USB OTG low level driver UM1021
20/107 Doc ID 18153 Rev 3
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.
Internal DMA use in High speed mode
The USB OTG High Speed core embeds an internal DMA capable of handling the FIFO I/O
request automatically without using the CPU. However the data structures used in DMA
mode should be 32-bit aligned.
The internal DMA feature is selected by enabling the
USB_OTG_HS_INTERNAL_DMA_ENABLED define in the usb_conf.h file.
Note: The Internal DMA and Specific OUT and IN interrupt features can be used together to
enhance data transfer performance.
5.4.5 Programming host drivers
Host driver initialization
The host is initialized using the following function:
HCD_Init (USB_OTG_CORE_HANDLE *pdev, USB_OTG_CORE_ID_TypeDef coreID)
This function sets the Rx and periodic/non periodic Tx FIFOs size and start address. The
user can change the FIFO settings by modifying the default values and changing the FIFO
depth for each periodic and non periodic Tx FIFO in the usb_conf.h file.
Host channel initialization
Once the USB OTG core is initialized, the host mode is selected. The upper layer may call
the low level driver to open or close a host channel to start transferring data. The following
API is used:
uint32_t HCD_HC_Init (USB_OTG_CORE_HANDLE *pdev, uint8_t hc_num)
Host driver structures
After initializing the Host driver (HCD), the low level driver holds several structures and
buffers for data and URB status monitoring. The host channel structures are kept in the host
driver and accessed from the upper layer through the host number index.
typedef struct _HCD
{
uint8_t Rx_Buffer [MAX_DATA_LENGTH];
__IO uint32_t ConnSts;
__IO uint32_t ErrCnt[USB_OTG_MAX_TX_FIFOS];
__IO uint32_t XferCnt[USB_OTG_MAX_TX_FIFOS];
__IO HC_STATUS HC_Status[USB_OTG_MAX_TX_FIFOS];
__IO URB_STATE URB_State[USB_OTG_MAX_TX_FIFOS];
USB_OTG_HC hc [USB_OTG_MAX_TX_FIFOS];
uint16_t channel [USB_OTG_MAX_TX_FIFOS];
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