the spiral spring. One of the first and second kinematic chains may contain an adjustment mobile comprising first and second members connected to each other by a friction such that a rotation of one member drives the other member during routine working of the clock movement. One of these members may include an adjustment member having at least one bearing surface arranged such that it is possible to act upon the latter so as to rotate the adjustment member without rotating the other member by dint of friction, in order to adjust the load state of the spiral spring.

Abstract: A rotation detection unit configured to detect the condition of rotation of a stepping motor on the basis of an induced signal generated in a drive coil of the stepping motor in a detection period in which the condition of rotation of the stepping motor is detected and a control unit configured to rotationally drive the stepping motor by supplying a drive signal to the drive coil of the stepping motor within the driving period in which the stepping motor is rotationally driven are provided. The driving period and part of the detection period are configured to overlap with each other in a first time interval, and the control unit stops supply of the drive signal to the drive coil of the stepping motor in the first time interval.

Abstract: The autoregulating circuit regulates the oscillation frequency of an oscillating mechanical system, such as a balance having a balance spring. A piezoelectric element is mounted on the oscillating balance spring to generate an alternating voltage and connected to the autoregulating circuit, which rectifies the alternating voltage and regulates the alternating voltage frequency. The rectified voltage is stored in a capacitor to power the autoregulating circuit. The autoregulating circuit includes an oscillator stage connected to a MEMS resonator for supplying a reference signal, a means for comparing the frequency of the alternating voltage to the reference signal frequency, and a frequency adaptation unit for supplying a frequency adaptation signal to the piezoelectric element according to the result from the comparison means, to regulate the oscillation frequency of the balance. The electronic components of the autoregulating circuit form a single electronic module.

Abstract: A method and apparatus for externally aided self adjusting real time clock have been disclosed. A circuit having a pulse train output is coupled to an adjusting circuit, a real-time clock is coupled to the adjusting circuit, and a proportional integral derivative time processor is coupled to the adjusting circuit, and where the adjusting circuit affects the pulse train output.

Abstract: An integrated circuit (IC), a method of operating the IC and devices incorporating the IC. In one embodiment, the IC includes: (1) a monolithic substrate and (2) a time code receiver supported by the monolithic substrate and configured to receive a timing signal and employ the timing signal to adjust a local oscillator of a real time clock (RTC).

Abstract: A circuit comprises a frequency divider configured to receive an oscillating signal generated by an oscillator and to divide the oscillating signal into a clock signal, wherein the division ratio of the frequency divider is set to a value equal to one of: the integer part of the resonant frequency of the oscillator and the integer part of the resonant frequency of the oscillator plus 1. The circuit further comprises a control element which switchable connects or disconnects a calibration element to alter the frequency of the oscillation signal input to the frequency divider based on a number of oscillations that have transpired in the oscillating signal.

Abstract: An electronic timepiece includes a limiting circuit that is controlled by the rotation detecting circuit and limits output of a locking pulse PL. The electronic timepiece prevents the display of the incorrect current time due to impact, by executing impact detection when rotation is detected, and prevents errant hand operation in a magnetic field by not outputting a locking pulse PL by prohibiting impact detection when non-rotation is detected. The electronic timepiece controls the limiting circuit using a ranking-down storing circuit and if the electronic timepiece employs multi-stage load correction, executes impact detection when regularly occurring non-rotation is detected. Thereby, errant deviation in the display of the current time due to impact is prevented. The electronic timepiece prohibits the impact detection and causes the locking pulse PL not to be output when non-rotation other than those occurring regularly is detected. Thereby, errant hand operation in a magnetic field is prevented.

Abstract: Systems and methods for operating with oscillators configured to produce an oscillating signal having an arbitrary frequency are described. The frequency of the oscillating signal may be shifted to remove its arbitrary nature by application of multiple tuning signals or values to the oscillator. Alternatively, the arbitrary frequency may be accommodated by adjusting operation one or more components of a circuit receiving the oscillating signal.

Abstract: A clock movement is provided that contains a constant force device. In accordance with one implementation, the clock movement includes a spiral spring, and a train, having a first kinematic chain arranged to connect a main energy source to a first end of the spiral spring and a second kinematic chain for connecting a time base to a second end of the spiral spring. One of the first and second kinematic chains may contain an adjustment mobile comprising first and second members connected to each other by a friction such that a rotation of one member drives the other member during routine working of the clock movement. One of these members may include an adjustment member having at least one bearing surface arranged such that it is possible to act upon the latter so as to rotate the adjustment member without rotating the other member by dint of friction, in order to adjust the load state of the spiral spring.

