AN4088 datasheet(47/71 Pages) STMICROELECTRONICS

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AN4088

Firmware migration using the library

functions for different device packages; for example, the USART2_RX pin can be

mapped on PA3 or PA15 pin.

Configuration procedure:

–

Connect the pin to the desired peripherals' Alternate Function (AF) using

GPIO_PinAFConfig() function

–

Use GPIO_Init() function to configure the I/O pin:

- Configure the desired pin in alternate function mode using

GPIO_InitStructure->GPIO_Mode = GPIO_Mode_AF;

- Select the type, pull-up/pull-down and output speed via

GPIO_PuPd, GPIO_OType and GPIO_Speed members

The example below shows how to remap USART2 Tx/Rx I/Os on PD5/PD6 pins in

STM32F1 series:

/* Enable APB2 interface clock for GPIOD and AFIO (AFIO peripheral is used

to configure the I/Os software remapping) */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD | RCC_APB2Periph_AFIO,

ENABLE);

/* Enable USART2 I/Os software remapping

[(USART2_Tx,USART2_Rx):(PD5,PD6)] */

GPIO_PinRemapConfig(GPIO_Remap_USART2, ENABLE);

/* Configure USART2_Tx as alternate function push-pull */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOD, &GPIO_InitStructure);

/* Configure USART2_Rx as input floating */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOD, &GPIO_InitStructure);

In STM32F0 series, you have to update this code as follows:

/* Enable GPIOA's AHB interface clock */

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

/* Select USART2 I/Os mapping on PA14/15 pins

[(USART2_TX,USART2_RX):(PA.14,PA.15)] */

/* Connect PA14 to USART2_Tx */

GPIO_PinAFConfig(GPIOA, GPIO_PinSource14, GPIO_AF_2);

/* Connect PA15 to USART2_Rx*/

GPIO_PinAFConfig(GPIOA, GPIO_PinSource15, GPIO_AF_2);

/* Configure USART2_Tx and USART2_Rx as alternate function */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14 | GPIO_Pin_15;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

AN4088 Datasheet(PDF) 47 Page - STMicroelectronics

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