UM0290 datasheet(12/76 Pages) STMICROELECTRONICS

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STR7/STR9 USB firmware library

UM0290

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Note:

In unlinked mode the DMA interface doesn’t mask/clear any CTR_TX/CTR_RX interrupt

(the CPU is responsible for this task).

–

IN Endpoint:

In unlinked mode only three endpoints can be mapped on the DMA channel using

the following functions:

void DMAUnlinkedModeTxConfig(u8 bEpNum ,u8 index):configure a IN

endpoint to use the DMA in unlinked mode.

bEpNum = Endpoint number: 0 to 9.

index

= Endpoint index: 0,1 or 2.

void DMAUnlinkedModeTxEnable(u8 index):Enable a IN Endpoint to

trigger Tx DMA request.

index

= Endpoint index: 0,1 or 2.

void DMAUnlinkedModeTxDisable(u8 index):Disable the trigger Tx DMA

request for the IN Endpoint.

index

= Endpoint index: 0,1 or 2.

–

OUT Endpoint

In unlinked mode up to 10 endpoints can be mapped in the DMA channel using

the following functions:

void DMAUnlinkedModeRxEnable(u8 bEpNum): Enable a OUT Endpoint to

trigger OUT DMA request.

bEpNum = Endpoint number: 0 to 9.

void DMAUnlinkedModeRxDisable(u8 bEpNum): Disable the trigger Rx

DMA request for the OUT Endpoint.

bEpNum = Endpoint number: 0 to 9.

DMA Linked Mode Functions

In this mode only a single endpoint can be mapped on the DMA channel (Tx/Rx).

The DMA can prepare linked lists (LLI) in order to manage multiple data packet

transfer without CPU intervention at the end of the single data packet transfer. The

DMA interface provides transfer requests to the DMA controller until the LLI is

completed. The CPU is only responsible for configuring the linked lists (descriptor

UM0290 Datasheet(PDF) 12 Page - STMicroelectronics