Dilancogo sariyakolow ani sugandili jateminɛw ka ɲɛsin Fractions Frequencies ma Kristali Oscillateurs kɔnɔ
Hardware clock systems dilanni na, injiniyɛriw ka teli ka ɲɔgɔn sɔrɔ ni kristalɛ oscillateur frequences (kristali-yɛrɛyɛrɛli) ye minnu bɛ i n’a fɔ "irregular" (kɔrɔlen", i n’a fɔ 11,0592 MHz, 3,579545 MHz, ani 19.6608 MHz. Nin fɔkan minnu bɛ ni dakun tannanw ye, olu tɛ sugandi u yɛrɛ sago la, nka u ye dilancogo jateminɛw nɔ ye min tɛ se ka bali, minnu sinsinnen bɛ kumaɲɔgɔnya sariyaw kan, frequency-division constraints, ani system-level reverse requirements. K’a daminɛ sariyakolo jɔnjɔnw na, nin barokun in bɛ hakilinaw sɛgɛsɛgɛ minnu bɛ fractions frequences (fɔkanw) bɔli kɔfɛ, ka sɛgɛsɛgɛli kɛcogo ɲumanw di yɔrɔw sugandili kama.
- Core Design Logic of Fractional Frequency Points (Fɛrɛnkan-yɔrɔ-ko-yɔrɔ-ko-yɔrɔ-ko).
I n’a fɔ sistɛmu wagati sɔrɔyɔrɔ, kristalɛ oscillateur ka frequency sugandili bɛ kɛ tuma bɛɛ walasa ka waati tigitigi wajibiyalenw dafa nizɛri sɛrɛkiliw ye minnu bɛ duguma (i n’a fɔ PLLw, dividers ani serial communication). Fractional frequency points bɔli bɛ bɔ fɔlɔ nin dilancogo gɛlɛya suguya naani ninnu na:
1.Ka ladamu UART Jateden dafalenw tilali la walasa ka fili-Free Serial Baud Rates Lajɛ
Baud hakɛ seriyali bɛ bɔ sistɛmu wagati la ka tɛmɛ jateden dafalen tilali fɛ, ka kɛɲɛ ni nin formula in ye: Baud hakɛ=Waati frequency / Division factor
Walasa ka baud hakɛ dantigɛlenw sɔrɔ ka ɲɛ (i n’a fɔ 9600, 19200, walima 115200 bps), wagati fɔcogo ka kan ka tila tilayɔrɔ fɛ ni tolen tɛ. Ni an ye 1,8432 MHz ta misali la, siɲɛ 16 oversampling tilali kɔfɛ:
1,8432 MHz ÷ 16=115.2 kHz, o bɛ bɛn 115200 bps ma.
O cogo kelen na, 11,0592 MHz ni 19.6608 MHz ye siɲɛ 6 ye ani 10,666... siɲɛ 1,8432 MHz, u kelen-kelen bɛɛ (tiɲɛ na, 11.0592=1.8432 × 6, 19.6608=1.8432 × 10,666... bɛ PLL de wajibiya), nka a ka ca ni u ye k’u kɛ waatibolodacogo ye MCUw la i n’a fɔ 51 micro-kontrɔla, min b’a to UART kɔnɔna tilayɔrɔ bɛ se ka baud hakɛ jɔnjɔnw bɛɛ labɔ tilali fɛ. Ni jateden dafalen frequency 20 MHz sugandira, a tɛ se ka tila cogo kelen na ni 115.200 ye, o bɛ na ni fili caman ye ani ka kɛ sababu ye ka frame filiw walima pakew bɔnɛ.
