UM0290 datasheet(11/76 Pages) STMICROELECTRONICS

11 / 76 page

UM0290

STR7/STR9 USB firmware library

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wCount);

bEpNum = endpoint number

bDir

= endpoint direction

wCount = buffer counter

GetEPDblBuf0Count

: u16 GetEPDblBuf0Count(u8 bEpNum);

GetEPDblBuf1Count

: u16 GetEPDblBuf1Count(u8 bEpNum);

bEpNum

= endpoint number

return value : buffer counter

Double buffer STATUS

The simple and double buffer modes use the same functions to manage the

Endpoint STATUS except the STALL status for double buffer mode which is

managed by the function:

SetDouBleBuffEPStall:

void SetDouBleBuffEPStall(u8 bEpNum,u8 bDir)

bEpNum = endpoint number

bDir

= endpoint direction

Direct Memory Access (DMA) functions: (only available for STR91x) For the

STR91x, the data transfer from/to the PMA can be managed using the Direct Memory

Access Controller (DMAC) to decrease the CPU usage. This section describes the

different implemented functions used to manage the two DMA transfer modes (unlinked

and linked).

DMA Unlinked mode functions

In this mode only a single data packet can be transferred by the DMA. Multiple

endpoints can be mapped on the channel (3 in Tx mode and 10 in Rx mode). The

CPU has to configure the DMA when the new CTR_TX/CTR_RX interrupt is

received.

In fact the CPU needs to decode the endpoint to be served (to get the source and

the destination addresses) before programming the next DMA transfer because

multiple endpoints are mapped on the same channel (Tx/Rx).

UM0290 Datasheet(PDF) 11 Page - STMicroelectronics