STM32 GPIO Lecture 19 : Alternate functionality setting of GPIO pin with example

 

 

Alternate functionality setting of GPIO pin with example

 

When GPIO pin is in alternate functionality mode, it can be used for 16 different functionalities from AF0 to AF15. These possible 16 different functionalities are, used for system-related tasks, used by the timer peripherals, used by SPI or I2C peripherals and also for audio interfaces. 

 

Alternate functionality
Figure 1. 16 Different Alternate functionalities

 

Example: List out all 16 possible alternate functionalities supported by GPIO port ‘A’ PIN ‘8’ (GPIOA.8)

For GPIOA.8,

For AFO: MCO1 

For   AF1: TIM1_CH1. 

For   AF2: – (Not defined, behaves as standard GPIO).

For   AF3: – (Not defined, behaves as standard GPIO).

For   AF4: – I 2C3_SCL.

For   AF5: – (Not defined, behaves as standard GPIO).

For   AF6: – (Not defined, behaves as standard GPIO).

For   AF7: – USART1_CK

For   AF8: – (Not defined, behaves as standard GPIO).

For   AF9: – (Not defined, behaves as standard GPIO).

For AF10:-   OTG_FS_SOF

For AF11: – (Not defined, behaves as standard GPIO).

For AF12: – (Not defined, behaves as standard GPIO).

For AF13: – (Not defined, behaves as standard GPIO).

For AF14: – (Not defined, behaves as standard GPIO).

For AF15:-  EVENT OUT

 

Alternate function mapping
Figure 2. Alternate Function Mapping

 

In the following article, let’s see Enabling and disabling GPIO peripheral clock.

 

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