RDK X5 40-Pin Header: GPIO Setup, Pin Mapping, and Multiplexing Explained

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The RDK X5 development board features a Raspberry Pi-compatible 40-pin header that supports GPIO, I2C, UART, SPI, and PWM interfaces. The header operates at 3.3V logic only, with a maximum safe voltage of 3.46V per pin, and offers 800mA and 500mA current budgets on the 3.3V and 5V rails respectively. Several pins support multiplexing, allowing them to switch between dedicated peripheral functions and general-purpose GPIO, though changes require a reboot to take effect. Configuration is managed through the built-in srpi-config utility, which enables or disables peripheral buses via a menu-driven interface. A sample project using the board demonstrates basic GPIO operation by reading a button on pin 37 and toggling an LED on pin 31.

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