15 votes

Why connect a diode between the reset pin of Arduino and 555 timer?

It's called a "Wired Or" arrangement. The Arduino's RESET pin has a pullup resistor in it (10KΩ). That keeps the RESET pin normally HIGH. To invoke a reset that pin needs pulling low, and that is ...
Majenko's user avatar
  • 105k
8 votes
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Why would the resistor be after the LED in this project?

It does not matter if a resistor is before or after a component, see the circuits below. The resistor reduces the current, and this is true for the path where the resistor is in (until the ...
Michel Keijzers's user avatar
7 votes
Accepted

Need help figuring out the pinout of a seven segmented display

Without an image of the display, I'll have to guess. With 12 pins in total, what you most likely have is: 8 pins for 7 segments and the decimal point, and 4 COMMON anodes or cathodes, a detail you ...
SoreDakeNoKoto's user avatar
6 votes
Accepted

Why can't most servos rotate more than around 180°

Fundamentally, because the systems they were designed for convert rotary motion to linear, typically with a range substantially less than 180 degrees (probably more like 120 degrees). Next, because ...
Chris Stratton's user avatar
6 votes

Voltage changes but digitalRead always HIGH

The problem is that when the button isn't pressed, the voltage at pin D3 is just floating. Since there is nothing attached, the voltage at the pin can be anything. To prevent this, you use a pull-down ...
Gerben's user avatar
  • 11.3k
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
5 votes
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What is difference between analog and digital input and output, and when should i use anlog or digital (input or output)?

You will use digital pin modes when dealing with signals that are either "on" or "off", such as an LED, a switch, or another digital IC. Analog inputs are used when you want to read the voltage ...
woo2's user avatar
  • 101
5 votes

Programming standalone Atmega328p-PU with NE555N timer IC

No, you won't be able to build a 16 MHz clock signal using a 555 timer. That's far beyond the 555 capabilities (see N.B.). If you could squeeze out of the 555 a mere 1 MHz (which I seriously doubt), ...
Enric Blanco's user avatar
  • 2,114
5 votes
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What's in an Arduino?

You did not specify what Arduino board you are talking about. It would have been useful to tag the question with the appropriate board name. In the following, I assume you want something similar to an ...
Edgar Bonet's user avatar
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5 votes
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5V pin output on arduino

Time for a crash course in electronics and power: The 5V pin only ever provides 5V. That's why it's the "5V" pin. (assuming, of course, that you give the board more than 5V). In simple linear ...
Majenko's user avatar
  • 105k
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

Moving motion sensor?

OP didn't really specify the actual requirements other than detecting movement and wanting to use PIR while in motion. PIR (Passive Infrared) implies looking for warm bodies. In general, PIR ...
SDsolar's user avatar
  • 1,165
4 votes
Accepted

Getting the DS18B20 detected and temperature read

Vdd on the DS18B20 is not connected to anything. According to the datasheet: When the DS18B20 is used in parasite power mode, the VDD pin must be connected to ground Connect 5V from the Arduino ...
Nick Gammon's user avatar
  • 38.2k
4 votes

Programming standalone Atmega328p-PU with NE555N timer IC

Yes, you could use a 555. You can also go even simpler and use an RC network. Even simpler still is to use the 1MHz RC network built in​ to the chip. The main drawback of these methods, and the 555 ...
Majenko's user avatar
  • 105k
4 votes

Programming standalone Atmega328p-PU with NE555N timer IC

The default configuration of these chips, as they come from the factory, is to use their internal 8 MHz RC oscillator downscaled at 1 MHz. So you do not need any extra oscillator to program them. ...
Edgar Bonet's user avatar
  • 43.1k
4 votes

Can you use an input pin instead of ground in Arduino circuitry?

An input pin can only sense the voltage that is applied to it - whether it is above or below a pair of thresholds. In your existing circuit when the button is not pressed the voltage sensed by the ...
Majenko's user avatar
  • 105k
4 votes
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Is it possible to increase the voltage on 3.3v output to 5v on an ESP board to power a DC motor?

