RM0360 Datasheet, PDF (131/727 Pages) STMicroelectronics – This reference manual targets application developers

General-purpose I/Os (GPIO)
RM0360
8.3.8
8.3.9
External interrupt/wakeup lines
All ports have external interrupt capability. To use external interrupt lines, the given pin must
not be configured in analog mode or being used as oscillator pin, so the input trigger is kept
enabled. Refer to Section 11.2: Extended interrupts and events controller (EXTI) Refer to
and toSection 11.2.3: Event management.
Input configuration
When the I/O port is programmed as input:
• The output buffer is disabled
• The Schmitt trigger input is activated
• The pull-up and pull-down resistors are activated depending on the value in the
GPIOx_PUPDR register
• The data present on the I/O pin are sampled into the input data register every AHB
clock cycle
• A read access to the input data register provides the I/O state
Figure 15 shows the input configuration of the I/O port bit.
Figure 15. Input floating/pull up/pull down configurations
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131/727
DocID025023 Rev 2