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5

As @Majenko commented, the A0 input has a fixed voltage divider (see NodeMCU Schematics) that connects the A0 input to a 220kOhm resistor, then to the ADC pin of the ESP8266, then to ground via a 100kOhm resistor. This effectively fixes the resistor values that can be used to scale the input of the NodeMCU. For a 0-5.0V input range (with sufficiently low ...


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Can you make Arduino Uno send information through a WiFi module to a server? Yes, I can. The simplest way is through an HTTP "GET" request. Every time you request a web page (and there are plenty of examples of that) you are sending data to the server to tell it both what web page to get (/foo/bar.php) and what data to submit to that web page (?baz=4). It'...


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Most PIR sensors provide a simple relay output. That means they are nothing more than a switch as far as the Arduino is concerned. You can connect hundreds of switches to an Arduino. With judicious use of diodes and a matrix arrangement you can hundreds with not many IO pins. For example an 8x8 matrix of switches gives you 64 PIR sensors with just 16 IO ...


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The low end of the values is limited by how much current your sensor can provide. If you use 1Ω and 2Ω resistors in series then your sensor will need to provide 1.67A to create 5V across the divider. I doubt that your sensor can do that. For most sensors, you would want to use resistors in the kilohm or tens of kilohm range. The high end is ...


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Since all of these cheap fingerprint readers are similar you can find a compatible datasheet and just find the commands and descriptions there. However, I couldn't find a datasheet that would include a good description of the protocol. So the other option is to look at the protocot through the software SFGDemo which is apparently capable of getting an image ...


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DHT11 sensor uses a "single-Wire" protocol with open drain IOs. so it's fine for cable to be long. use a lower value Pull-up resistor for Data line of DHT11. the datasheet says a 5K pull-up resistor is enough for up to 20m wire length. the process of reading a sensor can't be paralleled. you have to read them one at a time, store them on a local variable and ...


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The problem was on the soldering part. SDA & 3.3V pin on sensor were slightly in contact. I modified it and started working fine.


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