Asst. Prof. Dr. Alper ŞİŞMAN Practice 2 Asst. Prof. Dr. Alper ŞİŞMAN

GPIO Module Output states: push-pull or open drain + pull-up/down Output data from output data register (GPIOx_ODR) or peripheral (alternate function output) Speed selection for each I/O Input states: floating, pull-up/down, analog Input data to input data register (GPIOx_IDR) or peripheral (alternate function input) Bit set and reset register (GPIOx_BSRR) for bitwise write access to GPIOx_ODR

Locking mechanism (GPIOx_LCKR) provided to freeze the I/O configuration Analog function Alternate function input/output selection registers (at most 16 AFs per I/O) Fast toggle capable of changing every two clock cycles Highly flexible pin multiplexing allows the use of I/O pins as GPIOs or as one of several peripheral functions During and just after reset, the alternate functions are not active and the I/O ports are configured in input floating mode.

The configuration steps of GPIO pin The clock signal of corresponding GPIO HW must be activated: RCC->AHB1ENR: Reset&Clock control reg.->AHB1 enable register. The pins must be defined as input or output GPIOD->MODER: Mode register 32-bit for 16 pins:

The output type must be configured GPIOD=>OTYPER: The output speed must be configured GPIOD=>OSPEEDR: 32 bit register for 16 pins.

The pull up resistor configuration mus be set GPIOD=>PUPDR: 32 bit reg.16 pins

Read/Write Registers GPIO port input data register: GPIOD=>IDR GPIO port output data reg.:GPIOD=>ODR GPIO port bit set/reset reg.: GPIOD=>BSRR

Other GPIO Registers GPIO port configuration lock reg. GPIO alternate function low reg. GPIO alternate function high reg. Further information can be seen on page 278. (ref manual RM0090)

Blinking LED #include "STM32F4xx.h” void SystemInit() { Run in DEBUG mode step by step and see four LED in on and off. #include "STM32F4xx.h” void SystemInit() { (*((int*)0xE000ED88))|=0x0F00000; // Floating Point donanimini aktiflestir. RCC->AHB1ENR |= 0x00000008; // GPIOD donaniminin clock sinyalini uygulayalim GPIOD->MODER = 0x55000000; // GPIOD nin 15, 14, 13, 12 pinleri cikis tanimlandi (Ledler bu pinlerde) GPIOD->OSPEEDR= 0xFFFFFFFF; // GPIOD nin tum cikislari en yuksek hizda kullanacagiz }

int main() { while(1) GPIOD->ODR= 0x0000F000; // Ledler yansin GPIOD->ODR= 0x00000000; // Ledler sonsun }

Add a delay subrotine void delayy(){ int delay0 = 0x000FFFFF; while (delay0--){ }

Call delayy from main int main() { while(1) GPIOD->ODR= 0x0000F000; // Ledler yansin delayy(); GPIOD->ODR= 0x00000000; // Ledler sonsun }

Read Button Activate GPIOA clock Configure A0 as input (it is default), bus speed and no pull up/down void SystemInit() { (*((int*)0xE000ED88))|=0x0F00000; // Floating Point donanimini aktiflestir. RCC->AHB1ENR |= 0x00000009; // GPIOD &A donaniminin clock sinyalini uygulayalim GPIOD->MODER = 0x55000000; // GPIOD nin 15, 14, 13, 12 pinleri cikis tanimlandi (Ledler bu pinlerde) GPIOD->OSPEEDR= 0xFFFFFFFF; // GPIOD nin tum cikislari en yuksek hizda kullanacagiz GPIOA->OSPEEDR= 0xFFFFFFFF; // GPIOA nin tum girisleri en yuksek hizda kullanacagiz GPIOA->PUPDR = 0x00000000; }

Stop blinking When button is pressed the blinking will stop: int main() { while(1) while ((GPIOA->IDR & 0x1) == 0){ } GPIOD->ODR= 0x0000F000; // Ledler yansin delayy(); GPIOD->ODR= 0x00000000; // Ledler sonsun

Define D0 as output&observe it void SystemInit() { (*((int*)0xE000ED88))|=0x0F00000; // Floating Point donanimini aktiflestir. RCC->AHB1ENR |= 0x00000009; // GPIOD &A donaniminin clock sinyalini uygulayalim GPIOD->MODER = 0x55000001; // GPIOD nin 15, 14, 13, 12 ve 0. pinleri cikis tanimlandi (Ledler bu pinlerde+0. pin) GPIOD->OSPEEDR= 0xFFFFFFFF; // GPIOD nin tum cikislari en yuksek hizda kullanacagiz GPIOA->OSPEEDR= 0xFFFFFFFF; // GPIOA nin tum girisleri en yuksek hizda kullanacagiz GPIOA->PUPDR = 0x00000000;}

HW#2 Connect a 7-segment to the STM32F4x board Write a number between 1-9 on the 7-segment When user button is pressed number 0 should be seen on the 7-segment.