8.3.8 GPIO Signal Operation

The LP8756x-Q1 device supports up to 3 GPIO signals. The GPIO signals are multiplexed with enable signals. The selection between enable and GPIO function is set with GPIOx_SEL bits in PIN_FUNCTION register. The GPIOs are mapped to EN signals so that:

• EN1 is multiplexed with GPIO1
• EN2 is multiplexed with GPIO2
• EN3 is multiplexed with GPIO3

When the pin is selected for GPIO function, additional bits defines how the GPIO operates:

• GPIOx_DIR defines the direction of the GPIO, input or output (GPIO_CONFIG register)
• GPIOx_OD defines the type of the output when the GPIO is set to output, either push-pull with VANA level or open-drain (GPIO_CONFIG register)

When the GPIOx is defined as output, the logic level of the pin is set by GPIOx_OUT bit (in GPIO_OUT register).

When the GPIOx is defined as input, the logic level of the pin can be read from GPIOx_IN bit (in GPIO_IN register).

The control of the GPIOs configured to outputs can be included to start-up and shutdown sequences. The GPIO control for a sequence with ENx signal is selected by EN_PIN_CTRL_GPIOx and EN_PIN_SELECT_GPIOx bits (in PIN_FUNCTION register). The delays during start-up and shutdown are set by GPIOx_STARTUP_DELAY[3:0] and GPIOx_SHUTDOWN_DELAY[3:0] bits (in GPIOx_DELAY register) in the same way as control of the regulators.

The GPIOx signals have a selectable pulldown resistor. The pulldown resistors are selected by ENx_PD bits (in CONFIG register).