A voltage that is not connected by any conducting path (including resistors) to ground or the key voltage reference point.
Questions tagged [floating]
139 questions
17
votes
8 answers
What is the right way to float a home lab?
I just got myself some new toys for my lab at home like 30V DC power supply, KKmoon signal generator and a Rigol DS1052E. I want to float everything, because I don't want to spend any money on stuff like differential probes or isolation…
Asians never die
- 173
- 1
- 4
14
votes
6 answers
Is a pull up/down resistor really necessary?
Logical reading (1 or 0) of a micro-controller input GPIO pin may float if it is neither connected to VCC nor GND; someone said it is because of surrounding RF interference.
When a floating GPIO input pin voltage is affected by RF interference that…
mannok
- 481
- 4
- 10
12
votes
2 answers
Floating multiple sealed lead acid batteries in parallel
I know with multiple lead-acid batteries you should really charge them separately so that one battery doesn't try and charge another and waste power.
But that holds true for the main charging process.
What about the "float" portion of the charge?
I…
Majenko
- 55,955
- 9
- 105
- 187
11
votes
5 answers
Confusion about the meaning of floating
Here they define being floating as:
They mention Ungrounded = Floating.
But in another forum someone wrote:
The signal is consider floating when it does not have the same ground
with your device. Earth has nothing to do with it. Earth is just
…
user1245
- 3,955
- 4
- 37
- 87
9
votes
7 answers
Why can a MCU input floating pin easily change state?
I would like a technical ("engineering") explanation of why a MCU input floating pin can easily change its state depending on the outside electromagnetic interference.
Is it related to the fact that the pin is in a high impedance state? If so, how…
Federico Toso
- 251
- 1
- 3
8
votes
3 answers
How can I float a pin that otherwise should be low?
I want to enable/disable a TI TPS54302 buck regulator with a microcontroller. The enable (EN) pin should float to enable the device, or be tied low to disable it.
I currently have the EN pin connected to a GPIO pin on the MCU. At startup, before the…
JYelton
- 32,302
- 33
- 134
- 249
7
votes
3 answers
Tying open-collector outputs to TTL inputs
I know that open collector outputs are effectively either 0 V or high-Z.
I also know that TTL chips tend to read a disconnected output as high, but that really you should have something like a 1 kΩ pull-up resistor for safety.
But does the warning…
Rob Simmons
- 173
- 4
6
votes
2 answers
Counting signal switching between floating and LOW in Arduino
I have a rotating contact (contact breaker of an ICE) that switches between being not connected to anything (floating) and being connected to the case of the ICE. The engine case is connected to ground (same ground as the Arduino). Thus the signal…
Yanick Salzmann
- 354
- 1
- 12
6
votes
1 answer
why trace_printf("%f",x); triggers a HARD FAULT on a stm32 MCU?
I'm using a stm32 F413ZH microncontroller with HAL libraries (mainly written to be used with c but can also be used with c++) in eclipse, actually I managed to completely configure eclipse including semihosting and debug mode(openOCD), the basic…
6
votes
7 answers
Getting two (or, one and a half) outputs from a single pin
I am doing a project with an ATtiny85 and of course I'm short on I/O pins. One idea I had was to use a single pin for two outputs (let's call them EN and DATA).
simulate this circuit – Schematic created using CircuitLab
I know that DATA doesn't…
Paolo Bonzini
- 163
- 7
6
votes
4 answers
Why would you need a floating signal on a board?
I read the following from a book titled "An Embedded Software Primer" by David E. Simon. (23rd print Nov/2014 - Page 16)
If no part on the circuit is driving a signal, then that signal is
said to be floating. Its voltage will be indeterminate…
M. A. Kishawy
- 419
- 4
- 10
6
votes
1 answer
What to do with unused TTL and CMOS outputs?
Just about everything I've read on the Web, including on this site, say that unused TTL and CMOS outputs should be left floating. However, this TI article, Designing with Logic, states:
Unused outputs of a device should not be left unconnected…
mbmast
- 379
- 3
- 12
6
votes
3 answers
How to check if a DC power supply is a floating source?
Imagine a laptop power supply with 2 prongs and I'm using this as a power supply for a circuit, and the output of this circuit is an input signal Vin for a data acquisition hardware.
How can I verify if this signal is floating?
My idea is to apply…
user16307
- 11,802
- 51
- 173
- 312
5
votes
2 answers
Coupling floating differential inputs to an amplifier with/without resistor pair
My question is about wiring a "floating differential input" signal to an instrumentation amplifier.
I've read that in the case of a floating signal two high value resistors are used to provide DC bias for the amplifier inputs as shown in Figure 1…
ty_1917
- 949
- 1
- 5
- 20
5
votes
3 answers
Confused about opamp's inner "ground"
(well. I am NOT speaking of "virtual ground" throughout this question/)
As this figure has shown an opamp can be viewed as:
We all know that an opamp like this has two inputs and one output - the input voltage is simply the voltage between the two…
gudako
- 183
- 6