Questions tagged [floating-pin]

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NE564 PLL chip operates on PCB only with loop filter pin 14 floating

This circuit has been implemented on my PCB. However, when I test this circuit (without the DRV135UA), it surprised me that the PLL works except Pin 14 of NE564D (V_PLL). At Pin 14, I did not measure ...
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4 answers
234 views

Can I leave an unused open-drain output disconnected?

I'm designing a circuit using the MAX22203 motor driver and it has a few open drain outputs to indicate current throttling. In my design I don't need to read these outputs, so my question is what ...
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2 votes
3 answers
2k views

Microcontroller Unused pins Configuration

I am having this microcontroller - S32K142 64 pin 5V core voltage I have a few pins which I don't want to use. While checking the datasheet of the Microcontroller, I couldn't find any information ...
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1 answer
145 views

Should an unused VCC pin with a higher voltage be left unconnected?

I'm trying to integrate an ESP32-PICO-KIT/V4.1. into a small project. The documentation for the PICO power supply says this: There are three mutually exclusive ways to provide power to the board: ...
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3 answers
229 views

Are there any disadvantages in high pin count MCU?

I have to choose a mcu for a project and I only need 4 I/O pins. However, microcontrollers with higher computational power usually have many pins. Are there any disadvantages using a high pin count ...
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1 answer
242 views

How to isolate sensor power and ground lines as simply as possible

I have an Arduino project that includes three sensors a EC, PH and PPM sensor. The problem is that when you read a sensor the other two sensors affect the reading of the current sensor due to the ...
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5 votes
3 answers
1k 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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1 answer
155 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'...
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1 answer
251 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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  • 835
0 votes
1 answer
755 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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  • 187
1 vote
1 answer
271 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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1 vote
5 answers
3k 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 ...
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3 votes
1 answer
129 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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0 votes
0 answers
618 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 ...
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0 votes
2 answers
123 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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2 answers
3k 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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0 answers
146 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 ...
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1 vote
2 answers
711 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 ...
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2 votes
1 answer
208 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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0 votes
1 answer
64 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 ...
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-2 votes
1 answer
60 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.
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3 votes
1 answer
3k 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 ...
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1 vote
1 answer
159 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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1 vote
3 answers
375 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 ...
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4 votes
1 answer
595 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 ...
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1 vote
1 answer
1k 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 ...
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10 votes
2 answers
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 ...
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0 votes
1 answer
95 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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1 vote
4 answers
975 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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-1 votes
2 answers
886 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 ...
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11 votes
2 answers
39k 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: ...
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6 votes
2 answers
545 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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1 vote
3 answers
2k 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 ...
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1 vote
2 answers
287 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 ...
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  • 3,464
21 votes
7 answers
5k 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 ...
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