STM32F105 in USB Device Mode not recognized by PC

[marten2]

Posted on November 30, 2012 at 08:37

Hi,

I am trying to connect an F105 via USB on a PC. But the F105 is only recognized when I put an external 1,5K pullup resistor on the USB D+ dataline. Unfortunately, the same MCU is also used as an USB host for storing data on an USB pen drive. But when I tried this, the pen drive is only recognized, when the 1,5K resistor is removed. My question: how do I activate / deactivate the internal pullup resistors of the F105? Trying to switch the Pull-Up resistor with a GPIO pin is not an option - the hardware design has finished. Thanks for every help! Regards Moardy #connectivity-usb

[Fleck]

Posted on November 30, 2012 at 10:40

STM32F105 has a known issue with pin PA9 and the internal bootloader. Could that be you problem? See STM32F105 Errata document.

If that is not the cause of the problem, look at your software: The ST;32F105 has this pull-up resistor internally, which must be triggered by software when a connection to a USB Host has been detected. We have implemented USB Host/Device switching with the STM32F105, it worked for us.

[marten2]

Posted on November 30, 2012 at 12:36

Hi Jens,

thanks for your reply. >STM32F105 has a known issue with pin PA9 and the internal bootloader. Could that be you >problem? I know this issue very well, but the problem is not during programming, it's during normal work of the application firmware. A>The STF32F105 has this pull-up resistor internally, which must be triggered by software when a connection to a USB Host has been detected. Okay, but is that be done automatically through the UBS-Hardware of the F105 , if you change its mode from host to device and vice versa or is an addional step needed to configure the hardware e.g. switching the resistors on/off ? Regards Marten From: jensPosted: Friday, November 30, 2012 10:40 AMSubject: STM32F105 in USB Device Mode not recognized by PC

STM32F105 has a known issue with pin PA9 and the internal bootloader. Could that be you problem? See STM32F105 Errata document.

If that is not the cause of the problem, look at your software: The ST;32F105 has this pull-up resistor internally, which must be triggered by software when a connection to a USB Host has been detected. We have implemented USB Host/Device switching with the STM32F105, it worked for us.