Questions tagged [floating-pin]

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3answers
97 views

Why does a pull down resistor eliminate floating input

Ever since I connected a button to an Arduino for the first time, I've wondered how does the resistor prevent floating input from happening? I've read several answers to similar questions, seen videos ...
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1answer
45 views

summing amp - floating inputs

I'm designing an audio mixer and currently i'm working on a cue section. The whole point is that i have 2 or more channels and want to mix them in summing mixer. You can turn off the channels you don'...
1
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1answer
46 views

Can I leave it unconnected pins in the level shifter?

My concern is that pins are connected between DB25 and TXS0108E, but are not connected between TXS0108E and the Header 5x2. There is only the tracks between TXS0108 and the Header 5x2, but there is no ...
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1answer
105 views

Can I leave the input pins of an ADC channel in floating state?

I'm using this 4-channel ADC: MCP3422 -> Datasheet I only need to use 3 of the available 4 input channels in total. Normally I would add footprints for pulldown resistors for example in case a ...
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1answer
150 views

Floating analog input using Arduino with 1m cable

I use an analog input from an Arduino to read the value from a piezo plugged in parallel with a 1M ohm resistor. I followed this tutorial from Arduino: https://www.arduino.cc/en/Tutorial/Knock Here ...
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5answers
503 views

How to measure voltage of a floating GPIO (Raspberry Pi)

I would like to measure that voltage of a floating GPIO on a Raspberry Pi 3. When I use a multi meter or an oscilloscope it looks like the pin is pulled to ground and shows 0. Another way of asking ...
3
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1answer
86 views

What should I do to unused input parts/features (analog and digital input pins, and power pins) of a video scaler chip?

I am working on a video scaler chip which has multiple inputs (i.e HDMI, DP, VGA) but I only want to use the VGA input. (Choosing another chip with only one input is not an option). The friendly ...
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0answers
261 views

Can I leave bootstrap pins floating? (Internal pull-up)

I have a microcontroller that uses 4 GPIO pins as "bootstrap pins". The state of these pins (high/low) at boot time will determine important features of the microcontroller, such as output voltage to ...
0
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2answers
101 views

Switch to make MCU pin float [closed]

I have an application where I need to make a ADC input pin (0-1V) float controlled by GPIO (any connect it in other cases to its input obviously). I was considering a transistor in-line with the ADC ...
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2answers
2k views

Sensing Voltage with a Digital Pin

I am relatively new with Arduino and did a little bit of research prior to this post. But I am trying to sense when I have voltage coming from an AC/DC converter (12Vdc) so I can switch from my ...
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0answers
98 views

momentary push switch triggering twice

I have a momentary push switch connected to my mbed microcontroller. The switch is used to trigger an interrupt which changes a setting on the device. At the moment the button works around 70% of ...
1
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2answers
433 views

Floating value when connecting to IC input

I'm currently having a strange issue with what I think is a 'floating' signal. The setup: I have a bank of inputs (which are connected to a resistor and LED acting as a pull-down) connected to inputs ...
2
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1answer
188 views

Floating Vdd; NV Pokemon saves [closed]

http://forums.benheck.com/viewtopic.php?f=18&t=38664 In the link, there is a thread discussing replacing gen 1&2 Pokemon cart sram ICs with fram equivalents. The only differences between old ...
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1answer
58 views

In Transient Analysis, what happens when free electrons are applied to a matrix of resistors that don't have a ground?

I'm trying to figure out what happens to a 30 Volt supply when it is attached to a circuit of resistors which are not grounded. I know that eventually (steady state) the voltage of the circuit should ...
-2
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1answer
52 views

What determines the # of pins of a cmos Imaging sensor?

Why do some cmos Imaging sensors have 48 pins and others 36 and some 34...e.c.t? I'm new to these sensors and I don't really understand the connectivity differences.
3
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1answer
2k views

What should I do with the unused Op-amp inputs? [duplicate]

I am building a simple inverting operational amplifier circuit where I am using a chip with dual amplifier. I am only using one of the two amplifiers. What should I do to the unused amplifier's input ...
0
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1answer
125 views

Leave Darlington inputs unconnected

I'm designing a relay-driver board with 15 double throw relays. I'm using shift registers to save IO-pins on the CPU. The shift registers feed into darlington ST ULN2003A transistor arrays: http://...
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2answers
329 views

Bus value if some pins are floating

I'm working on plugin for simulation software (digital IC only). For example there is 8 bit bus. User wants to read it's value. On plugin side I check each pin's state. It can be 1, 0 or undefined. At ...
4
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1answer
580 views

How can moving my foot possibly affect electronics meters away?

I'm curious about a strange effect I observed. I was designing a device, which sleeps most of the time and can be woken up by a loud sound signal, like an opening door, a clap, etc. The relevant ...
1
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1answer
636 views

Floating a digital output pin of an IC

I'm using a FXLS8471Q accelerometer for a project using the SPI interface. The chip uses the same pins for SPI and I2C. To detect which interface the user desires, the chip samples the SA0 pin on ...
10
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2answers
3k views

What to do with unused analog inputs?

I am working on an application using ATmega328p atmel microcontroller. I started with the 28 PDIP version, but now I want to use the 32 TQFP, which I noticed has 2 extra inputs after compiling my ...
0
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1answer
77 views

Floating EEPROM (28c64A) pins an option?

I am building an eeprom programmer for the 28C64A (dip package) with my old basic stamp ii "homework" board (lost my arduino in the move). I have the first four address and data pins, as well as W E ...
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4answers
729 views

MOSFET gate grouding via LED - noise

simulate this circuit – Schematic created using CircuitLab I use D1 to visually indicate the active transistor. However, gate pin acts as if it were floating. What is wrong with my gate-...
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2answers
630 views

Getting rid of floating input in a logic level converter

Is it possible to make the output of this circuit 0V, when the input is floating as shown in the picture . I tried adding a pulldown resistor to the input, but it only worked at a very low value(100 ...
9
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2answers
32k views

Arduino digitalRead reading wrong

I have set up my Arduino UNO with 4 input wires, they connect to the port 10, 11, 12, 13, they are connected to my breadboard with nothing on it but the wire. My code would simply be: ...
6
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2answers
399 views

What's the benefit of not soldering NC pins compared to soldering them to a disconnected pad?

I've been looking at my scope's power supply board and I noticed that R7731A "Burst Triple Mode PWM Flyback Controller" in DIP has two NC pins which are not connected to absolutely anything. They've ...
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3answers
825 views

Can a pull down be used to tie a line to ground?

From my recent introduction to pull-up/pull-down resistors, I understand that an input with a pull-down will stay low instead of floating. Since the pull-down resistor leads to ground, couldn't I ...
1
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2answers
270 views

How and why is “floating input” a valid state for RF/IR encoder IC's?

RF/IF encoder/decoder IC's such as this one, will accept the address-pin in one of 3 states: Floating High Low As per this excellent answer, I believe "Floating" input can assume either High or Low ...
22
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7answers
4k views

Random number generators using a GPIO pin?

I just read through question AVR Random Number Generator and encountered a number of ways to generate random seeds in an AVR: Use a special-purpose "Secure AVR" Use an internal temperature sensor ...