CN203289406U - Real-time clock compensation apparatus - Google Patents
Real-time clock compensation apparatus Download PDFInfo
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- CN203289406U CN203289406U CN2013203083736U CN201320308373U CN203289406U CN 203289406 U CN203289406 U CN 203289406U CN 2013203083736 U CN2013203083736 U CN 2013203083736U CN 201320308373 U CN201320308373 U CN 201320308373U CN 203289406 U CN203289406 U CN 203289406U
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Abstract
The utility model discloses a real-time clock compensation apparatus comprising an oscillation crystal, an adjustable capacitance array, a register assembly, a data processing unit, a decoder, a capacitance adjusting unit and a frequency modulator, wherein the register assembly comprises a temperature-measurement register, a drift coefficient register, a top temperature register and a top offset register; the data processing unit is connected with the register assembly; the capacitance adjusting unit is respectively connected with the decoder and the adjustable capacitance array; the adjustable capacitance array is connected with the oscillation crystal; and the frequency modulator is respectively connected with the decoder and the oscillation crystal. The real-time clock compensation apparatus provided by the utility model can compensate a real-time clock, so that measurement precision is raised, compensable scope is wide, testing temperature points are few, precision is high and testing cost of a chip is effectively reduced.
Description
Technical field
The utility model relates to real-time clock, more specifically, is a kind of real-time clock compensation arrangement.
Background technology
real-time clock (Real_Time Clock, RTC) most important function is to provide calendar function, in embedded system, usually provide reliable system time with RTC, while comprising, minute, second and year, month, day etc., the elements such as the oscillating crystal of the external 32.788KHz of common RTC needs and matching capacitance, because crystal oscillation frequency can be the conic section drift with temperature, the clock module of RTC can vary with temperature timing error, therefore, RTC clock module commonly used has all added temperature compensation function, timing error can be controlled at ± 5ppm(1,000,000/) in scope, this accuracy of timekeeping error that can guarantee one day is in 0.5 second.At present, the compensation method of RTC timing module is the timing error that adopts multi-point temp (more than 5 or 5) test RTC clock module, then according to the temperature variant conic section of test value match RTC timing module, again by calculating, obtain the offset of each temperature spot, finally offset is deposited in look-up table, according to specified value in table, the RTC timing module is compensated during variations in temperature,, because this method needs multi-point sampler, therefore increased testing cost.
The utility model content
The purpose of this utility model, be to provide a kind of novel real-time clock compensation arrangement, it can pass through 3 temperature tests, the temperature variant conic section of match timing module, and can utilize the means of coarse adjustment and accurate adjustment to adjust the output frequency of RTC clock module, with the drift of compensation RTC clock module with temperature.
Real-time clock compensation arrangement of the present utility model, comprise oscillating crystal, tunable capacitor array, register assembly, data processing unit, decoder, capacitance adjustment unit and frequency modulator, wherein:
This register assembly comprises thermometric temperature register, coefficient of deviation register, summit temperature register and apex offset register;
This data processing unit is connected with this register assembly, is used for accounting temperature and changes conic section and calculated rate deviate;
This decoder is connected with this data processing unit, be used for this exemplary frequency deviation values is decoded, and number of steps is regulated in the output coarse adjustment and number of steps is regulated in accurate adjustment;
This capacitance adjustment unit is connected with this tunable capacitor array with this decoder respectively, is used for regulating number of steps according to this accurate adjustment, and this tunable capacitor array is regulated;
This tunable capacitor array is connected with this oscillating crystal, is used for the frequency of oscillation of this oscillating crystal output of accurate adjustment;
This frequency modulator is connected with this oscillating crystal with this decoder respectively, and for according to this coarse adjustment, regulating number of steps, the frequency of oscillation that this oscillating crystal is exported adds frequency or subtracts adjusting frequently.
Preferably, described frequency modulator is connected with a frequency divider, and be used for that the frequency after described frequency modulator is regulated is carried out frequency division and process, and the output time signal.
Preferably, described data processing unit is digital signal processor or microprocessor.