Abstract: An electronic timepiece includes a limiting circuit that is controlled by the rotation detecting circuit and limits output of a locking pulse PL. The electronic timepiece prevents the display of the incorrect current time due to impact, by executing impact detection when rotation is detected, and prevents errant hand operation in a magnetic field by not outputting a locking pulse PL by prohibiting impact detection when non-rotation is detected. The electronic timepiece controls the limiting circuit using a ranking-down storing circuit and if the electronic timepiece employs multi-stage load correction, executes impact detection when regularly occurring non-rotation is detected. Thereby, errant deviation in the display of the current time due to impact is prevented. The electronic timepiece prohibits the impact detection and causes the locking pulse PL not to be output when non-rotation other than those occurring regularly is detected. Thereby, errant hand operation in a magnetic field is prevented.

Abstract: A clock device is provided for generating a real-time clock. The clock device includes a frequency generator, a measuring module, a setting module and a timing module. The frequency generator generates a frequency signal. The measuring module is coupled to the frequency generator for measuring the frequency signal and generating a measuring frequency value. The setting module is coupled to the measuring module for generating an error setting value corresponding to the measuring frequency value. The timing module is coupled to the frequency generator and the setting module for compensating the frequency signal according to the error setting value and generating the real-time clock.

Abstract: A method for correcting time error in an oscillator operated clock according to one aspect of the invention includes at selected times determining at least one of a time error in the clock and a frequency difference between the oscillator and a reference oscillator by detecting a time reference signal. A change in the at least one of the time error and the frequency difference between a first one and a second one of the detecting the time reference signals is determined. A frequency of the oscillator is adjusted so as to substantially cancel a cumulative time error between the second one of the detecting the time reference signal and a selected detecting the time reference signal.

Abstract: The horological movement comprises a regulating device having an oscillation frequency f and an escapement (11, 12) for maintaining the oscillations of the regulating device. The escapement comprises an escape wheel (11) having N teeth. The frequency f is at least equal to about 5 Hz, and the ratio between the number N of teeth and the frequency f is substantially equal to 5.

Abstract: A method for a portable device is disclosed. A reference clock is provided. A first time value and a first index are recording at a first time point. A second index is recorded at a second time point. The first time point and the second time point are counted according to the reference clock. The first index and the second index are calculated. A second time value is set according to the calculating result.

Abstract: A method for a portable device is disclosed. A reference clock is provided. A first time value and a first index are recording at a first time point. A second index is recorded at a second time point. The first time point and the second time point are counted according to the reference clock. The first index and the second index are calculated. A second time value is set according to the calculating result.

Abstract: A method of correcting a real-time clock of an electronic apparatus, notably a mobile telephone, in which the real-time clock operates with a first clock generator which generates a real-time clock while the electronic apparatus operates with a second clock generator which generates a system clock, which method includes the following steps: determining the actual frequency of the real-time clock, determining the ratio Vclock/standard of the actual frequency of the real-time clock to the reference frequency of a standard clock, determining the deviation time of the real-time clock per second from the difference (1?Vclock/standard), determining, on the basis of the deviation time per second, a time difference dt within which the real-time clock is to be corrected by a correction time difference ?t, correcting the real time by ?t after expiration of dt.

Abstract: A frequency divider circuit uses a base counter to frequency divide a clock signal with period T by an integer value N and employs a cyclic rotational select circuit to select among multiple equally phase shifted signals of a multiple phase clock to generate a fractional term P/k where P is variable from 0 to k?1. The counter counts an output clock that corresponds to the output of a multiplexer selecting from among the multiple clock phases. Depending on the desired fractional term, after N counts of the output clock phases of the multiple phase clock are selected glitch free by rotationally selecting a first phase, and skipping either 0, 1, 2 . . . up to k?1 sequential phases to generate fractional terms 0, 1/k, 2/k, 3/k . . . k?1/k, respectively, thus providing frequency division corresponding to N+P/k where P may be varied from 0 to k?1.

