Can I configure I2C1 work in full speed mode (400kHz) on STM32F4Discovery board?

[bluenow1896]

Posted on December 23, 2017 at 03:07

I have a STM32F4 Discovery board and I try to using STM32CubeMX to start a initial project.

One issue I have is that I can't select the I2C1 to work on full speed mode, the mode other than standard was grayed out.

As I know the standard mode is quite slow as 100kHz, and even the full speed mode is at 400kHz, not really fast.

The I2C specification defined fast mode with the clock to 1MHz and even high speed on 3.4M. I can't believe that it can't support full speed mode (400kHz) on I2C module on STM32F4Discovery board. What's wrong?

Note: this post was migrated and contained many threaded conversations, some content may be missing.

[bluenow1896]

Posted on December 24, 2017 at 16:45

Your guess is wrong. The CubeMX has no knowledge about custom board, but it does know the board details about Discovery and Nucleo boards. They are all from ST.

Once again, I'm not here to discuss the hardware challenge to promote I2C speed to 400kHz. As I had mentioned, I had successfully to configure and run the I2C module on 1MHz on Nucleo-STM32L476 with attached I2C modules.

The problem I have is, when using CubeMX to configure STM32F4Discovery board, the I2C1 fast mode was grayed out, which left the I2C module can only run at 100kHz.

Is there a legitimate reason for CubeMX doing this? Or just a bug in CubeMX?

-Andy