2.Dɛmɛ min bɛ kɛ ka ɲɛsin binary frequency-division architecture ma, o bɛ waati jiri dilanni nɔgɔya
Fɔkan minnu bɛ fɔ i n’a fɔ 20,48 MHz, 10,24 MHz, ani 5,12 MHz, olu bɛɛ bɛ se ka fɔ ni 20 × 10 kHz ye (misali la, 20,48 MHz=2048 × 10 kHz). O fɔkanw kaskad kɔ fɛ ni fɔkan fila tilali ye, sub-waati yɔrɔw i n’a fɔ 10,24 MHz, 5,12 MHz, 2,56 MHz, 1,28 MHz, ani o ɲɔgɔnnaw bɛ Se ka Sɔrɔ. O fɛɛrɛ in bɛnnen don kosɛbɛ{17}}ka ɲɛsin fɔkan tilali waleyali ma ni jatebɔlan fila walima sɛgɛsɛgɛlikɛlanw ye, o bɛ na ni sɛrɛkili sigicogo nɔgɔman ye ni fasa jɛɲɔgɔnyaw ɲɛfɔlen don kosɛbɛ{18}} ani waati danfara bɛnkanw fɔlikan-waati suguya caman ni ɲɔgɔn cɛ. O fɔkanw bɛ kɛ ka caya i n’a fɔ basigi fɔkanw izini DSPw, PLCw ani servo drivew kɔnɔ.
3.Synthesized via PLL walasa ka kumaɲɔgɔnya teliya-teliya ni lamɛnt/wideyow tacogo sariyaw dafa
Bi SoCw, optiki moduluw, ani wideyow labɛnbagaw bɛ PLLw don u kɔnɔ, minnu bɛ baara kɛ ni jateden dafalenw fɔcogo jɔnjɔnw ye (i n’a fɔ 25 MHz walima 24 MHz) i n’a fɔ kunnafoni, o kɔfɛ, u bɛ jateden dafalenw tilacogo kɛrɛnkɛrɛnnenw lawuli minnu tɛ -jateden dafalenw tilali walima u caya fɛ, walima jateden dafalenw tilali fɛ. Misali minnu bɛ kɛ cogoya la, olu ye:
74,25 MHz : Wideyo misali wagati min ɲɛfɔlen don kosɛbɛ-, n’o ɲɛfɔlen don SMPTE sariya fɛ, min bɛ kɛ cogoyaw la i n’a fɔ 1080i ani 720p;
33.1776 MHz: A ka ca a la a bɛ sɔrɔ odio codecs ani broadband RF front-ends kɔnɔ; ni a bɛ baara kɛ ni PLL ye, a bɛ se ka 44,1 kHz walima 48 kHz lamɛntaw tacogo denbayaw lawuli tigitigi;
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A ka kan ka Kɔlɔsi ko fractional frequency division bɛ deterministic jitter ni spurious signals (fɔkan nkalonmaw) Dòn. Baarakɛminɛn minnu bɛ fasa mankan dɔn, fɔlɔ ka kan ka kɛ laɲini fɔkanw ye minnu bɛ se ka sɔrɔ k’a ɲɛsin jateden dafalen mankan tilali ma, walima ka PLLw kɛ minnu mankan ka dɔgɔ-, ni loop bandwidthw labɛnna ka ɲɛ.
4.Tariki Industriw ka sariyaw labatoli ani EMC ka jateminɛw
Tariku protocoles: USB 2.0 bɛ 48 MHz teliya waati dɔ jira; Etɛrinɛti MACw bɛ baara kɛ ni 25 MHz walima 125 MHz ye; ani waati lakikaw-waatiw (RTC) bɛ baara kɛ ni 32,768 kHz (215 Hz) ye. O fɔcogo ninnu tun sigilen don tuma min na sariyaw sigira sen kan, wa kabini o waati, u kɛra izini cakɛda bɛɛ kɔnɔ, ka kɛ sariyaw ye tiɲɛ na.
Electromagnetic Compatibility (EMC): Jateden dafalenw ka harmonikiw sanfɛtaw bɛ se ka ɲɔgɔn sɔrɔ ni kuran dilancogo, RF, walima kumaɲɔgɔnya siraw ye minnu tɛ fili, o bɛ dankari don. Oscillateur frequency sugandili ni fractional component ye, o bɛ se ka harmonic energy jɛnsɛn walima k’a wuli, o la, EMI faratiw bɛ dɔgɔya ani ka filɛri ni shielding musakaw dɔgɔya.
