RM0319 datasheet(132/368 Pages) STMICROELECTRONICS

132 / 368 page

USB 2.0 Device ports (UDC)

RM0319

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Doc ID 022640 Rev 3

11.4.5

Data memory structure in DMA mode

SETUP data memory structure

The memory structure for SETUP data is given in Figure 41. The 16-byte buffer consists of 4

fields of 32 bits each: the status quadlet (its bit assignments are given in Table 37), a

reserved one and the 2 last fields for the 8 bytes of SETUP data.

Figure 41.

SETUP data memory

Table 37.

SETUP data memory: status quadlet bit assignments

Bit

Name

Description

[31:30]

Buffer status.

This 2 bit field reports the status of the SETUP data buffer, according to

encoding:

– 2‘b00 Host ready. = The descriptor is available to be processed by DMA.

– 2‘b01 DMA busy. = The DMA is still processing the descriptor.

– 2‘b10 DMA done. = Buffer data transfer completed by DMA.

– 2‘b11 Host busy. = The application is processing the descriptor.

[29:28]

Rx Sts

Receive status.

This 2 bit field reports the status of the received SETUP data (according to

encoding), reflecting whether the SETUP data has been correctly received or

some errors occurred:

– 2‘b00 = Success.

– 2‘b01 = DESERR (descriptor transfer error).

– 2‘b10 = Reserved.

– 2‘b11 = BUFFER (data transfer error).

[27:16]

Config Sts

Configuration status.

This 12 bit field echoes the status of the current configuration associated

with the SETUP packet for a control endpoint. Bits assignments for this field

are given:

– [27:24] = Configuration number.

– [23:20] = Interface number.

– [19:16] = Alternate setting number.

[15:00]

Reserved

Read: undefined. Write: should be zero.

Setup Buffer Pointer

Status Quadlet

Reserved

First 4 Bytes of Setup Data

Second 4 Bytes of Setup Data

Status Quadlet

Config Sts

Rx Sts

15:0

27:16

29:28

31:30

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