Customer:
I bought the board and have 2 questions about it:
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The specification says the operating voltage is 5V, but the description says it’s designed for 3.3V with a 5V regulator on board. I don’t understand what that means. What voltage do I use to power it? What voltage do I get on the GPIO outputs? Is there an output on the board that provides 5V?
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The guidance says to monitor current through the board. What is the current limit?
I was planning to control 14-15 relays with it. They would be in the open position for a couple of minutes before being switched off.
Original message (Croatian)
kupio sam pločicu i sada kužim da imam 2 pitanja vezana uz istu:
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U specifikaciji piše da je radni napon 5V, a opisu da je dizajn za 3.3V s 5V regulatorom na sebi. Ne znam što to znači. Kojim naponom ga napajam? Koji napon imam na izlazu iz GPIO? Ima li neki izlaz na pločici koji daje 5V van?
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U savjetima piše da se prati struja kroz pločicu. Koje je ograničenje na struju?
Ja sam planirao pokretati 14-15 releja (SKU: 101287) s njom. Isti bi bili u otvorenom položaju nekih par minuta prije iskapčanja.
Originally submitted via email support on 1 December 2023. Migrated to the forum for community visibility.
Soldered Support:
The board is powered with 5 V (you can power it via the VCC pin by bringing in 5 V or use USB for power). If you power the board from USB, you can use the VCC pin as a 5 V output (it will be slightly lower around 4.8 V due to the fuse on the board and protection diode). The board has a 3.3 V regulator for the easyC connector, but the microcontroller is powered with 5 V and the output signal on its pins will be 0 V to 5 V.
The current limit is 500 mA because that’s the USB 2.0 standard and we put a 500 mA fuse on the board (this is for the entire board). For each controller pin the maximum current is 20 mA. To connect relays you will need a driver (a circuit with a transistor that switches the relay) so that circuit will be powered with 5 V, and the controller pin will then control the transistor.
Since you plan to use 15 relays you will need external power (unless you never plan to turn on all relays at the same time). Each relay requires about 80 mA to activate so for 15 relays you need 1200 mA which is too much for the Dasduino board.
Original message (Croatian)
Pločica se napaja s 5 V (možete napajati na VCC pin da dovedete 5 V ili koristiti USB za napajanje). Ako pločicu napajate s USB-a , onda VCC pin možete koristiti kao izlaz za 5 V napajanje (bit će nešto manji napon oko 4.8 V zbog osigurača na pločici i zaštitne diode). Pločica na sebi ima 3.3 V regulator za easyC konektor, ali se mikrokontroler napaja s 5 V te će izlazni signal na njegovim pinovima biti od 0 V do 5 V.
Ograničenje struje je 500 mA jer je to standard za USB 2.0 te smo stavili osigurač od 500 mA (to je za cijelu pločicu). Za svaki pin kontrolera maksimalna struja je 20 mA. Za spajanje releja će vam svakako trebati neki drajver (sklop s tranzistorom koji pali relej) tako da će se taj sklop napajati s 5 V, a pin kontrolera će onda kontrolirati tranzistor. Preporučio bi da koristite naš breakout Jednokanalni relej Pločica za upravljanje visokim naponom – Soldered Electronics za jednostavniji rad.
Kako planirate koristiti 15 releja trebat će te vanjsko napajanje (osim ako nikada ne planirati paliti sve releje u isto vrijeme). Svaki relej treba oko 80 mA za aktiviranje tako da vam za 15 releja treba struja od 1200 mA što je previše za Dasduino pločicu.
Ako nešto nije jasno ili treba detaljnije objasniti slobodno se povratno javite.
Customer:
I understand now. I’m thinking about powering the relay with an optocoupler. If I understood correctly, the optocoupler you have in your catalog can be driven with 5V and I can limit the input current through it to 20mA with a series resistor. But on the output I can’t have more than 50mA while I need 80mA for the relay?
Original message (Croatian)
zahvaljujem na brzom i jasnom odgovoru. Sve sam shvatio. Samo sada razmišljam o napajanju releja optocouplerom. Ako sam dobro shvatio… Samo na izlazu ne smijem imati više od 50mA dok mi za relej treba 80mA? LP, I.[name removed]
Soldered Support:
The optocoupler is essentially an LED and phototransistor in the same package. To control it you need to limit the current to 20mA (accounting for the LED forward voltage of 1.5V). Yes, the current is specified as a maximum of 50mA or 100mA if the pulse is less than 1ms. You would need to use a different optocoupler that has higher transistor current capability.
Original message (Croatian)
Tako je optocoupler je zapravo LEDica i fototranzistor u istom kućištu. Za kontrolu trebate ograničiti struju na 20mA (računajući da je napon LEDice 1.5V).
Da za struju je navedeno da je maksimalna struja 50mA ili 100mA ako je impuls manji od 1ms. Trebalo bi koristiti neki drugi optocoupler koji ima veći struju tranzistora.