AN3427 datasheet(43/52 Pages) STMICROELECTRONICS

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AN3427

Firmware migration using the library

Doc ID 019001 Rev 1

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4.4

GPIO

This section explain how to update the configuration of the different GPIO modes when

moving the application code from STM32 F1 series to F2 series.

4.4.1

Output mode

The example below shows how to configure an I/O in output mode (for example to drive an

LED) in STM32 F1 series:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_xxMHz;/* 2, 10 or 50 MHz */

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;

GPIO_Init(GPIOy, &GPIO_InitStructure);

In F2 series you have to update this code as follows:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; /* Push-pull or open drain */

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; /* None, Pull-up or pull-down */

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_xxMHz; /* 2, 25, 50 or 100 MHz */

GPIO_Init(GPIOy, &GPIO_InitStructure);

4.4.2

Input mode

The example below shows how to configure an I/O in input mode (for example to be used as

an EXTI line) in STM32 F1 series:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOy, &GPIO_InitStructure);

In F2 series you have to update this code as follows:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; /* None, Pull-up or pull-down */

GPIO_Init(GPIOy, &GPIO_InitStructure);

4.4.3

Analog mode

The example below shows how to configure an I/O in analog mode (for example an ADC or

DAC channel) in STM32 F1 series:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;

GPIO_Init(GPIOy, &GPIO_InitStructure);

In F2 series you have to update this code as follows:

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_x ;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOy, &GPIO_InitStructure);

4.4.4

Alternate function mode

In STM32 F1 series

The configuration to use an I/O as alternate function depends on the peripheral mode

used. For example, the USART Tx pin should be configured as alternate function push-

pull while the USART Rx pin should be configured as input floating or input pull-up.

To optimize the number of peripherals available in MCUs that have fewer pins (smaller

package size), it is possible by software to remap some alternate functions to other

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