Abstract: A method of correcting a real-time clock of an electronic apparatus, notably a mobile telephone, in which the real-time clock operates with a first clock generator which generates a real-time clock while the electronic apparatus operates with a second clock generator which generates a system clock, which method includes the following steps:

Abstract: Accuracy adjustment apparatus for a timepiece has an accuracy adjustment data input control section including a case-mounted switch such as a crown of the timepiece. A crown state detection signal is used to determine the state of the crown. When an accuracy adjustment data input mode is indicated based on the position of the crown, an indicator of the timepiece is driven to provide a visual indication of accuracy adjustment data selectable by operation of the crown. When the proper accuracy adjustment data has been selected, the data is stored to a memory.

Abstract: A data transmission/reception system for wrist-type electronic timepiece. The data transmission/reception system for electronic timepieces comprises a data transmission device for generating data signals, and an electronic timepiece that receives data signals from the data transmission device by utilizing a coil for driving the hands, wherein the electronic timepiece is provided with a timing signal-generating means which generates a timing signal, and the data transmission device is provided with a timing signal-receiving means which receives the timing signals output from said hand-driving coil and transmits data signals in synchronism with the timing signals that are received. The data are transmitted and received in an ordinary hand-moving state without halting the timepiece while the functions are being operated. Therefore, there is no need of adjusting the time after the operation of the functions.

Abstract: A time display is comprised of a low cost low accuracy RC oscillator. A series of pulses derived from this oscillator, for example, with a period of 1 second, is used for controlling a diode. An accurate time-display function of a car radio is also derived from this oscillator. This is possible as the main micro-controller periodically calibrates the low accuracy oscillator using a high accuracy crystal clock. Specifically, it measures the PC oscillator period in order to correct, in the micro-controller, the time issued from the RC oscillator.

Abstract: A real time clock, suitable for use in mobile units in a radiocommunication system, is calibrated during production, and corrects for timing inaccuracies during normal operation. As a result, the accuracy of the real time clock's crystal oscillator is increased economically and efficiently. Frequency error correction is performed by periodically adjusting the frequency of the real time clock by a fixed amount once for every interval of time defined by an adjustment value. The adjustment value is determined by a calibration procedure performed during manufacture of the mobile unit.

Abstract: A device (10) for automatically adjusting a device containing a clock (70) that derives its timing function from the frequency of an alternating current signal on a power line is provided. The device (10) includes a controller (15) that receives user-entered controls for adjusting the clock (70) and generates control signals in response to the user-entered controls. The device also includes a frequency changer (11) that responds to the control signals to increase or decrease the frequency of the alternating current signal applied to the clock (70) so that the clock (70) may be adjusted.

Abstract: A rotating transmission line for use in spectrum up-scaling or down-scaling of signals. The rotating medium is characterized by different velocity gradients, whereby when a signal propagates in such medium, the signal undergoes a Doppler effect as it propagates through the moving medium.

Abstract: A real time clock is arranged to generate output signals indicative of time of day. An oscillating device (101) produces a first clocking signal which is adjusted in response to a calibration value to produce an output clocking signal. A processor (102) re-calculates the calibration value in response to external clocking signals received from a cellular base station for mobile telephones. The clock may be provided within a mobile telephone and the oscillating device may also be used to provide sleep clock signals allowing a high frequency system clock to be de-activated for periods while the telephone is in a stand-by condition.

Abstract: A method and apparatus for adjusting the accuracy of an electronic timepiece that includes an oscillator with a 2.sup.n frequency output, means for reducing the oscillator output frequency to a time keeping frequency, means for counting the time keeping frequency, and means for displaying the time corresponding to the count of the time keeping frequency. The timepiece is initially synchronized with a time standard. After a period of time has elapsed, the timepiece is resynchronized with a time standard and the error E accumulated by the timepiece since the previous synchronization is calculated. The accumulated error, E, is divided by the number of adjustment intervals elapsed since the previous synchronizing of the timepiece, N, to obtain an accuracy adjustment factor. Then, at a specified time interval during each subsequent adjustment interval, the timekeeping frequency is adjusted by the amount of the accuracy adjustment factor to produce a resultant adjustment interval which equals an ideal time period.

Abstract: A manual set operation is described for a timepiece where a single switch is used to select categories and values for setting timekeeping quantities. The timepiece is implemented using a CMOS microcontroller integrated circuit and employs a matrix liquid crystal display to display time and calendar information one character at a time, in a slide-show manner.

Abstract: A commercially available clock IC which is easily influenced by a temperature change or the like is used as it is, thereby easily allowing the clock IC to function as a high precision clock IC. A high precision oscillator is provided separately from a clock circuit as a clock IC. On the basis of a clock signal from the high precision oscillator, a predetermined time, for example, one minute is measured by a high precision clock control circuit. A correction signal is transmitted to the clock circuit as a clock IC from a high precision control circuit every measurement of such a predetermined time, thereby allowing the correcting operation of the time information to be executed. The clock circuit is, consequently, made operative at a precision of the high precision oscillating circuit.