Real-time clock compensation arrangement of the present utility model, can compensate real-time clock, thereby improved certainty of measurement, but and compensation range wide, probe temperature point is few, precision is high, has effectively reduced the testing cost of chip.
Description of drawings
Fig. 1 is the temperature variant conic section figure of RTC timing module;
Fig. 2 is the equivalent circuit diagram of oscillating crystal;
Fig. 3 is the circuit structure diagram of clock compensation device of the present utility model;
Fig. 4 utilizes this clock compensation device to carry out the flow chart of clock compensation.
Embodiment
Below in conjunction with the drawings and specific embodiments, structure and the operation principle of real-time clock compensation arrangement of the present utility model is elaborated.
As shown in Figure 1, be the temperature variant conic section figure of RTC timing module, the temperature variant characteristic of RTC timing module is exactly the temperature variant characteristic of crystal.This conic section formula Δ f=β (T-T
0)
2+ S
0(formula 1) represents.Wherein Δ f is the exemplary frequency deviation values of the relative conic section of crystal frequency summit frequency, the ppm of unit; β is coefficient of deviation, representative value-0.04ppm/ ℃
2T
0Be conic section summit temperature, representative value is 25 ℃; S
0Be vertical deviation value on conic section summit, representative value has 0, and-20 ,-50 etc.
Be the equivalent circuit diagram of oscillating crystal 110 as shown in Figure 2, wherein C0 is direct capacitance, representative value 2pF; Rm is resonant resistance; Lm is dynamic inductance, representative value 3900H; Cm is dynamic capacity, representative value 6pF; Cin and Cout are load capacitances, representative value 25pF; CT is the tunable capacitor array, has certain adjustable accuracy (stepping amplitude modulation), 1ppm for example, its can-15ppm～+ the 15ppm scope in the accurate adjustment crystal oscillation frequency.
Based on above characteristics, the utility model provides a kind of new real-time clock compensation arrangement.As shown in Figure 3, be the composition schematic diagram of real-time clock compensation arrangement of the present utility model, this real-time clock compensation arrangement comprises oscillating crystal 110, tunable capacitor array 120, register assembly 130, data processing unit 140, decoder 150, capacitance adjustment unit 160 and frequency modulator 170 by reference to the accompanying drawings.
Particularly, this register assembly 130 comprises thermometric temperature register 131, coefficient of deviation register 132, summit temperature register 133 and apex offset register 134.Thermometric temperature register 131 is used for depositing one or more actual temperatures of surveying, and coefficient of deviation register 132 is used for depositing coefficient of deviation β, and summit temperature register 133 is used for depositing conic section summit temperature T
0, the apex offset register is used for depositing vertical deviation value S on conic section summit
0.When initial, any initial value can be write coefficient of deviation register 132, summit temperature register 133 and apex offset register 134, for example all write 0.
Data processing unit 140 is connected with register assembly 130, is used for accounting temperature and changes conic section and calculated rate deviate.Data processing unit 140 can be according to (for example-35 ℃ of three temperature spots of thermometric temperature register, 25 ℃, 75 ℃) pulse per second (PPS) output timing error (ppm value), namely in the difference of the timing of the output valve of three temperature spot standard thermometers and the actual output of real-time clock, according to above-mentioned formula 1, carry out curve fitting or solve an equation, draw β, T0, three parameters relevant to crystal property of S0, and these three values are deposited in corresponding register.
Further, data processing unit 140 also is used for the calculated rate deviate.Particularly, after going out β, T0, S0 and drawing, can, according to the formula 1 after the temperature value that collects (utilizing the standard thermometer collection) and definite parameter, draw the exemplary frequency deviation values Δ f at this temperature.
Data processing unit 140 can be digital signal processor or microprocessor.Such as dsp chip, RAM microprocessor etc.
