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Questions tagged [floating-pin]

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How long is it okay for pin to be floating during MCU startup?

I’m using an ESP32-S3 to communicate with a 5V-only LCD module with an i8080 parallel bus interface. To shift the levels, I’m using the SN74LVC8T245 bidirectional level shifter. This means I can both ...
Emil Eriksson's user avatar
1 vote
1 answer
227 views

Floating input pin error on my rover schematic of altium designer

I am receiving "contains floating input pins" errors on my altium designer schematic (among other issues) despite the wires being correctly connected, and each port and respective component ...
YouGotDecked's user avatar
0 votes
2 answers
81 views

FT232RL OSCI pin termination

How do deal with Input pins, which not in use. Have seen many examples, where they kept floating, but I don't like personally when an high-Z inputs kept floating in the design in some IC which I could ...
Pinus's user avatar
  • 95
6 votes
1 answer
259 views

What happens to GPIO pins that are not exposed in a (small) package?

In one of our projects, we use an STM32L071 MCU in an LQFP48 package. It exposes GPIO port pins PA0 to PA15, PB0 to PB15 and PC13 to PC15 on the pins of the package. The LQFP48 package doesn't expose ...
NZD's user avatar
  • 345
0 votes
1 answer
88 views

Circuit that holds a PIN to GND and leave it floating after power on

I need a simple circuit that during power on fixes a pin of an IC to GND and after a while leaves this pin floating. Another circuit should be the same, but fixing another pin to -VEE (-30 V) and then ...
mtx4's user avatar
  • 91
2 votes
1 answer
225 views

How does floating pin detection work?

On MCP34xx devices datasheet on page 2 it is written: The I2 C address bits for the MCP3427 and MCP3428 are selected by using two external I 2 C address selection pins (Adr0 and Adr1). The user can ...
php_nub_qq's user avatar
5 votes
1 answer
1k views

Why do we connect unused (always low pins) pins to GND through a resistor instead of connecting it directly to GND?

I have been reading the datasheet of RV-3028-C7. Everytime it talks about a pin that might be unused in a certain scenario (should be logic low), it instructs to connect the pin to ground through a ...
Mora's user avatar
  • 179
1 vote
0 answers
130 views

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 ...
Kwok's user avatar
  • 113
0 votes
4 answers
1k 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 ...
csiz's user avatar
  • 174
2 votes
3 answers
3k 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 ...
user avatar
0 votes
1 answer
255 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: ...
par's user avatar
  • 275
0 votes
3 answers
489 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 ...
pedrocklein's user avatar
0 votes
2 answers
719 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 ...
Edwin Martin's user avatar
5 votes
3 answers
2k 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 ...
Magnar Kleppe's user avatar
0 votes
1 answer
235 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'...
cubix's user avatar
  • 233
1 vote
1 answer
566 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 ...
Daniel's user avatar
  • 917
0 votes
1 answer
1k 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 ...
H123321's user avatar
  • 197
1 vote
1 answer
360 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 ...
Christophe Gudlake's user avatar
1 vote
5 answers
4k 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 ...
Greg Vercellotti's user avatar
3 votes
1 answer
176 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 ...
cheweyjunior's user avatar
0 votes
0 answers
883 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 ...
Shanee Vanstone's user avatar
0 votes
2 answers
147 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 ...
ARF's user avatar
  • 5,219
0 votes
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 ...
Mason's user avatar
  • 1
1 vote
0 answers
198 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 ...
DonnellyOverflow's user avatar
1 vote
2 answers
1k 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 ...
Matthew Shaile's user avatar
2 votes
1 answer
227 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 ...
Alexander M's user avatar
0 votes
1 answer
70 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 ...
turbonate's user avatar
-2 votes
1 answer
67 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.
Simon's user avatar
  • 51
3 votes
1 answer
4k 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 ...
dr3patel's user avatar
  • 1,652
1 vote
1 answer
173 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://...
avl_sweden's user avatar
  • 1,024
1 vote
3 answers
442 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 ...
pugnator's user avatar
  • 166
4 votes
1 answer
607 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 ...
anrieff's user avatar
  • 5,469
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 ...
Dan Laks's user avatar
  • 8,604
10 votes
2 answers
4k 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 ...
esal26's user avatar
  • 123
0 votes
1 answer
108 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 ...
OrangeCalx01's user avatar
1 vote
4 answers
1k 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-...
FlegmatoidZoid's user avatar
-1 votes
2 answers
1k 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 ...
Ollusaurus's user avatar
12 votes
2 answers
40k 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: ...
Guilherme Garcia da Rosa's user avatar
6 votes
2 answers
661 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 ...
AndrejaKo's user avatar
  • 23.5k
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 ...
RocketLauncher's user avatar
1 vote
2 answers
351 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 ...
bdutta74's user avatar
  • 3,534
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 ...
Vorac's user avatar
  • 3,143