如何正确初始化I2C stm32？
我想从 ADXL345 加速度计获取数据，但似乎我错误地连接了它。
SCL- PC6（带 10k 电阻）
SDA- PC7（带 10k 电阻）
SDO- GND
CS - VCC
GND - GND
3.3v - VCC
这是我的初始化代码：
void I2CG_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
I2C_InitTypeDef I2C_InitStructure;
RCC_AHBPeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
RCC_AHBPeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
// I2CG clock enable
RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2CG, ENABLE);
RCC_AHBPeriphClockCmd(RCC_APB1Periph_I2CG, ENABLE);
// GPIOB clock enable
// I2CG SCL and SDA configuration
GPIO_InitStructure.GPIO_Pin = SCL|SDA;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
// Enable I2CG reset state
RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2CG, ENABLE);
// Release I2CG from reset state
RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2CG, DISABLE);
I2C_DeInit(I2C1);
I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_16_9;
I2C_InitStructure.I2C_OwnAddress1 = 1;
I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
I2C_InitStructure.I2C_ClockSpeed = ClockSpeed;
I2C_Init(I2CG, &I2C_InitStructure);
I2C_Cmd(I2CG, ENABLE);
I2C_AcknowledgeConfig(I2CG, ENABLE);
}
在一个示例中我看到了
GPIO_PinAFConfig(GPIOC,SCLSource,GPIO_AF_I2CG);
GPIO_PinAFConfig(GPIOC,SDASource,GPIO_AF_I2CG);
但我没有可用的 API 。
请帮我。我尝试了很多解决方案，也尝试通过SPI连接，但没有成功:( 请帮忙解决I2C问题。
I want to get data from ADXL345 accelerometer,but seems that I incorrectly connect it.
SCL- PC6(with 10k resistor)
SDA- PC7(with 10k resistor)
SDO- GND
CS - VCC
GND - GND
3.3v - VCC
Here is my code to initalize:
void I2CG_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
I2C_InitTypeDef I2C_InitStructure;
RCC_AHBPeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
RCC_AHBPeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
// I2CG clock enable
RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2CG, ENABLE);
RCC_AHBPeriphClockCmd(RCC_APB1Periph_I2CG, ENABLE);
// GPIOB clock enable
// I2CG SCL and SDA configuration
GPIO_InitStructure.GPIO_Pin = SCL|SDA;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
// Enable I2CG reset state
RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2CG, ENABLE);
// Release I2CG from reset state
RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2CG, DISABLE);
I2C_DeInit(I2C1);
I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_16_9;
I2C_InitStructure.I2C_OwnAddress1 = 1;
I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
I2C_InitStructure.I2C_ClockSpeed = ClockSpeed;
I2C_Init(I2CG, &I2C_InitStructure);
I2C_Cmd(I2CG, ENABLE);
I2C_AcknowledgeConfig(I2CG, ENABLE);
}
In one example I saw
GPIO_PinAFConfig(GPIOC,SCLSource,GPIO_AF_I2CG);
GPIO_PinAFConfig(GPIOC,SDASource,GPIO_AF_I2CG);
But I don't have this API available.
Please help me. I tried many solutions and also tried to connect through SPI, but no success :(
Please help with I2C.
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评论（4）
我意识到这是一篇旧文章，但值得指出。您不应该使用 APB 标志来配置 AHB 总线。检查程序员手册 RM0008（假设您使用的是 stm32f10x 设备）以获取适当的设置。
I realise this is an old post but it's worth pointing out. You shouldn't be using APB flags to configure the AHB bus. Check the programmers manual RM0008 (assuming you're using a stm32f10x device) for the appropriate settings.
SCL和SDA应直接连接。您应该像此方案一样使用上拉电阻： http://en.wikipedia.org /wiki/File:I2C.svg
你的初始化代码看起来没问题，所以也许硬件接线是错误的？
SCL and SDA should be connected directly. You should use pull-up resistors like on this scheme: http://en.wikipedia.org/wiki/File:I2C.svg
Your initialization code looks ok, so maybe hardware wiring is wrong?
我和你有同样的问题。已生成启动条件，但 I2Cx_SR1.SB 位未置位。
我认为我必须启用 I2C 备用功能，但我也必须禁用引脚中的所有其他功能。
就我而言，这是 UART3 功能与 I2C 冲突。
I had the same problem as you. The start condition was generated but the I2Cx_SR1.SB bit doesn't get set.
I thought that I had to enable the I2C alternate function, but I had to disable all the other functions in the pin too.
In my case it was UART3 function conflicting with I2C.
这里有一个声称已经使 I2C 工作的人提供的 STM32 示例代码和应用说明：
http://www .stm32challenge.com/node/143
在尝试未知的加速度计之前，也许可以尝试让串行 EEPROM 等已知的东西正常工作。一旦确定微控制器端正常工作，您就可以连接加速度计并看看会得到什么。
There's sample code and app notes for the STM32 by someone who claims to have gotten I2C working here:
http://www.stm32challenge.com/node/143
Maybe try to get something known like a serial EEPROM working before you try the unknown accelerometer. Once you are sure the microcontroller end works you can connect the accelerometer and see what you get.