Decoder 150 is connected with data processing unit 140, be used for exemplary frequency deviation values is decoded, and number of steps m is regulated in the output coarse adjustment and number of steps n is regulated in accurate adjustment.Because the degree of regulation of capacitance adjustment unit 160 can reach 1ppm, the controllable adjustment scope is-15ppm～+ 15ppm; And the frequency that a regulated value corresponding to clock cycle of frequency modulator plus-minus is 30.5ppm(hypothesis crystal is 32768Hz, and the ppm Timing amount of adding and subtracting a clock cycle is 1/32768, i.e. about 30.5ppm).Therefore, the accurate adjustment stepping amplitude modulation of capacitance adjustment unit 160 can be 1ppm, and the coarse adjustment of frequency modulator 160 adjusting stepping amount can be 30.5ppm.At first, decoder 150, according to exemplary frequency deviation values Δ f and coarse adjustment stepping amplitude modulation, is determined coarse adjustment adjusting number of steps, and then according to surplus and accurate adjustment, regulates the stepping amount, determines accurate adjustment adjusting number of steps.
The scope of coarse adjustment is determined by the bit wide of coarse adjustment value fully.For example, the maximum adjusting range of 4 coarse adjustment number of steps is 2
4* 30.5ppm=488ppm, crystal oscillator commonly used is about-200ppm in the maximum temperature of-45 ℃～85 ℃ temperature ranges value of wafing, so coarse adjustment range can be contained different crystal oscillator types on the market fully.Coordinate again accurate adjustment, timing error can be controlled at ± 1ppm.
Capacitance adjustment unit 160 is connected with tunable capacitor array 120 with decoder 150 respectively, is used for regulating number of steps n according to accurate adjustment, and tunable capacitor array 120 is regulated.As mentioned above, capacitance adjustment unit 160 can be according to the adjusting number of steps n that calculates, and the output regulating command, to carry out the accurate adjustment operation to tunable capacitor array 120.
Tunable capacitor array 120 is connected with oscillating crystal 110, is used for the frequency of oscillation of accurate adjustment oscillating crystal 110 outputs.Usually, the accurate adjustment of tunable capacitor array adjusting amplitude modulation is 1ppm.
Frequency modulator 170 is connected with oscillating crystal 110 with decoder 150 respectively, and for according to coarse adjustment, regulating number of steps m, the frequency of oscillation that oscillating crystal 110 is exported adds frequently or subtracts adjusting frequently, is also that coarse adjustment is regulated.As mentioned above, the coarse adjustment stepping amplitude modulation of frequency modulator 170, i.e. the time that every increase and decrease clock cycle brings changes, and is relevant with the frequency of oscillation of output, and for example, as mentioned above, when the frequency of oscillation of exporting was 32768Hz, coarse adjustment stepping amplitude modulation was 30.5ppm.
In addition, frequency modulator 170 is connected with frequency divider 180, and be used for that the frequency after frequency modulator 170 is regulated is carried out frequency division and process, and the output time signal.
As shown in Figure 4, be to utilize this clock compensation device to carry out the flow chart of clock compensation, this compensation method comprises that step S100 is to step S400.Below each step is specifically described.
Step S100.
In this step, three temperature spots are tested, and carried out conic fitting, draw the conic section parameter, and write in corresponding register, wherein, this conic section parameter comprises coefficient of deviation, summit Temperature Quantity and apex offset amount.
For example, can be initially at β, T
0, S
0Insert " 0 " in three registers, then, three temperature spots are tested, draw the pulse per second (PPS) output timing error (ppm) of real-time clock output under three temperature spots, and utilize formula 1 to carry out conic fitting, draw conic section parameter beta, T
0, S
0, write in corresponding register.
Step S200.
In this step, Current Temperatures is gathered, draw actual temperature value, and, according to this conic section parameter, calculate the exemplary frequency deviation values under this actual temperature.
Step S300.
In this step,, according to predetermined coarse adjustment stepping amplitude modulation and accurate adjustment stepping amplitude modulation, calculate coarse adjustment and regulate number of steps and accurate adjustment adjusting number of steps.
