This document provides an overview of GPIO and interrupt functionality on the STM32F407 microcontroller. It describes how to configure GPIO pins for input, output, and alternate functions. It explains how to set the pin speed, mode, type, and pull-up/pull-down resistors. The document also covers interrupt handling, including the nested vector interrupt controller (NVIC) and external interrupt controller (EXTI). Code examples are provided for setting up GPIO pins and configuring interrupts.

1. 超威猛應⽤用輔具特⼯工隊!
STM32F407 硬體週邊介
紹
⺩王尹⾠辰(JackABK)
2014/09/04
abkabkabkyes@gmail.com

2. GPIO

3. GPIO(General Purpose
Input/Output)
• GPIO is a generic pin on a chip whose
behavior !
including whether it is an input or output pin)
can be controlled (programmed) by the user
at run time.

4. GPIO Input
• Floating
unknown voltage input stage
• Pull-up
connect to high voltage
• Pull-down
connected to ground

5. Input configuration

6. GPIO Output
• push pull
pull-up
pull-down
• open-drain
pull-up
pull-downPull-down

7. Output configuration

8. Setting GPIO pins
• You can configure on the corresponding peripheral:
Speed
Mode
Type
Pull up/pull down resistors

9. Setting GPIO pins
• On the STM32F4xx the GPIO ports are connected
to the AHB1 bus
• Enabling the clock:

10. Setting GPIO pins
• The GPIO’s clock can be anything of the following:
• GPIO_Speed_2MHz
GPIO_Speed_25MHz
GPIO_Speed_50MHz
GPIO_Speed_100MHz

11. Setting GPIO pins
• On the STM32F4 the GPIO can have up to 4 modes
GPIO_Mode_OUT for digital output
GPIO_Mode_IN for digital input
GPIO_Mode_AN for analog input
GPIO_Mode_AF for the alternate functions (like
SPI, I²C, USART, …)

12. Setting GPIO pins
• For the gpio output, The type indicates the
hardware configuration of the pin which can be:
GPIO_OType_PP, !
• a push-pull is driving the output
GPIO_OType_OD!
• the output is open-drain

13. Setting GPIO pins
•Next we can configure pull up, pull down
resistors or nothing at all for each pin:!
•GPIO_PuPd_NOPULL
no resistor connected
•GPIO_PuPd_UP
pin is connected to a pull up resistor
•GPIO_PuPd_DOWN
pin is connect to a pull down resistor

14. Setting GPIO pins
The resistors value of Pull-up and Pull-down

15. Setting GPIO pins
•A complete of code to set the gpio
pin:

16. Interrupt

17. Interrupt Structure

18. Interrupt Structure

19. Interrupt handler
• On way to achieve this goal consists in the creation of
tasks waiting for an interrupt to occur with a semaphore.
!
• Let this safer portion of code actually handle the interrupt.
An ISR “gives” a semaphore and unblock a ’Handler”
task that is able to handler the ISR, making the ISR
execution much shorter

20. Nested Vectored Interrupt
Controller (NVIC)
• Depending on the implementation used by the
silicon manufacturer.
• The NVIC can support up to 240 external
interrupts with up to 256 different priority levels(0
to 255) that can be dynamically reprioritized.
PreemptionPriority: 4bits
SubPriority: 4bits

21. External Interrupt(EXTI)
•Before settings EXTI, You must be:
connected from GPIO
settings EXTI
設定哪條Line
• Interrupt mode
• interrupt condition?(Rising, Falling, Rising&falling )
• LineCmd( ENABLE is open，DISABLE is close.)
settings NVIC
• IRQ_Channel
• PreemptionPriority and SubPriority
• ChannelCmd

22. External Interrupt(EXTI)

23. External Interrupt(EXTI)
The hardware of controller EXTI
(blue boxes are registers, red dots are input pins)

24. External Interrupt(EXTI)
for example

25. Ref.
!
• STM32F4 GPIO Configuration
• NCKU wiki
• Interrupts & ports

26. Thanks!