Custome board with stm32f427 USB failure

Paul Hamberg · ‎2018-04-23

Posted on April 23, 2018 at 13:28

Hi,

I am developing a custome board with the stm32f427.

I cannot get the USB to connect to the PC. I allways get the number 43 error 'USB device unknown'

The builtin bootloader is loaded and I can see the code running on the MCU. And I can talk to the board via USART.

I use a USB type B as a connection.

Can anyone help me?

Thanks in advance!

waclawek.jan · ‎2018-04-23

Posted on April 24, 2018 at 02:07

Compare the design of your custom board with some known working reference design, e.g. the respective Discovery board.

JW

Paul Hamberg · ‎2018-04-25

Posted on April 25, 2018 at 14:06

Hi JW!

Thankyou for your answer!

The board is based on an original design which is working fine. The only differense is that

I use a USB type B instead for a micro USB

I have noticed when reading the forum that there is some trouble getting the USB interface working on the stm32F427.

Does anyone know if there has been any change to the built in bootloader or the stm32f427 the last three years?

Regards!

Tesla DeLorean · ‎2018-04-25

Posted on April 25, 2018 at 15:01

The F429I-DISCO had issues because the USB-HS port at the South end of the board isn't usable by the System Loader. If you use the USB-FS port it should work on the F427, but as always the System Loader is sensitive to other interface pins transitioning, and having an HSE crystal/clock source that starts rapidly and is one of the supported frequencies.

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Paul Hamberg · ‎2018-05-30

Posted on May 30, 2018 at 10:56

Hi!

The problem is solved!

It was a 'ESD-component' that had a pull upp resistor.

in our first config the speed for communication was set to 1,5Mbit and was making the USB not working.

now we have changed the config of the ESD so the communication speed is 12Mbit and

all is working perfect now!