Event Capture Module - Texas Instruments OMAP5910 Technical Reference Manual

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Event Capture Module

Figure 7–15. GPIO_CLK Timing

The GPIO event capture mode allows latching the input value present on

the GPIO ports each time a rising or a falling edge occurs on a selected GPIO

port, here called GPIO_CLK. If not masked, the GPIO_CLK-selected edge

generates an interrupt to the processor, as shown in Figure 7–15.

GPIO_CLK can be generated from an external physical module. Consequent-

ly, it may be necessary to insert a debouncing delay on this signal. The

debouncing time is programmable in the GPIO debouncing register

(GPIO_DEBOUNCING_REG) in steps of 31 µs.

The GPIO event mode register (GPIO_EVENT_MODE_REG) enables or

disables the GPIO event mode. It also selects the external pin used as the

GPIO_CLK. The GPIO interrupt edge register (GPIO_INT_EDGE) selects the

GPIO_CLK falling or rising edge to generate the GPIO_INT interrupt.

When the gpios_int interrupt (active low) is generated, the GPIO_INT register

must be read by the MPU to define any active GPIO signal interrupts.

The GPIO interrupt mask register (GPIO_MASKIT) masks GPIO interrupts

individually.

On the GPIO_CLK programmed edge, after the debouncing delay, the internal

MPUIO_IN bus is latched in the GPIO latch register (GPIO_LATCH_REG). Its

value can be read after the detection of the interrupt, even if the external value

has changed.

The event capture process is shown in Figure 7–16.