I2C 在内存读取时返回忙或错误

Question

我开始使用以下代码来处理 Bosch BME280 sensor 使用 Nucleo-F446ZE 和 Nucleo-F411RE 板的

with STM32.Device; use STM32.Device;
with STM32.GPIO; use STM32.GPIO;
with STM32; use STM32;
with STM32.I2C;

with HAL.I2C; use HAL.I2C;
use HAL;

procedure Simple_I2C_Demo is

   --  I2C Bus selected
   Selected_I2C_Port      : constant access STM32.I2C.I2C_Port := I2C_1'Access;
   Selected_I2C_Port_AF   : constant GPIO_Alternate_Function := GPIO_AF_I2C1_4;
   Selected_I2C_Clock_Pin : GPIO_Point renames PB8;
   Selected_I2C_Data_Pin  : GPIO_Point renames PB9;

   Port : constant HAL.I2C.Any_I2C_Port := Selected_I2C_Port;

   --  Shift one because of 7-bit addressing
   I2C_Address : constant HAL.I2C.I2C_Address := 16#76# * 2;


   procedure SetupHardware is
      GPIO_Conf_AF : GPIO_Port_Configuration (Mode_AF);
      Selected_Clock_Speed : constant := 10_000;
   begin
      Enable_Clock (Selected_I2C_Clock_Pin);
      Enable_Clock (Selected_I2C_Data_Pin);

      Enable_Clock (Selected_I2C_Port.all);

      STM32.Device.Reset (Selected_I2C_Port.all);

      Configure_Alternate_Function (Selected_I2C_Clock_Pin, Selected_I2C_Port_AF);
      Configure_Alternate_Function (Selected_I2C_Data_Pin, Selected_I2C_Port_AF);

      GPIO_Conf_AF.AF_Speed       := Speed_100MHz;
      GPIO_Conf_AF.AF_Output_Type := Open_Drain;
      GPIO_Conf_AF.Resistors   := Pull_Up;
      Configure_IO (Selected_I2C_Clock_Pin, GPIO_Conf_AF);
      Configure_IO (Selected_I2C_Data_Pin, GPIO_Conf_AF);

      STM32.I2C.Configure
        (Selected_I2C_Port.all,
         (Clock_Speed          => Selected_Clock_Speed,
          Addressing_Mode      => STM32.I2C.Addressing_Mode_7bit,
          Own_Address          => 16#00#, others => <>));

      STM32.I2C.Set_State (Selected_I2C_Port.all, Enabled => True);
   end SetupHardware;

   ID : HAL.I2C.I2C_Data (1 .. 1);
   Status : HAL.I2C.I2C_Status;

begin

   SetupHardware;

   HAL.I2C.Mem_Read (This          => Port.all,
                 Addr          => I2C_Address,
                 Mem_Addr      => 16#D0#,
                 Mem_Addr_Size => HAL.I2C.Memory_Size_8b,
                 Data          => ID,
                 Status        => Status,
                 Timeout => 15000);

   if Status /= Ok then
      raise Program_Error with "I2C read error:" & Status'Img;
   end if;
end Simple_I2C_Demo;

在这个简单的例子中，我总是在阅读结束时得到一个错误状态。在更完整的代码的上下文中，我总是在等待 15 秒后得到忙状态。

我真的不明白发生了什么，因为我的代码很大程度上受到了 the code I found on Github I2C 传感器的启发。

也许我忘记了 I2C init 的具体代码，但由于我不是专家，所以我更愿意向专家请教:)

Answer 1

不，在 HAL_I2C_Mem_Read 和 HAL_I2C_Master_Transmit、wait、HAL_I2C_Master_Receive 过程之间只是一个细微差别 cf 。如果您知道要接收的数据大小，可以使用 HAL_I2C_Master_Transmit、等等、HAL_I2C_Master_Receive 过程。

