AN3427 datasheet(45/52 Pages) STMICROELECTRONICS

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AN3427

Firmware migration using the library

Doc ID 019001 Rev 1

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GPIO_PinAFConfig(GPIOD, GPIO_PinSource5, GPIO_AF_USART2);

/* Connect PD6 to USART2_Rx*/

GPIO_PinAFConfig(GPIOD, GPIO_PinSource6, GPIO_AF_USART2);

/* Configure USART2_Tx and USART2_Rx as alternate function */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_Init(GPIOD, &GPIO_InitStructure);

Note:

When the I/O speed is configured in 50 MHz or 100 MHz mode, it is recommended to use

the compensation cell for slew rate control to reduce the I/O noise on the power supply.

4.5

EXTI

The example below shows how to configure the PA0 pin to be used as EXTI Line0 in STM32

F1 series:

/* Enable APB interface clock for GPIOA and AFIO */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

/* Configure PA0 pin in input mode */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Connect EXTI Line0 to PA0 pin */

GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);

/* Configure EXTI line0 */

EXTI_InitStructure.EXTI_Line = EXTI_Line0;

EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

EXTI_InitStructure.EXTI_LineCmd = ENABLE;

EXTI_Init(&EXTI_InitStructure);

In F2 series the configuration of the EXTI line source pin is performed in the SYSCFG

peripheral (instead of AFIO in F1 series). As result, the source code should be updated as

follows:

/* Enable GPIOA's AHB interface clock */

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

/* Enable SYSCFG's APB interface clock */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

/* Configure PA0 pin in input mode */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Connect EXTI Line0 to PA0 pin */

SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);

/* Configure EXTI line0 */

EXTI_InitStructure.EXTI_Line = EXTI_Line0;

EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

EXTI_InitStructure.EXTI_LineCmd = ENABLE;

EXTI_Init(&EXTI_InitStructure);

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