After obtaining the said frequencies deviate, the time difference (ppm) that can convert to according to this exemplary frequency deviation values, and according to coarse adjustment stepping amplitude modulation (for example 30.5ppm) and accurate adjustment stepping amplitude modulation (for example 1ppm), the processing of decoding, calculate coarse adjustment and regulate number of steps m and accurate adjustment adjusting number of steps n.
Step S400.
In this step, according to accurate adjustment, regulate number of steps, the tunable capacitor array 120 that oscillating crystal 110 mates is regulated, and according to coarse adjustment, regulate number of steps, the frequency of oscillation of these oscillating crystal 110 outputs is regulated, and the frequency signal of output through regulating.
With reference to Fig. 3, in one embodiment, accurate adjustment Adjust and use capacitance adjustment unit 160 carries out, and so that tunable capacitor array 120 is regulated number of steps according to the accurate adjustment of 1ppm, carries out accurate adjustment; Coarse adjustment Adjust and use frequency modulator 170 carries out, and namely the concussion frequency of the output of oscillating crystal 110 is added frequently (namely increasing one or more clock cycle) or subtracts (namely reducing one or more clock cycle) frequently and process.
, by above step S100-S400, can obtain through overregulating the frequency signal of correction.
Next, in step S500, utilize 180 pairs of frequency signals through regulating of frequency divider to carry out frequency division and process, and the output time signal.By above accurate adjustment and coarse adjustment, can make the error of time signal be controlled at ± scope of 1ppm in.
In sum, real-time clock compensation arrangement of the present utility model, can compensate real-time clock, thereby improved certainty of measurement, but and compensation range wide, probe temperature point is few, precision is high, has effectively reduced the testing cost of chip.
Claims (3)
1. a real-time clock compensation arrangement, is characterized in that, this device comprises oscillating crystal, tunable capacitor array, register assembly, data processing unit, decoder, capacitance adjustment unit and frequency modulator, wherein:
This register assembly comprises thermometric temperature register, coefficient of deviation register, summit temperature register and apex offset register;
This data processing unit is connected with this register assembly, is used for accounting temperature and changes conic section and calculated rate deviate;
This decoder is connected with this data processing unit, be used for this exemplary frequency deviation values is decoded, and number of steps is regulated in the output coarse adjustment and number of steps is regulated in accurate adjustment;
This capacitance adjustment unit is connected with this tunable capacitor array with this decoder respectively, is used for regulating number of steps according to this accurate adjustment, and this tunable capacitor array is regulated;
This tunable capacitor array is connected with this oscillating crystal, is used for the frequency of oscillation of this oscillating crystal output of accurate adjustment;
This frequency modulator is connected with this oscillating crystal with this decoder respectively, and for according to this coarse adjustment, regulating number of steps, the frequency of oscillation that this oscillating crystal is exported adds frequency or subtracts adjusting frequently.
2. real-time clock compensation arrangement according to claim 1, is characterized in that, described frequency modulator is connected with a frequency divider, be used for that the frequency after described frequency modulator is regulated is carried out frequency division and process, and the output time signal.
3. real-time clock compensation arrangement according to claim 1, is characterized in that, described data processing unit is digital signal processor or microprocessor.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203083736U CN203289406U (en) | 2013-05-30 | 2013-05-30 | Real-time clock compensation apparatus |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203083736U CN203289406U (en) | 2013-05-30 | 2013-05-30 | Real-time clock compensation apparatus |
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| CN203289406U true CN203289406U (en) | 2013-11-13 |
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| CN2013203083736U Expired - Lifetime CN203289406U (en) | 2013-05-30 | 2013-05-30 | Real-time clock compensation apparatus |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105759089A (en) * | 2014-10-27 | 2016-07-13 | 马克西姆综合产品公司 | Temperature compensated real-time clock |
-
2013
- 2013-05-30 CN CN2013203083736U patent/CN203289406U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105759089A (en) * | 2014-10-27 | 2016-07-13 | 马克西姆综合产品公司 | Temperature compensated real-time clock |
| CN105759089B (en) * | 2014-10-27 | 2020-03-03 | 马克西姆综合产品公司 | Temperature compensated real time clock |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131113 |