Abstract: To produce a time-base signal for timekeeping, an oscillator circuit generates an oscillator clock signal, which is counted cyclically with a programmable cycle length to establish a time-base cycle. The time-base signal is set and reset once in each time-base cycle. The oscillator clock signal is also counted with a fixed cycle length to establish an adjustment cycle, which is longer than the time-base cycle. In each adjustment cycle, the length of one or more time-base cycles is altered by a total amount determined by adjustment data stored in a non-volatile memory, then the time-base cycle length is restored to its nominal value. The average frequency of the time-base signal can be adjusted by writing appropriate adjustment data in the non-volatile memory.

Abstract: A GPS-based frequency/time source of the present invention provides an accurate, traceable low cost reference. In particular, the GPS-based frequency/time source includes a GPS receiver, a variable frequency oscillator and a micro processor. The GPS receiver receives and produces as output signals GPS information, whereas the variable frequency oscillator has a frequency control input terminal and produces an output frequency signal, and is coupled to the GPS receiver. The micro processor is coupled to receive the output signals produced by the GPS receiver and produces an error signal indicative of a difference in frequency between GPS synchronized frequency and the output frequency signal of the variable frequency oscillator. Circuitry is responsive to the error signal to produce an electronic frequency control signal, which is applied to the frequency control input of the variable frequency oscillator so as to cause the difference in frequency to be reduced.

Abstract: A system and method for controlling time-critical functions by dynamically adjusting the interrupt frequency of a microprocessor. Interrupts are generated at a predetermined frequency. Time-critical functions are then performed in response to the interrupts. The interval is adjusted based on timing data from a substantially accurate source. Where the interval is measured in terms of clock pulses, a non-integer number of pulses per interval is attained by varying the number of pulses per interval so that the average over a number of intervals is equal to the non-integer number of pulses per interval. The interval is further adjusted using a selected damping coefficient to eliminate an underdamped condition.

Abstract: An adjustable vibrations counter (20) and an elapsed time counter and switch (18) that select and adjust one second durations, the adjustment depending on whether the timekeeping rate of a watch or clock is fast or slow. The adjustable vibrations counter provides for an increase or decrease in the number of crystal (12) vibrations that are counted during each adjusted one second duration. The elapsed time counter and switch provides for the number of seconds that are selected for adjustment during each hour or day.A slide switch (22) or other means for changing the number of crystal vibrations that are counted during an adjusted one second duration, thus providing the timekeeping rate regulation. A display (28) of the amount of timekeeping rate adjustment that has been entered into a watch or clock.

Abstract: A device and method provide for an accurate output from a unit, such as an oscillator and/or clock providing an output indicative of frequency and/or time. The device includes a processing section having a microprocessor that develops a model characterizing the performance of the device, including establishing predicted accuracy variations, and the model is then used to correct the unit output. An external reference is used to provide a reference input for updating the model, including updating of predicted variations of the unit, by comparison of the reference input with the unit output. The ability of the model to accurately predict the performance of the unit improves as additional updates are carried out, and this allows the interval between the updates to be lengthened and/or the overall accuracy of the device to be improved. The accuracy of the output is thus adaptively optimized in the presence of systematic and random variations.

Abstract: An integrated circuit for an electronic timepiece includes at least one semiconductor nonvolatile memory device. Reference data can be checked across a pair of output terminals prior to being stored in at least one EPROM to check the accuracy and acceptability of the reference data for driving a motor of the timepiece. The reference data once written into the EPROM serves as control data. Both the reference data and control data are used for controlling at least one function of the timepiece. The control data also can be checked across the output terminals to determine its accuracy and acceptability for driving the motor. Testing of the reference data and control data can be performed on a faster than real time basis.

Abstract: An integrated circuit for an electronic timepiece includes at least one semiconductor nonvolatile memory device. Reference data can be checked across a pair of output terminals prior to being stored in at least one EPROM to check the accuracy and acceptability of the reference data for driving a motor of the timepiece. The reference data once written into the EPROM serves as control data. Both the reference data and control data are used for controlling at least one function of the timepiece. The control data also can be checked across the output terminals to determine its accuracy and acceptability for driving the motor. Testing of the reference data and control data can be performed on a faster than real time basis.

