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Is there any way to use a normal GPIO pin as a 5V output pin? I am using a screen that prevent access to all power outputs, so I have only the normal GPIO pins and ground pins, not mentioning the id_sc and id_sd pins. Also what do they do?

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All the GPIO are 3V3. I suppose you could use a voltage converter but remember each GPIO can only supply about 20 milliamps.

The ID_SC and ID_SD are I2C bus 0. They are reserved for HAT and system usage (unless you know what you are doing).

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GPIO are not meant to supply much power. I believe the limit is 20 ma at 3.3v on the Pi. This isn't just for the Pi, but every microcontroller and microcomputer chips I've known about (other chips may have different voltages and limits) Of course, I don't know about all chips. But basically it would be a good way to destroy the Pi.

A possible solution would be to put a prototyping hat with an extra-long header between the Pi and your screen, and take the power from that. Or, if you're willing to solder, then you can solder to the bottom of the header on the Pi, but you have to know what what you're doing.

A better solution would be to use another power supply. You would need to join the grounds, though.

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A "logic level converter" will allow you to convert the 3v3 I/O pins on the Pi to 5v ttl level. These are commonly available from vendors that make hobbyist or "maker" electronic modules, such as SparkFun and Adafruit. These devices typically have to be connected to power on both sides (3v3 on the Pi side, 5v on the device side). You will have to read the specs of the device to decide if the 5v circuit will have enough drive to power whatever you are trying to switch on and off.

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  • I don't think level shifters are intended to (or capable of) the current amplification that's implied here. They're for signalling (hence logic level shifter), not power. In other words, if you have a 3.3V 10 mA current stepped up to 5V, it cannot necessarily supply as much current as the 5V input. – goldilocks Jul 2 '18 at 19:01
  • I suspect you are right, though the logic level shifters I have used require a +5vdc source on the "device" side. The Adafruit one, for instance, uses a TI TXB0108 chip, which can provide 50 mA total output across all 8 output pins, and would need a +5v on Vccb. – softweyr Jul 2 '18 at 20:12
  • It doesn't have to do with what label there is on the 5V input. It has to do with how the signal is passed through transistors. There are a lot of restrictions regarding how much current can be passed through, e.g, bipolar junction transistors in relation to their base. So the issue is not the 5V supply, the issue is the amount of current supplied to the signal lines on the low side input. Unless you build that circuit specifically to amplify the 3.3V signal current using the 5V power, it isn't going to happen. – goldilocks Jul 3 '18 at 11:05
  • I'm not your downvote, BTW, so I suspect someone else sees what I see here -- you're handing out some bad advice. See: electronics.stackexchange.com/q/42727/52138 – goldilocks Jul 3 '18 at 11:05

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