UM1021 USB OTG low level driver
Doc ID 18153 Rev 2 19/107
USB data transfer flow
The DCD layer offers the user all APIs needed to start and control a transfer flow using the
following set of functions:
uint32_t DCD_EP_PrepareRx ( USB_OTG_CORE_HANDLE *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint16_t buf_len);
uint32_t DCD_EP_Tx (USB_OTG_CORE_HANDLE *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint32_t buf_len);
uint32_t DCD_EP_Stall (USB_OTG_CORE_HANDLE *pdev,
uint8_t epnum);
uint32_t DCD_EP_ClrStall (USB_OTG_CORE_HANDLE *pdev,
uint8_t epnum);
uint32_t DCD_EP_Flush (USB_OTG_CORE_HANDLE *pdev,
uint8_t epnum);
The DCD layer of the USB OTG Low Level Driver has one function that must be called by
the USB interrupt (high speed or full speed):
uint32_t DCD_Handle_ISR (USB_OTG_CORE_HANDLE *pdev)
The dcd_int.h file contains the function prototypes of the functions called from the library
core layer to handle the USB events.
USB driver structure definition
typedef struct _USBD_DCD_INT
{
uint8_t (* DataOutStage) (USB_OTG_CORE_HANDLE *pdev , uint8_t epnum);
uint8_t (* DataInStage) (USB_OTG_CORE_HANDLE *pdev , uint8_t epnum);
uint8_t (* SetupStage) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* SOF) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* Reset) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* Suspend) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* Resume) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* IsoINIncomplete) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* IsoOUTIncomplete) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* DevConnected) (USB_OTG_CORE_HANDLE *pdev);
uint8_t (* DevDisconnected) (USB_OTG_CORE_HANDLE *pdev);
}USBD_DCD_INT_cb_TypeDef;
In the library layer, once the USBD_DCD_INT_cb_TypeDef structure is defined, it should be
assigned to the USBD_DCD_INT_fops pointer.
Example:
USBD_DCD_INT_cb_TypeDef *USBD_DCD_INT_fops = &USBD_DCD_INT_cb;
Specific OUT and IN interrupt
The USB OTG High Speed core embeds two independent interrupts for endpoint 1 IN and
endpoint 1 OUT. Consequently, the USBD_OTG_EP1OUT_ISR_Handler and
USBD_OTG_EP1IN_ISR_Handler can be used to lighten the global USB OTG interrupt.
The specific endpoint feature is selected by enabling the
USB_OTG_HS_DEDICATED_EP1_ENABLED define in the usb_conf.h file.
