Not worth it, STM products are garbage.

[bym]

H

[TDK]

Is the LED off if you comment out BSP_ledOn()? Your code only turns the LED on, not off. If it's on to begin with, pressing the button won't do anything.

Need to set port C in EXTI_EXTICRx register.

in the interrupt, you should check for and clear the EXTI flag for pin 13 in EXTI_FPR1, and only turn on the LED if it's set. Don't need to do anything with NVIC functions or register.

[bym]

Thank you TDK, I should've clarified, the interrupt is always on,  when I set a breakpoint at the interrupt, it breaks all the time, hence the LED is always on.

I added code for FPR1 to clear that bit and the LED now blinks very fast that it is barely on, looks like d flicker.

I haven't figured out how to use EXTI_EXTICRx yet. Looks aweful convoluted and will take more time.

Thank you again.

[TDK]

The RM is a little confusing, but I think it's all written correctly.

> I need help with figuring out what x and m are and what exactly is nb_ioport?

For the EXTICR4 register, x=4. m = 4 * (x - 1) per the manual, so m=12 for this register.

nb_ioport is the pin number. It's 13 for PC3.

EXTICR1 configures pins 0-3, EXTICR2 configures pins 4-7, etc, so EXTICR4 configures pins 12-15.

x=4 in EXTICR4, so m = 4 * (x - 1) = 12, so you want to configure the EXTIm+1 register, which is bits 8-15. Write a 0x2 there.

EXTI_EXTICR1_EXTI0_0 is bit 0 of the EXTI_EXTICR1_EXTI0 field, and so on. This is the standard convention with all the CMSIS register defines.

Does that help?

[KnarfB]

This code is for PA8 on a C011:

void EXTI4_15_IRQHandler(void) {
    if(EXTI->FPR1 & EXTI_FPR1_FPIF8) {
        // do something
        EXTI->FPR1 |= EXTI_FPR1_FPIF8; // clear pending bit
    }
}

// make PA8 EXTI interrupt
void init_EXTI() {

    RCC->IOPENR |= RCC_IOPENR_GPIOAEN; // enable peripheral clock
    (void)RCC->IOPENR; // read back to make sure that clock is on
    GPIOA->MODER = (GPIOA->MODER & ~GPIO_MODER_MODE8_Msk) | (0 << GPIO_MODER_MODE8_Pos); // input mode

    EXTI->FTSR1 |= EXTI_FTSR1_FT8; // enable falling edge of Px8 (x=any port), we use it for PA8 
    EXTI->EXTICR[3] |= 0 << EXTI_EXTICR3_EXTI8_Pos;     // set port to A for PA8

    EXTI->IMR1 |= EXTI_IMR1_IM8;    // EXTI CPU wakeup with interrupt mask register
    //EXTI->EMR1 |= EXTI_EMR1_EM8;    // EXTI CPU wakeup with event mask register

    NVIC_EnableIRQ(EXTI4_15_IRQn);
}

What you have found (12.5.6 EXTI external interrupt) plus Table 47. EXTI controller register register map and reset values explains it. Yes, each 8-bit block in a EXTI_EXTICRx is a bitmap of the enableds ports.

hth

KnarfB

[bym]

---

that?

[TDK]

See the highlighted regions. (EXTIm+1 is on the next page, same idea though.)

[KnarfB]

> Doesn't that mean that x1 is for bit 0-7 

No, these are the GPIO port selection bits.