GPIO (General Purpose Input Output) pins on a microprocessor can be configured as either inputs or outputs and can be enabled or disabled. As inputs, the pins can be read to determine high or low voltage levels, and as outputs, the pins can be written to drive high or low voltages. GPIO pins can also be configured to trigger interrupts on certain voltage changes to help trigger program responses. The functionality of GPIO pins is controlled through various registers that determine pin directions, read pin states, set output states, and configure interrupt behavior.

1. GPIO
General Purpose Input Output

2. GPIO ?
• Generic Pin of an Microprocessor / Microcontroller
• Can be configured as either input or output
• Can be enabled / disabled its operation
• Operating Levels
• HIGH
• LOW
• Output pins are writable and also can be readable
• Input pins are readable, writing over input pin
• Pins configured as Input also can operate as interrupt
• No Predefined operation / purpose

3. Functional Diagram
PORT x.n
Pin Data Register
PORT x.n
Pin Status Register
Port x
Pin n
Port x.n
Direction

4. Functional Registers
• GPIO Data Register
• Data in this register will be driven out to output pin
• GPIO Direction Register
• Controls the direction of GPIO either input or output
• GPIO Pin Status
• Contains the values of corresponding input
• GPIO Interrupt Configuration register
• Low level / High level / Rising edge / Falling edge sensitive
• GPIO Interrupt Mask register
• Enable / Disable the interrupt
• GPIO Interrupt Status
• Interrupt status indicates whether interrupt occurred or not

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