33 votes

What are the 5V and VIN pins for?

No. You can draw power from the 5v and VIN pins on the arduino. VIN is the completely unaltered input power before the regulator (it will be useless if regulated 5v is supplied directly). Outputting ...
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  • 4,309
32 votes

How to identify Arduino Mini Pro 5v vs 3.3v

Consideration (go down for the actual solution) If you have a lot of different China-Arduino-clones, the easiest way will be to just test it. The cloned Arduinos use a lot of different voltage ...
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  • 421
22 votes
Accepted

How to identify Arduino Mini Pro 5v vs 3.3v

The regulator should be marked K850(5.0V) or K833(3.3V). A 5 volt part has a 16MHz resonator may be marked with "A1" or "A'N" A 3.3 volt part has a 8MHz resonator may be marked with "80'0" As others ...
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  • 456
15 votes
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Does ADC conversion to a voltage rely on the actual value of the +5 V pin?

The ADC inside the Arduino does not measure voltage, but rather a voltage ratio. Namely the ratio from the voltage at the analog input to the voltage at the Vref pin. In the default configuration, ...
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13 votes
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How to output a true analog voltage at output pin

You basically have three options: Switch to an Arduino Due which has a built-in DAC which outputs a real voltage. Add an external DAC chip (such as the MCP4821/2) to create the voltage for you Use a ...
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  • 103k
11 votes
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Two batteries sharing ground?

Not only can you share the grounds - sharing the grounds is required for there to be any form of meaningful circuit for signals to get around the place. To copy-and-paste a blog post I wrote some time ...
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  • 103k
10 votes

Convert Arduino Pro Mini 5v to use 3.3v

I have good news, and I have bad news. The good news is that only two changes to the board are required to change it from a 5V board to a 3.3V (or any voltage within spec) board. The bad news is ...
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9 votes
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Power supply voltage confusion

The board has a voltage regulator which converts 9-12V to the 5V that the chip uses. Why does it need 9V if the board works at 5V? Well, it doesn't need 9 exactly, but it needs something greater than ...
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  • 7,283
9 votes

What is the Vin Pin for?

The Vin pin serves the same purpose as the barrel jack. The only difference is (usually) that it doesn't go through the schottky protection diode that causes a small voltage drop. Normally its ...
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  • 103k
9 votes
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Powering Arduino Uno from 5V pin, what exactly is the voltage range/tolerance?

Unfortunately there is no one "clear cut" answer for all you ask. There are some hard limits, though, which you can get from the main chip's datasheet: Operating Voltage: 1.8 - 5.5V But that's ...
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  • 103k
9 votes

Does ADC conversion to a voltage rely on the actual value of the +5 V pin?

A USB-powered Arduino Nano will have an ADC voltage reference which can't be relied on, due to the +/- 5% tolerance of the incoming USB voltage. On top of that, the Nano has an MBR0520 Schottky diode (...
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  • 2,102
8 votes
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How to program ATTiny85 running 3.3V

Since the ATTiny can easily run at 5V I don't see any problem with programming it at 5V levels and then run it at 3.3V. Is that correct? Yes. But if there are any components on the board that can't ...
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7 votes

Power supply voltage confusion

And the third part of your question: It is possible to bypass the voltage regulator and feed REGULATED 5 volts directly to the 5V pin. That's how the Arduino is powered using USB. The USB power is ...
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  • 5,509
7 votes

How to identify Arduino Mini Pro 5v vs 3.3v

The safe way (i tested it). First connect to 3.3V USB-TTL output first (also 5V Mini can work with 3.3V). Now prepare this sketch: void setup() { pinMode(13, OUTPUT); } void loop() { ...
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  • 71
7 votes
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When it says the Uno has logic level at 5 V is that also true of a bareduino/breadboard Arduino?

