Iindaba

I-Pulse-width modulation (PWM) ligama eliqhelekileyo lohlobo lwesignali yedijithali. Ii-PWM zisetyenziswa kwiinkqubo ezahlukeneyo, kubandakanywa neesekethe zokulawula eziyinkimbinkimbi. Indlela eqhelekileyo esizisebenzisa ngayo e-SparkFun kukufiphalisa i-RGB LED okanye ukulawula icala le-servo. Sinokufikelela uluhlu lweziphumo kuzo zombini ezi zicelo kuba i-PWM isivumela ukuba sitshintshe inani lexesha uphawu luphezulu ngendlela ye-analog. Ngelixa umqondiso unokuba phezulu kuphela (ngokuqhelekileyo i-5V) okanye ephantsi (umhlaba) nangaliphi na ixesha, sinokutshintsha umlinganiselo wexesha umqondiso uphezulu xa kuthelekiswa nezantsi kwixesha lexesha elingaguqukiyo.

Isekile yomsebenzi

Xa umqondiso uphezulu, siwubiza "ngexesha." Ukuchaza inani "ngexesha," sisebenzisa ingqikelelo yomjikelo womsebenzi. Umjikelo womsebenzi ulinganiswa ngeepesenti. Ipesenteji yomjikelo womsebenzi ichaza ngokuthe ngqo ipesenti yexesha umqondiso wedijithali ungaphakathi kwithuba elithile okanye ixesha. Ixesha lijikelelo lokuphindaphinda kohlobo lwamaza. Ukuba isignali yedijithali ikwisiqingatha sexesha kwaye iphuma kwesinye isiqingatha, sithi isignali yedijithali inomjikelo we-50% womsebenzi, ofana ne-square wave efanelekileyo. Ukuba ipesenti iphezulu kune-50%, umqondiso wedijithali uchitha ixesha elide kwindawo ephakamileyo kunesimo esiphantsi, kwaye ngokuphambene noko ukuba umjikelezo womsebenzi ungaphantsi kwama-50%. Lo mzobo ulandelayo ubonisa ezi meko zintathu:

Umjikelo we-100% womsebenzi ufana nokubeka i-voltage kwi-5 volts (phezulu). Umjikelo we-0% uyafana nokudibanisa umqondiso emhlabeni.

umzekelo

Unokulawula ukuqaqamba kwe-LED ngokuhlengahlengisa umjikelo womsebenzi.

Nge-RGB (ebomvu, eluhlaza, nebhlowu) ii-LEDs, unokulawula ubungakanani bombala ngamnye kwemithathu exutywe ngokuyifiphalisa ngezixa ezahlukeneyo.

Ukuba zonke ezithathu zivulwe ngamanani alinganayo, umphumo uya kuba yimibala eyahlukeneyo yokukhanya okumhlophe. Ukuxuba okufanayo kweblue kunye nohlaza kuya kudala umbala ohlaza okwesibhakabhaka. Ngomzekelo ontsokothileyo ngakumbi, zama ukuvula umbala obomvu ngokupheleleyo, luhlaza ngokupheleleyo kwi-50% yomjikelo womsebenzi, kunye noluhlaza okwesibhakabhaka ngokupheleleyo ukwenza umbala o-orenji.

Xa ulawula ii-LED, i-frequency ye-square wave kufuneka ibe phezulu ngokwaneleyo ukufezekisa i-dimming effect efanelekileyo. I-20% yomjikelo wamaza kwi-1 Hz iya kubonisa ngokucacileyo ukuba ivula kwaye icime iliso lakho, ngelixa i-100% yomjikelo we-20 Hz okanye ngaphezulu iya kubonakala imfiliba kunaxa ivuliwe ngokupheleleyo. Ngokusisiseko, ukuba injongo yakho kukufumana isiphumo sokuncipha kwee-LEDs, ixesha alinakuba likhulu kakhulu. Unokuphinda usebenzise i-pulse-width modulation ukulawula i-engile ye-servo motor eqhagamshelwe kwisixhobo somatshini njengengalo yerobhothi. I-servo ine-shaft ejika kwindawo ethile ngokusekelwe kumgca wayo wokulawula. Iinjini zethu ze-servo zinoluhlu olumalunga ne-180 degrees.

I-frequency / ixesha likhethekileyo ekulawuleni i-servo ethile. I-servo motor eqhelekileyo ilindele ukuhlaziywa rhoqo nge-20 ms, kunye ne-pulse phakathi kwe-1 ms kunye ne-2 ms-ngamanye amazwi, umjikelo womsebenzi phakathi kwe-5% kunye ne-10% kwi-50 Hz waveform. Nge-1.5 ms pulse, i-servo motor iya kuba kwindawo yayo yendalo ye-90-degree. Kwi-pulse ye-1ms, i-servo iya kuba kwii-degrees ze-0, kwaye kwi-2ms pulse, i-servo iya kuba kwii-degrees ze-180. Unokufumana uluhlu olupheleleyo lwesindululo ngokuhlaziya i-servo kumaxabiso phakathi.

I-Pulse-width modulation isetyenziswa kwiinkqubo ezahlukeneyo, ngakumbi ukulawula. Ngoku uyazi ukuba ingasetyenziselwa ukunciphisa ii-LED kunye nokulawula i-engile yee-motor ze-servo, ungaqala ukujonga ezinye iindlela ezinokusetyenziswa. Ukuba uziva ulahlekile, zive ukhululekile ukujonga iKhithi ye-SparkFun Inventor, equka imizekelo esebenzisa i-pulse-width modulation. Ukuba ukulungele ukuqalisa iikhowudi kwangoko kwaye ube neArduino, jonga imizekelo yekhowudi ye-PWM apha.