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If your chosen power supply is of a good quality and provides proper ground isolation then it shouldn't be a problem to connect the grounds of the two systems together. However, since there are so many bad power supplies available on the internet (and even some "good" power supplies are somewhat iffy when it comes to grounding) it is safest to hedge your ...


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Can I directly connect an ESP GPIO pin to the base of the transistor where the arduino is connected? No. You will effectively be connecting two outputs together, and that is very bad. Instead you will need to add a second transistor in parallel to the first - one controlled by the Arduino and one controlled by the ESP-01. Can I put a relay module ...


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I think what you're looking for is to declare your functions near the top of your file, usually before the first function you write, setup(), in this case. So add this just above your setup() function: // Forward function declarations void displayNumber(void); void checkUp(void); void checkDown(void); void checkStart(void); void countDown(void); C ...


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Here is some code that might help you; leaving out the temperature and humidity stuff: // constants // number or relays const int relays = 4; // pins for the relays const int relayPins[] = {2, 3, 4, 5}; // relay cycle times const unsigned long relayTimes[] = { 5*60*1000, // 5 min 60*60*1000, // 1 Hour 2*60*60*1000, // 2 hours 12*60*60*...


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I had this same issue with an ESP8266 NodeMCU-12E using Cayenne in the past. It would drop connection for no apparent reason, but no matter what, most of the time it'd never reconnect until a reset. Here's what I did: CAYENNE_DISCONNECTED(){ Serial.println(F("Cayenne disconnected, rebooting...")); ESP.restart(); } I've never used Blynk before, but ...


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When you set a pin to HIGH then that pin will provide 5V. When you set a pin to LOW then that pin will be set to 0 volts. Which direction the current flows depends on what is at the other end of the wire. Current always flows from higher voltage to lower voltage. If you set a pin to HIGH and the thing it is connected to is at ground then current will ...


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