STM32L011K4 帶有 DMA 使用 I2C 啟動條件未發生

Question

我正在嘗試使用 STM32L011K4 的 DMA 控制器通過 I2C 與從設備進行通信。 目前，我沒有從設備，只是試圖讓微控制器將啟動條件發送到 I2C 總線上，但這並沒有發生。

當我通過 STM32CubeIDE 在調試模式下運行此代碼時，我注意到啟動位已設置，但它永遠不會清除，即使參考手冊說一旦啟動條件發生它應該由硬件清除（I2C_CR2 的第 656 頁）。

在我的示波器上監測 SDA 和 SCL 線也表明它們是邏輯 1。 注意：我在面包板上使用 NUCLEO-L011K4，所以 IO 引腳通過 1k 電阻連接到 Vref。 當代碼在發送開始條件時被卡住時，所有配置寄存器似乎都包含所需的值，所以我不相信它們會被隨機的代碼行破壞。

我不確定是什么阻止了開始條件的發送，因此我們將不勝感激。

STM32L011K4 數據表： https ://www.st.com/content/ccc/resource/technical/document/datasheet/42/c0/ab/e5/71/7a/47/0b/DM00206508.pdf/files/DM00206508.pdf /jcr:content/translations/en.DM00206508.pdf

STM32L011K4 參考手冊： https ://www.st.com/resource/en/reference_manual/dm00108282-ultralowpower-stm32l0x1-advanced-armbased-32bit-mcus-stmicroelectronics.pdf

初始化代碼：

void Init_I2C1_DMA() {
    /*  Basic I2C Initialization for 100 kHz I2C, 24 MHz SYSCLK, /1 APB1 scaler  */
    RCC->APB1ENR |= RCC_APB1ENR_I2C1EN; // Enable peripheral clock for I2C1

    I2C1->CR1 &= ~(I2C_CR1_PE);         // Disable I2C1
    I2C1->CR1 = 0;                      // Reset CR1

    I2C1->TIMINGR = 0;                  // Reset timer settings
    /* APB1 clock (I2C1 clock) is set in RCC_CFGR reg -- keep at divide by 1 -- 24 MHz SYSCLK
     * Refer to table 103 for timing value source.  t_presc was found to be 250 ns for 100 kHz I2C, so PRESC was set to match that for SYSCLK = 24 MHz
     * All subsequent settings are copied from table 103 from STM32L011K4 reference manual
     */
    I2C1->TIMINGR |= (0x5 << 28)|(0x4 << 20)|(0x2 << 16)|(0x0F << 8)|(0x13 << 0);

    /* Desired settings:
     * RXDMAEN enable, ANF enable.
     */
    I2C1->CR1 |= (0x8 << I2C_CR1_DNF_Pos)|I2C_CR1_ERRIE;
    I2C1->CR2 = 0;                      // Reset contents (ACKs are enabled by default)
    NVIC_EnableIRQ(I2C1_IRQn);
    NVIC_SetPriority(I2C1_IRQn, 0);

    /* DMA initialization */

    /* Since this is peripheral to memory, we use I2C1_RX, which is available on DMA channels 3,7.  We used channel 3, but 7 would work the same. */
    RCC->AHBENR |= RCC_AHBENR_DMA1EN;                           // Enable peripheral clock for DMA1
    DMA1_Channel3->CCR &= ~(0x00000001);                        // Disable Channel 3 DMA

    // Configure DMA channel mapping
    DMA1_CSELR->CSELR &= ~0x00000F00; // Channel 3 re-mapping mask
    DMA1_CSELR->CSELR |=  0x00000600; // Channel 3 re-mapped to I2C1_RX

    /* Configure NVIC for DMA */
    NVIC_EnableIRQ(DMA1_Channel2_3_IRQn);
    NVIC_SetPriority(DMA1_Channel2_3_IRQn, 0);

    return;
}

void I2C1_DMA_Start_Read(uint8_t SlaveAddress, uint8_t RegisterAddress, int* MemoryBaseAddress, int BufferSize) {
    // We need to put the device address out on the serial line before we can hand it over to the DMA

    I2C1->CR1 &= ~(I2C_CR1_PE);                                 // Disable I2C1
    DMA1_Channel3->CCR &= ~DMA_CCR_EN;                          // Disable Channel 3 DMA

    DMA1_Channel3->CCR &= ~(0x00007FFF);                        // Channel 3 DMA mask
    // Configure DMA Channel 3 for 16 bit memory and peripheral, and other aliased settings (reference manual page 249, 10.4.3)
    DMA1_Channel3->CCR |=  (0b01 << 10)|(0b01 << 8)|DMA_CCR_MINC|DMA_CCR_TEIE|DMA_CCR_TCIE;

    DMA1_Channel3->CPAR =  (uint32_t) RegisterAddress;
    DMA1_Channel3->CMAR =  (uint32_t) MemoryBaseAddress;
    DMA1_Channel3->CNDTR = (uint16_t) BufferSize;

    I2C1->CR1 &= (~I2C_CR1_TXDMAEN);                            // Disable TX DMA for I2C1
    I2C1->CR1 |= I2C_CR1_RXDMAEN;                               // Enable RX DMA for I2C1
    // I2C1->CR2 |= ((uint8_t) (SlaveAddress << 1));            // Set up the slave address for DMA read
    while(!(I2C1->ISR & I2C_ISR_TXE));
    I2C1->TXDR |= ((uint8_t) (SlaveAddress << 1));              // Set up the slave address for DMA read
    I2C1->CR2 |= I2C_CR2_RD_WRN;

    DMA1_Channel3->CCR |= DMA_CCR_EN;                           // Activate DMA channel 3
    I2C1->CR1 |= I2C_CR1_PE;                                    // Enable I2C1

    I2C1->CR2 |= I2C_CR2_START;                                 // Generate start condition
    while(I2C1->CR2 & I2C_CR2_START);                           // Wait until hardware clears the start bit

    // ???

    return;
}

Answer 1

根據參考手冊（第 604 頁），您需要取消注釋I2C1->CR2 |= ((uint8_t) (SlaveAddress << 1)); 並評論I2C1->TXDR |= ((uint8_t) (SlaveAddress << 1)); 設置從機地址，需要設置要傳輸的字節數。

我看不到您對 GPIO 的初始化。 檢查 GPIO 設置是否正確（替代功能和開漏模式）。

同樣在參考手冊中寫了這個

為了執行軟件復位，PE 必須在至少 3 個 APB 時鍾周期內保持低電平。 這是通過寫入以下軟件序列來確保的： - 寫入 PE=0 - 檢查 PE=0 - 寫入 PE=1。

我認為你應該嘗試這樣做。

另外我建議使用 4.7k 電阻來拉到 VDD。