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33 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 ...
mozzbozz's user avatar
  • 431
15 votes
Accepted

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, ...
Edgar Bonet's user avatar
  • 43.3k
13 votes
Accepted

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 ...
Majenko's user avatar
  • 105k
12 votes
Accepted

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 ...
Majenko's user avatar
  • 105k
9 votes
Accepted

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 ...
Majenko's user avatar
  • 105k
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 (...
Enric Blanco's user avatar
  • 2,114
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 ...
Dave X's user avatar
  • 2,332
7 votes
Accepted

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 ...
Nick Gammon's user avatar
  • 38.3k
7 votes
Accepted

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 ...
Majenko's user avatar
  • 105k
7 votes

Same LED but different brightness on same PIN

All the pins are configured as INPUT by default on startup. So if you leave out the pinMode(7, OUTPUT);, pin 7 will still be configured as input. An Input doesn't provide any current (or only a very ...
chrisl's user avatar
  • 16.3k
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 ...
Enric Blanco's user avatar
  • 2,114
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 ...
Mazaryk's user avatar
  • 1,149
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) ...
Majenko's user avatar
  • 105k
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 ...
nuwan karunarathna's user avatar
5 votes
Accepted

How do I turn off a 12V 3A RGB LED strip?

That's pretty simple: when you turn off all the colours you are actually turning off the entire strip with very minimum leakage current in each of the three FETs.
Roberto Lo Giacco's user avatar
5 votes
Accepted

WS2812 - First are white and then they turn red/yellow/orange near the end

See Powering NeoPixels. Each individual NeoPixel draws up to 60 milliamps at maximum brightness white (red + green + blue). ... To estimate power supply needs, multiply the number of ...
Nick Gammon's user avatar
  • 38.3k
5 votes
Accepted

This logic level converter does not want to work

The TSX0108 doesn't magically provide you with a regulated voltage. You have to provide the voltage, the TSX0108 merely switches it. As you can see from the datasheet, the basic wiring is: In the ...
Majenko's user avatar
  • 105k
5 votes
Accepted

Does the Arduino Yun have to be powered exactly at 5V?

It is fine. That is only 2% too high. The microcontroller is the ATmega32U4 and it can have 5.5V. The wifi module runs at 3.3V, and it has a voltage regulator. Some voltage is also lost in the cable. ...
Jot's user avatar
  • 3,246
5 votes

The need to use logic level converter

Level logic converting for level shifting is different from powering a device. Logic level is the state of a digital input/output. No voltage (or very little of it) is considered LOW. Over the ...
Juraj's user avatar
  • 18k
5 votes
Accepted

Digital I/O threshold voltages for ATmega32u4

LVTTL is Low Voltage Transistor-Transistor Logic. In general, the term "TTL" is used for a digital signal. The "Low Voltage" part is special, the ATmega32U4 switches from low to high (and vice versa) ...
Jot's user avatar
  • 3,246
5 votes
Accepted

Output voltage range between 0-5v

Short answer: No. Arduino Unos and Megas have PWM (Pulse Width Modulation) output, which rapidly turn the output on and off with a varying "duty cycle" (The ratio of on time to off time.) ...
Duncan C's user avatar
  • 5,702
4 votes

Confusion with ATmega328P and 3.3V/8MHz

If you are using an LED to indicate that your sketch is running, then that may be the problem. For example, if you have a fairly average red LED, it might have a forward voltage of 2.0v @ 20ma (...
AMADANON Inc.'s user avatar
4 votes

How to reduce current from a AC TO DC power supply for arduino use

You don't need to reduce the current. 2000MA (2 amps) means the power supply is CAPABLE of supplying this (without overheating). Anything less than this, and your device will work perfectly. Your ...
AMADANON Inc.'s user avatar
4 votes
Accepted

Confusion with ATmega328P and 3.3V/8MHz

It was a brownout fuse problem. Changing boards.txt from: atmega328bb.bootloader.extended_fuses=0x05 to atmega328bb.bootloader.extended_fuses=0x02 solved it for me (*). The chip and red LED now ...
Paul Grime's user avatar
4 votes
Accepted

Reduce 5v Trinket Pro to 3.3v?

The NRF24L01+ has inputs that are 5V tolerant! So you only need to provide 3.3V on the Vcc pin of the module, which you can do by putting a voltage regulator between it, and the 5V of the Trinket. So ...
Gerben's user avatar
  • 11.3k
4 votes
Accepted

Arduino Pro Mini maximal and recommended current per pin

It is the amount of current the pin can source or sink when in OUTPUT mode. That is, the amount of current that can flow from the pin to ground, or can flow from VCC into the pin. You can understand ...
Majenko's user avatar
  • 105k
4 votes

How can I wire a 12V LED switch so that it is powered, but my Arduino only receives a 5V signal?

You need a voltage divider: The formula is: V1 = 12V R2 = 5V max R1 = The rest (V1-R2) And then you have to calculate max current. If you use 1/4watt resistors, you have to convert watt to ...
MatsK's user avatar
  • 1,356
4 votes
Accepted

How to switch a low-voltage (1.5V) toy motor with an arduino?

You would be better off using a MOSFET which, when on, has quite a low resistance. For example the RFP30N06LE datasheet shows a RDS(on) of 0.047 Ω at 30A and 5V. Using Ohm's Law we therefore expect a ...
Nick Gammon's user avatar
  • 38.3k
4 votes
Accepted

How much low analog voltage can Arduino uno read?

The Arduino Uno uses a processor containing a 10 bit ADC. This means the ADC can resolve (if we do not consider noise) 2 to the 10th or 1024 voltage levels between zero and the voltage supplied to ...
st2000's user avatar
  • 7,338

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