Raspberry Pi Stack Exchange
Raspberry Pi Stack Exchange

Questions tagged [measuring]

Use this tag if your question relates to measuring, eg., via a sensor.

Measuring is the process of determining quantities.

55 questions
46
votes
6 answers

How do I measure the current power consumption?

Is it possible to measure (with software, like PowerTOP) the Pi's current power consumption, on my Raspberry Pi?
cupakob
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16
votes
3 answers

Measure RPi3 power consumption without external hardware

I power my RPi3 using a power bank for smartphones, and I'd like to check how much power the Pi draws from it while my project is running. I don't have any special equipment for power measurement. Is there any way to measure (or at least estimate)…
eden881
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8
votes
4 answers

How to detect whether there is voltage between two points via GPIO?

I'd like to detect whether an external device is switched on or off. I found two pins where there should be 5V between in the first case, but the voltage may vary a bit and I don't wont to break the Pi. How should I connect the points to GPIO pins…
Jakob
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6
votes
3 answers

Count RPM/Frequency/Pulses on GPIO ports (Maximum?)

I'm planning to count the RPM of a RC Car which is controlled with a PI B+. But while planning the question occurs, how to count the RPM. My Idea is via a Sensor, which gives a Pulse every Round, and to count that via Software. My Problem right now…
XoMEX
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5
votes
1 answer

Reading Frequencies with Python

hello ladies and gents. your knowledge helped me a lot until now but now i have a question. i want to read out the frequency of a 3.3V squarewave. (The unit i want to readout is a capacitive moisture sensor: SensorLink) the frequency the sensor puts…
Hansom DIY
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4
votes
5 answers

How to read values from an clamp-on ammeter with an raspberry pi?

I want to use a clamp-on ammeter (like this one) to detect whether a table saw (230V) is switched on or not. The clamp-on ammeter is meant to be used with a volt meter and has an 1 mVAC / A output signal. I'm looking for a way to hook the clamp-on…
BetaRide
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4
votes
5 answers

Voltage monitoring of battery pack (i.e. before voltage regulation)

I am looking to use four 18650 batteries and a step-down DC-DC converter to power my Raspberry Pi 4. The negative terminal of the DC-DC converter is common for the input and the output. I would like a way to monitor the voltage of the battery pack…
mr_tuna
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3
votes
1 answer

Does Raspberry Pi 3.0 support HDMI 2.0 standard?

I am not able to see specific protocol version of HDMI (1.4 or 2.0) supported by RPI 3.0. Basically I want to take HDMI 2.0 output from RPI and provide it to my device. Also can we measure the rate of output HDMI signal?
Ashish
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2
votes
1 answer

Why is my zero SPI clock frequency different than requested?

Using the SPIdev, I have setup the SPI clock frequency, but measuring the real signal frequency using oscilloscope shows, it differs extremely to the expectations. How is this possible? spi_fd = open(device, O_WRONLY); ret = ioctl(spi_fd,…
sharpener
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2
votes
2 answers

Measuring frequency via GPIO

I'm trying to input the frequency of a 3.3V square wave on a GPIO pin as a program feedback parameter. The input frequency range would be 1000 to 100,000 Hz and data polling would happen at 30 Hz. Its important to minimize processor overhead. We…
Jim Sears
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2
votes
2 answers

How to measure DC current RPi?

I have recently bought a Raspberry Pi, and I would like to be able to measure the current flowing through the circuit in our Greenpower electric racing car. It would also be useful to record this for future analysis, ideally using Python. I have…
theAlex
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2
votes
1 answer

Can GPIO measure 3-10ms input spike?

I want to measure speed with one infra gate. The width of the bypassing object is known therefore I could calculate the speed. However the infrared gate would be interrupted only for 3-10ms. I understand raspi is not real time but it doesn't matter…
Andras Csehi
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2
votes
2 answers

Frequency counter with external reference

I'd want to use the RPi-pico to measure the ratio between two frequencies, one stable F0 = 10MHz, the other F1 about 14MHz, both externally fed to two GPIOs. 20 bit accuracy is fine. That could be e.g. counting over 21 bits how many F1 pulses there…
fgrieu
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2
votes
1 answer

Direct reading from i2c

I am attempting to increase the frequency at which I read samples from the I2C dedicated pins. I have attempted this through the wiringPi library (C code), from which I reached just about 900Hz. As well as with python, I was able to reach roughly…
theeddible
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2
votes
2 answers

Measure Volt, Amps, Watt and Kwh of an external 12V system

I saw online some cheap hardware ~10$ that can measure Volt, Amps, Watt and Kwh and display the results on an LCD screen. I could buy and plug these on my 12V solar panel system to monitor it. (5 of them) But thinking about it, I wish to use my RPI…
bob dylan
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