You should not power a motor from a micro-controller, period, regardless if that is an ATmega or an ESP32. Instead, you need to use a motor driver circuit - this isn't really so much about voltage ...
Chris Stratton's user avatar
4 votes
Accepted

Does AWG size affect signal from sensors?

A signal is just a varying voltage. A wire is just a (very long) small resistor. The device reading the signal is just a current sink. That's three terms there: voltage, resistance, and current. ...
Majenko's user avatar
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4 votes
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How do I know if I need to use a resistor in a circuit?

From the specifications of the sensor, you know the maximum current the sensor should be allowed to draw. Suppose you need to put 5v across the sensor. Then write down Ohm's law: E = IR (the voltage ...
JRobert's user avatar
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4 votes
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Is this circuit risky for an Arduino Uno?

That circuit is fine as long as the input signals don't go above 12.5V. You can protect it further by adding a 5.2V zener diode across each of the signals as they enter the Arduino: simulate this ...
Majenko's user avatar
  • 105k
4 votes

What exactly does the return type do in a function?

It returns it to whatever the function is being assigned to. Take the function: int plus(int a, int b) { return a + b; } That function takes two integers, adds them together, and "returns&...
Majenko's user avatar
  • 105k
4 votes
Accepted

Best way to add external power supply when main PSU is a solar charge controller?

Should I power the Arduino with the buck converter parallel to the same PSU (the 12V 20A Solar Charge Controller) I'm using for the pumps Yes. However I wouldn't use a 9V buck regulator, but a 5V one ...
Majenko's user avatar
  • 105k
4 votes
Accepted

How to calculate required amperage of multiple motors?

I don't know if the amperage is additive with each additional motor Yes, amperage is additive. the Arduino cannot handle over one amp but 0.24*5>1 That is correct. But the stepper motors should ...
chrisl's user avatar
  • 16.3k
4 votes

As a novice, how do I program my Atmega328p?

Are the ATMEGA and STM32 programmers not universal? They are not the same. As far as I know their programming arrangements are completely distinct. What programming methods can this chip support? ...
RedGrittyBrick's user avatar
3 votes
Accepted

Attach headers to servo wires?

What I do in situations like that is get some of those breadboard hookup wires, like you have in your second photo, cut them in the middle (giving yourself two wires, each with a bare end, and a end ...
Nick Gammon's user avatar
  • 38.2k
3 votes

How to run 5 wires hibrid stepper motor with arduino uno?

1) it is probably something like A1, A2, Common, B1, B2. You could confirm this with an ohmmeter. Common to any of the others would be a certain resistance X, while between any of the others (A1-A2, ...
Dave X's user avatar
  • 2,332
3 votes

Making three led's blink at different times in Arduino

Using a 220k Ohm resistor will lead to approximatively 20µA to light the LED. This is not enough to light the LED, you should replace the resitor by one of value 330Ohm (220 to 470 could be OK ...
Julien's user avatar
  • 201
3 votes

Programming standalone Atmega328p-PU with NE555N timer IC

It depends on how you're programming it. If you're using a bootloader to accept programming commands via a serial connection then you will need to use the clock method specified by the fuses ...
Ignacio Vazquez-Abrams's user avatar
3 votes
Accepted

In the AnalogRead example, would the thing work if I remove or short the A0 and the ground pin?

I think you are confused because the ADC input measures voltage, not resistance. To convert from resistance to voltage you need to pull in the opposite direction on the variable resistance with a ...
st2000's user avatar
  • 7,325
3 votes
Accepted

Powering on the PC

The two pins aren't +5V power and ground. One of them will be what you think, the other will be a signal wire with a pull up/down. So if the ground wire really is ground then the other wire is the ...
Andrew's user avatar
  • 1,050

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