Nkhani

Pulse-width modulation (PWM) ndi mawu apamwamba a mtundu wa chizindikiro cha digito. Ma PWM amagwiritsidwa ntchito m'njira zosiyanasiyana, kuphatikiza mabwalo owongolera ovuta. Njira wamba yomwe timawagwiritsira ntchito ku SparkFun ndikuchepetsa RGB LED kapena kuwongolera komwe servo imayendera. Titha kupeza zotsatira zosiyanasiyana muzogwiritsira ntchito zonsezi chifukwa PWM imatilola kuti tisinthe nthawi yomwe chizindikiro chili pamwamba pa njira ya analogi. Ngakhale kuti chizindikirocho chikhoza kukhala chapamwamba (kawirikawiri 5V) kapena chotsika (pansi) nthawi iliyonse, tikhoza kusinthasintha nthawi yomwe chizindikirocho chili chokwera poyerekeza ndi chochepa pa nthawi yokhazikika.

Ntchito yozungulira

Chizindikiro chikakhala chapamwamba, timachitcha "panthawi yake." Kufotokozera kuchuluka kwa "panthawi yake," timagwiritsa ntchito lingaliro la ntchito. Nthawi yantchito imayesedwa ndi magawo. Maperesenti a ntchito amafotokoza mwatsatanetsatane kuchuluka kwa nthawi yomwe chizindikiro cha digito chili mkati mwa nthawi kapena nthawi. Nthawiyi ndi yosiyana ndi ma frequency a waveform. Ngati chizindikiro cha digito chili pa theka la nthawi ndikuchoka theka lina, timati chizindikiro cha digito chili ndi 50% yozungulira, yofanana ndi mafunde abwino. Ngati chiwerengerocho ndi chapamwamba kuposa 50%, chizindikiro cha digito chimathera nthawi yochuluka kumtunda kusiyana ndi malo otsika, ndipo mosiyana ngati ntchitoyo ili pansi pa 50%. Chithunzi chotsatirachi chikuwonetsa zochitika zitatu izi:

Kuzungulira kwa 100% ndikofanana ndikuyika voliyumu ku 5 volts (mkulu). Kuzungulira kwa 0% ndikofanana ndi kulumikiza chizindikiro pansi.

chitsanzo

Mutha kuwongolera kuwala kwa LED posintha kuzungulira kwa ntchito.

Ndi ma RGB (ofiira, obiriwira, ndi abuluu) ma LED, mutha kuwongolera kuchuluka kwa mitundu itatu iliyonse yosakanizidwa poyichepetsa mosiyanasiyana.

Ngati onse atatu ayatsidwa mulingo wofanana, zotsatira zake zimakhala zowala mosiyanasiyana. Kusakaniza komweko kwa buluu ndi zobiriwira kudzapanga mtundu wa bluish-wobiriwira. Pachitsanzo chovuta pang'ono, yesani kuyatsa zofiira, zobiriwira zonse pa 50% ya ntchito, ndi buluu kuti mupange mtundu wa lalanje.

Mukawongolera ma LED, ma frequency a square wave amayenera kukhala okwera mokwanira kuti akwaniritse dimming yoyenera. Mafunde a 20% pa 1 Hz akuwonetsani kuti akuyatsa ndi kuyimitsa diso lanu, pomwe 100% yantchito pa 20 Hz kapena kupitilira apo idzawoneka yocheperako kuposa ikamayaka. Kwenikweni, ngati cholinga chanu ndikukwaniritsa kufooka ndi ma LED, nthawiyo singakhale yayikulu kwambiri. Mutha kugwiritsanso ntchito kusinthasintha kwa pulse-width kuwongolera mbali ya servo motor yolumikizidwa ndi makina amakina ngati mkono wa loboti. Servo ili ndi shaft yomwe imatembenukira kumalo enaake kutengera mzere wake wowongolera. Ma servo motors athu ali ndi mitundu pafupifupi 180 madigiri.

Mafupipafupi / nthawi ndi yachindunji kuwongolera servo inayake. Makina amtundu wa servo amayembekeza kusintha ma 20 ms aliwonse, ndi kugunda pakati pa 1 ms ndi 2 ms-mwanjira ina, kuzungulira kwa ntchito pakati pa 5% ndi 10% pa mawonekedwe a 50 Hz. Ndi kugunda kwa 1.5 ms, injini ya servo idzakhala pamalo ake achilengedwe a 90-degree. Pa kugunda kwa 1ms, servo idzakhala pa madigiri 0, ndipo pa 2ms pulse, servo idzakhala pa madigiri 180. Mutha kupeza zoyenda zonse posintha ma servo kukhala ma values ​​pakati.

Pulse-width modulation imagwiritsidwa ntchito m'njira zosiyanasiyana, makamaka kuwongolera. Tsopano popeza mukudziwa kuti itha kugwiritsidwa ntchito kuchepetsa ma LED ndikuwongolera mbali ya ma servo motors, mutha kuyamba kuwona momwe mungagwiritsire ntchito zina. Ngati mukumva kuti mwatayika, omasuka kuyang'ana SparkFun Inventor's Kit, yomwe ili ndi zitsanzo zogwiritsa ntchito kusinthasintha kwa pulse-width. Ngati mwakonzeka kuyamba kulemba zolemba nthawi yomweyo ndikukhala ndi Arduino, onani zitsanzo za PWM apa.