====== General Purpose Input ======

  * The output buffer is disabled.
  * The Schmitt trigger input is active.
  * The pull-up and -down resistors are active, according to [[#PUPDR|PUPDR]].
  * Input data is sampled every AHB clock.
  * Input data register holds I/O state.

\\ {{gpio_input.svg}} \\ \\

===== Programming Instructions =====

==== Enable Peripheral ====

Make sure the peripheral is enabled:
  * Enable GPIOx in ''RCC->AHBENR[0]''.

==== Setup input mode ====

Configure the MODE and PUPDR register, for every pin that should act as digital input:
  * Write ''0x00'' to the corresponding fields in ''GPIOx->MODE''.
  * Configure pull-up / -down in ''GPIOx->PUPDR''.
\\

===== Configuration Registers =====

==== GPIOx_MODER - GPIO port mode register ====

\\ {{gpio_reg_common.svg}} \\ \\

|< 100% 5em 5em >|
|Pin x|00|Input mode (reset state)|

==== GPIOx_PUPDR - GPIO port pull-up / pull-down register ====

\\ {{gpio_reg_common.svg}} \\ \\

|< 100% 5em 5em >|
|Pin x|00|No pull-up, pull-down (reset state)|
|:::|01|Pull-up|
|:::|10|Pull-down|

===== Data Registers =====

==== GPIOx_IDR - Port input data register ====

\\ {{gpio_reg_idr.svg}} \\ \\

* Register is read only \\ \\