i2c - STM32F030F4 在 Bare Metal 中无法正确启动 I2C1

Question

STM32F030F4 无法正确启动 I2C1。这是我的代码：

//Clocks------------------------------------------------
    RCC->AHBENR  = 0x200000;
    RCC->APB1ENR = 0x4040 ; 
//------------------------------------------------------    

//GPIO-------------------------------------------------- 
//Configure Alternate Fucntion GPIO to I2C1
    GPIOA->AFR[1]  = 0x440  //(0b0100)<<4 | (0b0100)<<8 //AF4;
//Set GPIOA Pin 9-10 as Alternate Function
    GPIOA->MODER   = 0x280000;
//Set GPIOA pin 9-10 as speed as High
    GPIOA->OSPEEDR = 0x3c0000; 
//Set GPIOA pin 9-10 as open drain
    GPIOA->OTYPER  = 0x600;
//Set GPIOA pin 9-10 as no Pull-up Pull-down
    GPIOA->PUPDR   = 0x0;
//------------------------------------------------------

//I2C Resgisters
    I2C1->TIMINGR = 0x00201D2D;
    I2C1->CR1     = 0x1;
    I2C1->CR2           = 0x307001c;
    I2C1->TXDR      = 0x111;        
    //Start I2C 
    I2C1->CR2 |= (0b1) << 13;

但输出不正确。它是这样的：

SDA 端口不工作。

Answer 1

这条线似乎有问题。

GPIOA->AFR[1]  = GPIO_Aternate_Function_I2C1;

如果 I2C 引脚为 9 和 10，您应该设置 AFSEL9 和 AFSEL10 的值。但是您设置 AFSEL8（这是 AFR[1] 中的最低值），并清除其他值。

这段代码应该做的事情：

GPIOA->AFR[1]  = GPIO_Aternate_Function_I2C1 * 0x00000110;

Answer 2

问题解决了..

时钟有问题：更改：（

//Enable PORTA clocks
RCC->AHBENR  |= 0x20000;

//Enable I2C1 clocks
RCC->APB1ENR |= 0x200000 ;

)