C++ HAL I2C 示例在 https://letanphuc.net/2017/05/stm32f0-i2c-tutorial-7/

//Trigger Temperature measurement 
buffer[0]=0x00;  
HAL_I2C_Master_Transmit(&hi2c1,0x40<<1,buffer,1,100);  
HAL_Delay(20);  
HAL_I2C_Master_Receive(&hi2c1,0x40<<1,buffer,2,100);  
//buffer[0] : MSB data 
//buffer[1] : LSB data 
rawT = buffer[0]<<8 | buffer[1]; //combine 2 8-bit into 1 16bit  
Temperature = ((float)rawT/65536)*165.0 -40.0;  
//Trigger Humidity measurement buffer[0]=0x01; 
HAL_I2C_Master_Transmit(&hi2c1,0x40<<1,buffer,1,100);  
HAL_Delay(20);  
HAL_I2C_Master_Receive(&hi2c1,0x40<<1,buffer,2,100);  
//buffer[0] : MSB data 
//buffer[1] : LSB data 
rawH = buffer[0]<<8 | buffer[1]; //combine 2 8-bit into 1 16bit  
Humidity = ((float)rawH/65536)*100.0; HAL_Delay(100); }

注意它使用HAL_I2C_Master_Transmit，等待20ms直到slave把数据放到总线上，然后用HAL_I2C_Master_Receive接收。此代码有效，我自己测试过。

可能的问题是 BME280 支持单字节读取和多字节读取（直到它发送 NOACK 并停止） . HAL_I2C_Mem_Read 等待 ACK 或停止但由于某些原因它没有得到它导致 Busy 然后 Timeout 行为的原因，cf数据表第 33 页 http://www.embeddedadventures.com/datasheets/BME280.pdf 用于多字节读取。您将超时指定为 15 秒，并在 15 秒后获得超时。 所以看起来 BME280 根本没有停止发送，或者它什么也没发送，包括不发送 NOACK 和停止条件 ...

HAL_I2C_Mem_Read有时候会出问题，这个要看slave https://community.arm.com/developer/ip-products/system/f/embedded-forum/7989/trouble-getting-values-with-i2c-using-hal_library

顺便说一下

HAL.I2C.Mem_Read (This          => Port.all,
                 Addr          => I2C_Address,
                 Mem_Addr      => 16#D0#,
                 Mem_Addr_Size => HAL.I2C.Memory_Size_8b,
                 Data          => ID,
                 Status        => Status,
                 Timeout => 15000);

你尝试从寄存器中读取 1 个字节的芯片标识号 D0 cf http://www.embeddedadventures.com/datasheets/BME280.pdf 第 26 页

Answer 2

终于找到问题所在了。在使用STM HAL用C测试并调查Ada配置代码后，我发现缺少一行：

      GPIO_Conf_AF.AF_Speed       := Speed_100MHz;
      GPIO_Conf_AF.AF_Output_Type := Open_Drain;
      GPIO_Conf_AF.Resistors   := Pull_Up;

      -- Missing configuration part of the record
      GPIO_Conf_AF.AF := Selected_I2C_Port_AF;
      -- That should be present even though there was a call to configure
      -- each pin few lines above

      Configure_IO (Selected_I2C_Clock_Pin, GPIO_Conf_AF);
      Configure_IO (Selected_I2C_Data_Pin, GPIO_Conf_AF);

在Configure_Alternate_Function之后使用Configure_IO破坏了配置，因为有一部分记录未初始化，GPIO 配置不正确。

更准确地说，在查看 GPIO 处理内部的代码后，Configure_IO 调用 Configure_Alternate_Function 使用 GPIO_Port_Configuration 记录的 AF 部分。就我而言，它正在重置它。

由于缺少行，代码现在可以使用 Mem_Read 和 Master_Transmit/[= 正确运行22=]Master_Receive.

非常感谢 ralf htp 建议我深入研究生成的 C 代码。

I2C 在内存读取时返回忙或错误

I2C returning Busy or Error on memory reading

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stm32

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