I've connected a LED inclusive series resistor to GPIO3 (Pin 5) as the picture below shows (Raspberry Pi Model B Revision 2.0).

Once the power cord is connected to the Raspi, the LED lights up. This behavior differs from other GIPOs like GPIO17, 27, 22, 10, 09, 11 and so on. When I connect my LED with one of these GPIOs, the LED initially is off. Then I can turn on/off it with Python.

The question is, how can I control the GPIO3? I want to power on/off this pin (e.g. by Python) just as the other pins.

It is not just about GPIO3 at pin 5. The behavior of GPIO2 (pin 3) and GPIO14 (pin 8) is the same. These pins I would also turn on/off.

Thanks in advance


P.S.: The principle of the controlling the GPIO pins using Python is known to me.

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1 Answer 1


GPIO 2 and 3 (pins 3 and 5) have hard-wired 1k8 resistors to 3V3 attached (the resistors are needed for the correct operation of the I2C bus which uses those GPIO).

More than enough current will flow through the resistors to light a LED.

If the LED behaviour concerns you then use different GPIO.

You can still use the GPIO as normal as long as you bear in mind the hard-wired pull-ups.

GPIO 14 (pin 8) is the serial UART TXD and is enabled at boot for messages. The default state for a serial link TXD line is high. You can disable this behaviour with the raspi-config program (sudo raspi-config).

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