Contents
What do you need to know about GPIO protection?
Things we need to protect: 1) Drawing excess current from the pins (or short-circuiting an output) 2) Driving over-voltage on an input pin (anything above 3.3V should be avoided).
What do GPIO pins do on a Raspberry Pi?
While the GPIO pins can provide lots of useful control and sensing ability to the Raspberry Pi, it is important to remember they are wired directly into the internal core of the system.
What is the direction of a GPIO signal?
The GPIO direction register (DIR) specifies the direction of each GPIO signal. Logic 0 indica tes the GPIO pin is configured as output, and logic 1 indicates input. When configured as output, writing a 1 to a bit in the set data register drives the corresponding GPn to a logic-high state.
What causes a GPIO diode to break down?
By placing the diode between the GPIO pin and Gnd, any voltage applied which is greater than 3.3V will cause the Zener diode to “break down” (allow current to flow) through diode to Gnd (ensuring the voltage that reaches the GPIO is no more than 3.3V.
Do you need to protect the GPIO pins on Raspberry Pi?
Extreme caution should be exercised when interfacing hardware at a low level, you may damage your RPi, your equipment and potentially yourself and others. Doing so is at your own risk! In order to protect the Raspberry Pi hardware, it is highly recommended that the GPIO pins are protected in some form to avoid damage.
Is the GPIO Header Pin protection in both directions?
An advantage of this circuit is that the protection is in both directions, for both input and output modes of the pin, because the resistor also prevents the pin from overloading and shorting to ground. One disadvantage is the resistance keeps logic 0 voltage slightly above ground, which on a rare occasion poses an issue with non-Schottky TTL IC.
Is there header pin protection for Raspberry Pi?
Raspberry Pi GPIO Header Pin Protection The GPIO pins connect directly to the BCM2835 processor, which makes the system extremely sensitive to overvoltage, and overloading. This is a 3.3 V system and the pins are not 5 V tolerant. Feeding the pins 5 V from an external TTL circuit will damage them.