Abstract: A dual selection system for a reference frequency for use in a clock comprising a microcomputer for controlling the whole system and outputting a switching signal and frequency-demultiplying signals. A system oscillator produces an oscillation signal of 4.194304 MHz. A system frequency-demultiplier for frequency-dividing an output of a first buffer to apply a system clock signal to the microcomputer. A clock oscillator produces an oscillation signal of 32.768 KHz, and a clock frequency-demultiplier for frequency-dividing an output of a second buffer applies a clock signal of 1 Hz for clock to the microcomputer.When an option is selected, a system oscillation signal of 4.194304 MHz is selected and frequency-demultiplied by 2.sup.22 to a clock signal of 1 Hz for a clock. When that the option is not selected, the clock oscillation signal of 32.768 KHz is frequency-divided by 2.sup.15 to a clock signal of 1 Hz for the clock.

Abstract: A system to measure time based on the output of a plurality of clocks employs a common oscillator, rather than a frequency synthesizer. Phase differences between a plurality of clocks are measured by mixing the output from each clock with the output of the common oscillator and detecting the zero crossing of each of the resulting beat signals. The zero crossings are counted and used to start and stop time interval counters, which count the time intervals between zero crossings of the beat signals from different clocks. The output of one of the clocks is used to provide a time base. The output of the first clock is input to a divider, and the divided signal used to start the first of the time interval counters. The number of zero crossings of the divided signal are also counted so that the relative frequency of the common oscillator can be determined. The output of the divider can be synchronized with an external clock.

Abstract: Improved atomic clocks and frequency standards of the type where the frequency of an oscillator is stabilized by locking via a phase lock loop to an atomic resonator and where the output of the clock is taken from this oscillator. Protective means are provided to maintain a high accuracy when such clock is exposed to a strong magnetic field. The stabilization is based on two magnetic "C"-fields which are controlled and adjusted to maintain the accuracy of the clock.

Abstract: An atomic clock of the type comprising a quartz oscillator, a tube contaig a material, the atoms of which have an hyperfine spectral transition, control means capable of generating, from the quartz oscillator, a control signal of a frequency that corresponds to the hyperfine spectral transition, and of applying this control signal to the tube to cause interaction between this signal and the atoms of the material contained in the tube, and feedback means that are sensitive to the response of the tube and are adapted to modifying the frequency of the quartz oscillator so as to substantially center the frequency of the control signal on the frequency of the hyperfine spectral transition, wherein the control means are adapted to cyclically generate test signals, the controlled frequency of which is located outside the Ramsey peak.

Abstract: The sidereal clock comprises a digital clock portion having a 60-Hz pulse source operating at line frequency of 60-Hz. It contains a means for periodically changing logic state at the 50/60-Hz select input of the prescale counter so that the digital clock portion is periodically changed during a period equal to 2922 clock pulses from the 60 Hz operation mode to the 50 Hz operation mode for a time interval equal to 40 clock pulses. During this time interval the prescale counter actually registers 6 counts for every 5 pulses received so that the digital clock portion runs fast by a factor of 2930/2922 and measures sidereal time. The means for changing logic state at the 50/60-Hz select input may comprise a ripple counter connected electrically to a plurality of gating circuits of first and second gating integrated circuits and a monostable multivibrator all of which are energized by the DC of the digital clock portion.

Abstract: A local oscillator for a radio receiver includes a voltage controlled oscillator (VCO), a decoder and controller for providing a control voltage to the VCO, an error detector circuit for detecting an error in the frequency of the VCO on the basis of a received signal processed with the oscillating signal from the VCO, a temperature probe and a memory. The local oscillator is initially set up during manufacture by detecting any errors in the frequency at selected temperatures, and storing data in the memory indicative of the control voltage required to compensate for the frequency error for each temperature. In operation the decoder and controller applies the appropriate control voltage to the VCO on the basis of the data stored in the memory relative to the temperature detected by the temperature probe.

Abstract: A microcontroller, software-based time-of-day clock compensates for inaccurate oscillator frequency by periodically correcting the time-of-day value using a calibration offset measured by manufacturing test equipment and permanently stored in nonvolatile memory. A high degree of time keeping accuracy is achieved without the use of trimming capacitors or presorted piezoelectric crystals in the oscillator. Furthermore, frequency error compensation is incorporated into the microcontroller system without requiring a significant amount of processing time overhead.