Questions tagged [measuring]

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

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Fluctuating SCLK voltage with increase in frequency

Raspberry pi newbie here. As part of my academics i was working on Raspberry Pi 3 B+ , Raspbian OS kernel 4.14.98-v7 and i was testing protocols and i am stuck at SPI. I am running spidev_test.c from ...
8
votes
3answers
7k views

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 ...
7
votes
2answers
23k views

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 ...
16
votes
2answers
3k views

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 ...
0
votes
1answer
499 views

How to measure mains frequency safely via GPIO

I would like to measure the mains power (120vac/60hz) to know precisely when the voltage drops to 0, but in a safe manner for the pi - one solution would be to use a high-value resistor bridge that ...