F107 USB OTG as a device only

[DiBosco]

Posted on May 05, 2016 at 19:13

Folks,

I have code for using the F103's USB device port as a virtual com port. Does anyone know:

1. Could I use that ''as is'' on the F107's OTG port. I only ever want to use it as a device.

2. Do I really have to have  OTG_FS_VBUS connected to the USB connector's 5V line? Sadly, the board's been laid out with PA9 - which is the VBUS connector - as the USART function.

Thanks!

Rob

[slimen]

Posted on May 06, 2016 at 15:39

Hi,

I'd recommend you to have a look to the

http://www2.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf

, paragraph ''13.3.4  PA9 excessive power consumption when USB cable is plugged in bootloader V2.0 :

When connecting a USB cable after booting from System-Memory mode, PA9 pin (connected to VBUS=5 V) is also shared with USART TX pin which is configured as alternate push-pull and forced to 0 since the USART peripheral is not yet clocked. As a consequence, a current higher than 25 mA is drained by PA9 I/O and may affect the I/O pad reliability.

This limitation is fixed in bootloader version 2.1 by configuring PA9 as alternate function push-pull when a correct 0x7F is received on RX pin and the USART is clocked. Otherwise, PA9 is configured as alternate input floating. 

''

Regards

[DiBosco]

Posted on May 09, 2016 at 11:10

Hi,

I'm not worried about the bootloader as we're doing that over USB and Ethernet.

I'm concerned over whether I can use the F103 device code as is with the OTG peripheral and whether it will work if I ignore PA9.

Thanks!

[DiBosco]

Posted on May 12, 2016 at 19:43

Bump!

Has no-one done this? Has no-one used the F107 as a CDC? Do you *have* to invoke the OTG_DEV_Init() for example? Can you just run it exactly as the F103? I've tried the latter, but absolutely no registers in the USB_OTG_DEVICE module are being set. If I try and compile for OTG support I get zillions of errors. I suspect partly because I'm using such old libraries with this very old version of FreeRTOS.

I'm chasing my tail here and would *really* appreciate some advice from someone who has implemented this as a CDC or VCP device - which terminology you prefer.

Most especially, if I don't implement OTG_FS_VBUS

 am I doomed to failure, even if I manage to compile for USB_OTG support?

Many thanks.