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Registers

4.58 Control Status Register for Endpoint 0 in Host Mode (HOST_CSR0)

The Control Status Register for Endpoint 0 in Host Mode (HOST_CSR0) is shown in Figure 73 and described in Table 74.

Figure 73. Control Status Register for Endpoint 0 in Host Mode (HOST_CSR0)

15

 

 

 

 

11

10

9

8

 

 

 

Reserved

 

 

DATATOGWREN

DATATOG

FLUSHFIFO

 

 

 

 

R-0

 

 

W-0

R/W-0

W-0

7

 

6

 

5

4

3

2

1

0

NAK_TIMEOUT

STATUSPKT

REQPKT

ERROR

SETUPPKT

RXSTALL

TXPKTRDY

RXPKTRDY

W-0

R/W-0

 

R/W-0

W-0

R/W-0

R/W-0

R/W-0

R/W-0

LEGEND: R/W = Read/Write; R = Read only; W = Write only; -n= value after reset

 

 

 

 

Table 74. Control Status Register for Endpoint 0 in Host Mode (HOST_CSR0) Field Descriptions

Bit

Field

 

Value

Description

 

 

 

 

 

15-11

Reserved

 

0

Reserved

 

 

 

 

 

10

DATATOGWREN

0-1

Set this bit to enable the DATATOG bit to be written. This bit is automatically cleared once the new

 

 

 

 

value is written to DATATOG.

 

 

 

 

9

DATATOG

 

0-1

When read, this bit indicates the current state of the EP0 data toggle. If DATATOGWREN is high,

 

 

 

 

this bit can be written with the required setting of the data toggle. If DATATOGWREN is low, any

 

 

 

 

value written to this bit is ignored.

 

 

 

8

FLUSHFIFO

0-1

Set this bit to flush the next packet to be transmitted/read from the Endpoint 0 FIFO. The FIFO

 

 

 

 

pointer is reset and the TXPKTRDY/RXPKTRDY bit is cleared.

 

 

 

 

 

 

Note: FLUSHFIFO has no effect unless TXPKTRDY/RXPKTRDY is set.

 

7

NAK_TIMEOUT

0-1

This bit will be set when Endpoint 0 is halted following the receipt of NAK responses for longer than

 

 

 

 

the time set by the NAKLIMIT0 register. This bit should be cleared to allow the endpoint to

 

 

 

 

continue.

 

 

 

 

 

6

STATUSPKT

0-1

Set this bit at the same time as the TXPKTRDY or REQPKT bit is set, to perform a status stage

 

 

 

 

transaction. Setting this bit ensures that the data toggle is set so that a DATA1 packet is used for

 

 

 

 

the Status Stage transaction.

 

 

 

 

5

REQPKT

 

0-1

Set this bit to request an IN transaction. It is cleared when RXPKTRDY is set.

 

4

ERROR

 

0-1

This bit will be set when three attempts have been made to perform a transaction with no response

 

 

 

 

from the peripheral. You should clear this bit. An interrupt is generated when this bit is set.

3

SETUPPKT

0-1

Set this bit, at the same time as the TXPKTRDY bit is set, to send a SETUP token instead of an

 

 

 

 

OUT token for the transaction.

 

 

 

2

RXSTALL

 

0-1

This bit is set when a STALL handshake is received. You should clear this bit.

 

1

TXPKTRDY

0-1

Set this bit after loading a data packet into the FIFO. It is cleared automatically when the data

 

 

 

 

packet has been transmitted. An interrupt is generated (if enabled) when the bit is cleared.

0

RXPKTRDY

0-1

This bit is set when a data packet has been received. An interrupt is generated when this bit is set.

 

 

 

 

Clear this bit by setting the SERV_RXPKTRDY bit.

 

 

SPRUGH3–November 2008

Universal Serial Bus (USB) Controller

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