1.16.8 General Purpose I/O (GPIO)
General purpose I/O pins are the simplest of peripherals. They allow the PIC32MX family device to monitor and control other devices. To add flexibility and functionality, some pins are multiplexed with alternate \function(s). These functions depend on which peripheral features are on the device. In general, when a peripheral is functioning, that pin may not be used as a general purpose I/O pin.
Some of the key features of the I/O ports are:
-
Individual output pin open-drain enable/disable
-
Individual input pin weak pull-up and pull-down
-
Monitor selective inputs and generate interrupt when change in pin state is detected
-
Operation during Sleep and Idle modes
-
Fast bit manipulation using CLR, SET and INV registers
Using The Library
The GPIO peripheral library provides two kinds of functions which can be used to control GPIO Pins:
-
Pin Functions.
-
Port Functions.
Pin functions take a particular pin as input and operates only on that pin without affecting any other pins. Whereas port functions can operate on multiple pins of the same port together.
The GPIO peripheral library can generate a callback on a pin interrupt if the pin interrupt is enabled in the MHC.
Library Interface
General Purpose I/O peripheral library provides the following interfaces:
Functions
| Name | Description |
|---|---|
| GPIO_Initialize | Initialize the GPIO library |
| GPIO_PortRead | Read all the I/O lines of the selected port port |
| GPIO_PortWrite | Write the value on the masked I/O lines of the selected port |
| GPIO_PortLatchRead | Read the latch register value of the selected I/O port |
| GPIO_PortSet | Set the selected IO pins of a port |
| GPIO_PortClear | Clear the selected IO pins of a port |
| GPIO_PortToggle | Toggles the selected IO pins of a port |
| GPIO_PortInputEnable | Enables selected IO pins of a port as input |
| GPIO_PortOutputEnable | Enables selected IO pins of a port as output(s) |
| GPIO_PortInterruptEnable | Enables IO interrupt on selected IO pins of a port |
| GPIO_PortInterruptDisable | Disables IO interrupt on selected IO pins of a port |
| GPIO_PinWrite | Set the logic level of the selected pin |
| GPIO_PinRead | Read the selected pin value |
| GPIO_PinLatchRead | Read the value driven on the selected pin |
| GPIO_PinToggle | Toggles the selected pin |
| GPIO_PinSet | Sets the selected pin |
| GPIO_PinClear | Clears the selected pin |
| GPIO_PinInputEnable | Enables selected IO pin as Digital input |
| GPIO_PinOutputEnable | Enables selected IO pin as Digital output |
| GPIO_PinInterruptEnable | Enables IO interrupt on selected IO pin |
| GPIO_PinInterruptDisable | Disables IO interrupt on selected IO pin |
| GPIO_PinInterruptCallbackRegister | Allows application to register callback for every pin |
Data types and constants
| Name | Type | Description |
|---|---|---|
| GPIO_PORT | Enum | Identifies the available GPIO Ports |
| GPIO_PIN | Enum | Identifies the available GPIO port pins |
| GPIO_PIN_CALLBACK | Typedef | Pointer to a GPIO Pin-Event handler function |