The logic level is the same as the voltage you supply the chip. You can think of the IO pins as tiny switches that either connect the output pin to the supply voltage or to ground (when in output ...
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  • 103k
7 votes
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Precision voltmeter using Arduino

A divider is used to (as the name suggests) reduce a higher voltage to a lower voltage. Using a divider on a small voltage will only make it smaller and harder to measure. To get the most out of ...
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  • 103k
7 votes
Accepted

Do I use 3,3V or 5V, when device supports both?

Using the MAX3232 data sheet , which is what the TTL Converter has on it's board : The main difference between using 3.3v or 5v is on the receiver data line "R" (or Rout as it is called on the ...
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  • 600
7 votes

How to output a true analog voltage at output pin

At 5V, a 1 ohm resistor will try to sink 1A and far exceed the 40mA specs. Please use at least a 5/0.040=125 ohm resistor to protect your pin. And if you put the a capacitor between your resistor ...
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  • 2,322
7 votes
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Getting 3.3v on 5v pin in Arduino Uno

and an external 5V DC power supply OK, assuming you are putting 5V into the barrel jack this is exactly what you expect to happen. From the Arduino Uno specifications you are supposed to supply a ...
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  • 35.3k
7 votes
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How can I create a battery level circuit

Firstly, if I understand your schematic right, you're not "dividing" anything there. If the ringed red symbol is where you are connecting the ADC then either you will see near 4V on there (if it's ...
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  • 103k
6 votes

Multiple Buttons on Single Analog Pin and Trigger Pin Arduino Uno

Use the analog comparator in the ATmega328P to trigger an interrupt once the input voltage rises enough to indicate a button press. Connect the analog network to both the analog input and D6. If ...
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6 votes
Accepted

Set Arduino digitalRead reference voltage

You could try not digitalRead, but analogReadVoltage. Analog Read Voltage From Arduino examples: /* ReadAnalogVoltage Reads an analog input on pin 0, converts it to voltage, and prints the ...
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  • 538
6 votes

What maximum length of wire can I use to connect a push button to an Arduino?

Q: how far can you go with 5v and still get signal back? That depends on two main factors: The gauge of the wire The noise in the environment Assuming a low-noise (where noise is negligible) ...
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  • 103k
6 votes
Accepted

How to power my Arduino mini using wall socket?

I have connected the Relay and IR receiver directly to the Arduino mini. Pin 10-14 are used for the relays Ins and PWD 3 for IR output. I hope you don't mean that you have connected the coils of ...
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  • 2,102
6 votes

Logic level converter not working?

Based on your schematic, you need to provide a 3.3v power source to the 3.3v side of the logic level converter. You can use the 3.3v pin on the Arduino. Also, it's really hard to evaluate your ...
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  • 1,091
6 votes

How to measure the supply voltage of Arduino without using an analog pin

Yes, you can do it. You can measure the voltage of the internal (approximately) 1.1V reference voltage using the ADC and use the results of that to calculate what the reference voltage you used (VCC) ...
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  • 103k
5 votes
Accepted

Operating / pin voltages ATTiny chips

Yes. As given in the datasheets, normal ATtinyX4/X5 chips can run with a supply between 2.7 and 5.5V inclusive, whereas the low-power versions can run between 1.8V and 5.5V. Mind the speed ...
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5 votes

Can I change VCC pin to 3.3V on a 5V Arduino Pro Micro?

No. If you change the voltage to 3,3 Volt you also have to change the crystal to 8MHz and reprogram the ATmega32u4 to meet the new frequency.
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  • 1,306
5 votes

What are the 5V and VIN pins for?

5V pin can be used to power up shields like Bluetooth, RFID, ultrasonic sensors etc.. vin pin is used to power up the Arduino. For example, when using shields such as L298 motor shield which is ...
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5 votes

What are the 5V and VIN pins for?

They can also be used to draw power from the barrel jack (Vin) or from USB or the on-board regulator (5V). The schematic of the board shows all exact power paths.
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