====== General Purpose Output ======

  * The [[#OTYPER|output buffer]] is enabled (open drain or push-pull).
  * The Schmitt trigger input is active.
  * The pull-up and -down resistors are active, according to [[#registers|PUPDR]].
  * Input data is sampled every AHB clock.
  * Input data register holds I/O state.
  * Output data register holds last written value.

\\ {{gpio_output.svg}} \\ \\

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

==== Enable Peripheral ====

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

==== Setup output mode ====

Configure the MODE and PUPDR as well as the output type and speed register, \\ for every pin that should act as digital output:
  * Write ''0x01'' to the corresponding fields in ''GPIOx->MODE''.
  * Configure pull-up / -down in ''GPIOx->PUPDR''.
  * Configure output type in ''GPIOx->OTYPER''. \\ (in conjunction with ''GPIOx->PUPDR'')
  * Configure output speed in ''GPIOx->OSPEEDR''.
\\

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

==== GPIOx_MODER - Port mode register ====

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

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|Pin x|01|Output mode|

==== GPIOx_PUPDR - Port pull-up / pull-down register ====

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

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|Pin x|00|No pull-up, pull-down (reset state)|
|:::|01|Pull-up|
|:::|10|Pull-down|
|:::|11|Reserved|

==== GPIOx_OTYPER - Port output type register ====

\\ {{gpio_reg_otyper.svg}} \\ \\

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|Pin x|0|Output type: push-pull (reset state)|
|:::|1|Output type: open-drain|

==== GPIOx_OSPEEDR - Port output speed register ====

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

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|Pin x|00|Speed: 2 MHz (reset state)|
|:::|01|Speed: 10 MHz|
|:::|10|Speed: 50 MHz|
|:::|11|Speed: 100 MHz|

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

==== GPIOx_ODR - Port output data register ====

\\ {{gpio_reg_odr.svg}} \\ \\

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|ODx|0|Clear/reset pin x|
|:::|1|Set pin x|

==== GPIOx_BSRR Port bit set / reset register ====

\\ {{gpio_reg_bsrr.svg}} \\ \\

|< 100% 5em 5em >|
|BSx|0|No effect|
|:::|1|Set pin x|
|BRx|0|No effext|
|:::|1|Clear/reset pin x|