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There are two ways to connect a LED to light it with a GPIO. connect the anode to a GPIO and the cathode to ground. The LED will light when the GPIO is high and go off when the GPIO is low. connect the cathode to a GPIO and the anode to 3V3. The LED will light when the GPIO is low and go off when the GPIO is high. I am ignoring the resistor which will be ...


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Q1: In the setup function of the python script, the GPIO pins are initialized as output pins in HIGH mode which defaults to the LEDs being off. I do not understand this behavior. Why does sending constant 3V3 power to a pin in output mode (specifically set to HIGH) result in the LED not turning on? A1: Looking "inside" a GPIO pin reveals a ...


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Your question is not Pi specific; indeed it is a general EE question. This circuit 3.3V - resistor - LED - GPIO is the normal (and recommended) method which would be used by most engineers. You appear to have a common misconception that there is something magical about positive voltages. The LED will light whenever there is a potential difference across it; ...


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I've used my RPi 3B+ recently in a solar-powered application. This answer is based on my experience. You must add a Real Time Clock using external hardware Without external hardware, is not possible to turn any currently available RPi ON or OFF at a designated time. If you want to do this, you will need a Realtime Clock (RTC). My approach to Add a Real-Time ...


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Raspberry Pi Trading (RPT) has recommendations for various models which range from 700mA to 3.0A. For the Pi4 "Typical bare-board active current consumption" is 600mA https://www.raspberrypi.com/news/thermal-testing-raspberry-pi-4/ Shows comparison of Pi3B+ & Pi4. Without anything connected to Raspberry Pi 4’s USB 3.0 ports and the latest ...


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When in headless mode, you can read out the diagnostic messages through the command line. If there is undervoltage, the dmesg command will output something like: ... [47124.394081] Under-voltage detected! (0x00050005) [47128.554071] Voltage normalised (0x00000000) [47423.915258] rpi_firmware_get_throttled: 1 callbacks suppressed [47423.915267] Under-voltage ...


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