- Fɛn wɛrɛ minnu bɛ Kɛ ni Kristali Oscillateur Sugandili ye
Ka fara frequency value kan, nin ɛntɛrinɛti ko ninnu nafa ka bon cogo kelen na sugandili la:
Fasa Mankan ni Jitter
Hali ni PLLw bɛ se ka frequency suguya bɛɛ lajɛlen kɛ, fractional frequency division bɛ dɔgɔya kosɛbɛ near-end phase mankan ni random jitter. Baarakɛminɛnw kama i n’a fɔ optiki modulu minnu teliya ka bon, milimɛtɛrɛ-rada wave, walima 5G fronthaul, a ka ɲi ka kristalɛ oscillateurs sugandi k’u ɲɛsin u yɛrɛ ma ni frequences natives ye minnu bɛ fasa mankan ɲɛfɔliw dafa walasa ka i yɛrɛ tanga signal integrité margins dafabaliya ma kɔfɛ.
Waati min bɛ ɲɛminɛ ani musaka
Frequences non-standard walima custom, a ka c’a la, olu bɛ waati jan de wajibiya ani u bɛ musaka caman kɛ ɛntɛrinɛti kan. Baarakɛcogo dantigɛli minnu bɛ sɔn, fɔlɔ ka kan ka di izini-fɛrɛnkanw ma minnu bɛ kɛ cogoya la (i n’a fɔ jateden dafalenw fɔkanw minnu bɛ kɛ tuma bɛɛ i n’a fɔ 25 MHz, 27 MHz, 40 MHz, ani 50 MHz, ani sɛrɛkiliw tilayɔrɔba minnu kofɔlen don nin barokun in kɔnɔ) walasa ka R&D sɛrɛkili surunya ani ka BOM musakaw kɔlɔsi.
Bɛnkan ni Sokɔnɔna fɛnw nɔnabila ye
Sisan, sokɔnɔna kuran kristali oscillateur dilannikɛlaw bɛ jateden dafalenw ni jateden dafalenw ka fɔkanw fanba datugu minnu bɛ kɛ ka caya. Ni aw bɛ minɛn dɔ sugandi, aw bɛ aw sinsin fɛnw sɔrɔli sabatili kan, funteni cogoyaw (i n’a fɔ ±10 ppm ani ±20 ppm), ani doni hakɛ dantigɛliw walasa ka bɛn ni jatigila kunnafonidila puwɛnti ka waati doncogo wajibiyalenw ye.
- Sugandili kɛcogo ɲumanw
Fɔlɔ,sitɛmu waati dantigɛliw latigɛ: Waati hakɛ tigitigi minnu wajibiyalen don periferiw bɛɛ fɛ (UART, I2S, SPI, Ethernet, USB, Video) ani u filiyɔrɔ minnu bɛ se ka kɛ, olu sɛbɛn.
Aw bɛ kristalɛ oscillateur fondamental frequency sɔrɔ kɔfɛ:Ni mikrokontrɔla bɛ ni PLL ye min jɔlen don-, i ka reference cristal oscillateur sugandi min bɛ se ka laɲini frequences (fɔkanw) labɔ ni jateden dafalenw ye walima ni jateden dafalenw ye walima ni tila-tilacogo dɔgɔmanw ye. Aw bɛ fɔlɔ di frequences ma minnu tilali hakɛ ka dɔgɔ ni 100 ye ani denominator min fanga ye 2 ye.
Aw ye tilali fili sɛgɛsɛgɛ: Jatebɔ kɛ ni tilali fili ka dɔgɔ ni baud hakɛ/sampling rate deviation maksimali ye min bɛ se ka kɛ periferiw fɛ (a ka c’a la < ±2%).
EMI farati jateminɛ:Aw bɛ spektral analyse kɛ harmoniques high-frequences kan; ni a mago bɛ a la, frequency point dɔ sugandi min bɛ bɔ integer-order harmonics la.
Aw ye jateminɛ kɛ sɔrɔli ni musakaw la: Ni aw bɛ baarakɛcogo wajibiyalenw dafa, aw bɛ modɛli dɔ sugandi min bɛ sugu sɔrɔ kosɛbɛ ani pake suguya (misali la, HC-49S, SMD 3,2 × 2,5 mm) min bɛ se ka baara kɛcogo wajibiyalenw dafa.