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STM32F103 I2C Busy flag

Question asked by Manuel Forcen Munoz on May 22, 2018

Hi to all.

I'm trying to use I2C peripheral of STM32F103C8T6. I'm using a BluePill board. First of all, I know that this problem was published in other forums and so, but after trying other solutions, I didn't find the way to make it work.

I'm using the last STM32CubeMX firmware 1.6.1 V for STM32F103C8Tx.

I tried to make an example that uses I2C in order to make a library for an SSD1306 I2C display.

The example consists of this:


  while (1)
    HAL_GPIO_TogglePin(GPIOC, 1<<13);
      uint8_t buf = 0;
    volatile HAL_StatusTypeDef status;
    status = HAL_I2C_Master_Transmit(&hi2c1, 0x3c<<1, &buf,1, 100);
    HAL_I2C_IsDeviceReady(&hi2c1, 0x3c<<1, 100,200);
    status = HAL_I2C_Master_Transmit(&hi2c1, 0x3c<<1, &buf,1,100);

Here, I call HAL_I2C_Master_Transmit function while the device is connected to the display, just in order to see the wave in a logic analyzer and in the debugger, but the fact is that no wave is shown.

Just to make sure the program was running, I launched the debugger and I read the status variable. With this, I saw that the function is returning HAL_BUSY. It happens to me almost every time I use the I2C peripheral.

I did my research, and I know about the errata thing, so I tried to implement some solutions I found on the Internet in order to clear the BUSY flag.

Please find attached my code.

I'm still learning this amazing microcontroller, so it may be a "basic" thing.

Thanks in advance.


EDIT: Well, this is very strange, but right now it started to work properly. If anyone knows a possible reason, a reply would be appreciated, because it can happen another time.