I have a dc dc regulator which can output .35A Current at 3.3V. I just need to check that the voltage it is producing is 3.3V by connecting it's output into one of the GPIO pins of Pi. So i was wondering what is the easiest way to do it, will a series resistor do the job. And what would be the value of it.
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\$\begingroup\$ Do you want to measure the exact value of the supply voltage (x.xx V), or do you simply want to sense if the supply voltage is present (on/off) ? \$\endgroup\$– marcelmCommented Feb 5, 2019 at 11:18
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3 Answers
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just need to check that the voltage it is producing is 3.3V by connecting it's output into one of the GPIO pins of Pi.
No, that is NOT the way to check the voltage. Beside the chance of damaging the Pi, even with resistor, the Pi can not tell you what the voltage is.
Buy a Volt meter. Nowadays you get a good universal meter for as little as $10. (I bought five** good ones for $5 each, a few years back).
If you want to continue dabbling in electronics you are going to need one.
**I gave some to family so when I visit and they ask me to 'look at my...' I have a meter to do it. I once managed to guide my parents by phone to use one and find the fault in a cable.
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That sounds iffy. I would use something with an inbuilt ADC such as an Arduino. If you have something like a 1K resistor on hand then put that in series with it just in case. If you have some diodes they would be best, placing one with the negative side on the power supply you are measuring and the positive side to the power supply of the Arduino. Equally if you are just looking for a number (i.e. not constant monitoring) then buy yourself a multimeter online. That being said it can be a good project to make your own at home!
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If you want your Pi to tell you the output voltage of your DC/DC regulator you'd need to use an external analogue-digital converter (ADC).
