USB CDC Power request

[PMath.4]

Does the STM USB CDC driver support power negotiation? If so please could someone point me to where I configure a request for more than the default 100mA.

I'm using STM32F407 and CDC is working nicely but the computer only shows that 100mA is requested. I need more than this to power peripherals which will be attached to the uP.

Any help appreciated

[waclawek.jan · Accepted solution]

USB devices request current through the bMaxPower field in the standard Configuration descriptor, so simply change it there.

JW

[Peter Mather]

Thanks - took a bit of time to find as the field name misses the "b"

from usbd_cdc.c

__ALIGN_BEGIN uint8_t USBD_CDC_OtherSpeedCfgDesc[USB_CDC_CONFIG_DESC_SIZ] __ALIGN_END =
{
  0x09,   /* bLength: Configuation Descriptor size */
  USB_DESC_TYPE_OTHER_SPEED_CONFIGURATION,
  USB_CDC_CONFIG_DESC_SIZ,
  0x00,
  0x02,   /* bNumInterfaces: 2 interfaces */
  0x01,   /* bConfigurationValue: */
  0x04,   /* iConfiguration: */
  0xC0,   /* bmAttributes: */
  250,   /* MaxPower 500 mA */