如何解决未发生具有使用I2C启动条件的DMA的STM32L011K4
我正在尝试使用STM32L011K4的DMA控制器通过I2C与从设备进行通信。目前,我没有从设备,只是想让微控制器将启动条件发送到I2C总线上,但这没有发生。
当我通过STM32CubeIDE在调试模式下运行此代码时,我注意到启动位已设置,但是即使参考手册说一旦发生启动条件就应由硬件将其清除,它也不会清除(I2C_CR2的第656页)。
在示波器上监视SDA和SCL线也表明它们是逻辑1。注意:我在面包板上使用NUCLEO-L011K4,因此IO引脚通过1k电阻连接至Vref。当代码卡住发送开始条件时,所有配置寄存器似乎都包含所需的值,因此我不认为它们会被随机的代码行所破坏。
我不确定是什么原因阻止了启动条件的发送,因此任何帮助将不胜感激。
STM32L011K4参考手册:https://www.st.com/resource/en/reference_manual/dm00108282-ultralowpower-stm32l0x1-advanced-armbased-32bit-mcus-stmicroelectronics.pdf
初始化代码:
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;
}
解决方法
根据参考手册(第604页)
您需要取消注释I2C1->CR2 |= ((uint8_t) (SlaveAddress << 1));
和注释I2C1->TXDR |= ((uint8_t) (SlaveAddress << 1));
来设置从站地址,并且需要设置要传输的字节数。
我看不到您对GPIO的初始化。检查GPIO设置是否正确(替代功能和漏极开路模式)。
也在参考手册中写成
PE必须至少在3个APB时钟周期内保持低电平,以便执行该软件 重启。这可以通过编写以下软件序列来确保:-写入PE = 0-检查 PE = 0-写PE = 1。
我认为您应该尝试这样做。
我还建议使用4.7k电阻上拉至VDD。
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。