Registers
1721
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
34.4.36 Control Status Register for Host Transmit Endpoint (HOST_TXCSR)
The control status register for host transmit endpoint (HOST_TXCSR) is shown in
and
described in
Figure 34-62. Control Status Register for Host Transmit Endpoint (HOST_TXCSR)
15
14
13
12
11
10
9
8
AUTOSET
Reserved
MODE
DMAEN
FRCDATATOG
DMAMODE
DATATOGWREN
DATATOG
R/W-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
W-0
R/W-0
7
6
5
4
3
2
1
0
NAK_TIMEOUT
CLRDATATOG
RXSTALL
SETUPPKT
FLUSHFIFO
ERROR
FIFONOTEMPTY
TXPKTRDY
R/W-0
W-0
R/W-0
R/W-0
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 34-66. Control Status Register for Host Transmit Endpoint (HOST_TXCSR)
Field Descriptions
Bit
Field
Value
Description
15
AUTOSET
0
DMA Mode: The CPU needs to set the AUTOSET bit prior to enabling the Tx DMA.
1
CPU Mode: If the CPU sets the AUTOSET bit, the TXPKTRDY bit will be automatically set when
data of the maximum packet size (value in TXMAXP) is loaded into the Tx FIFO. If a packet of less
than the maximum packet size is loaded, then the TXPKTRDY bit will have to be set manually.
14
Reserved
0
Reserved
13
MODE
0-1
Set this bit to enable the endpoint direction as Tx, and clear the bit to enable it as Rx.
Note: This bit has any effect only where the same endpoint FIFO is used for both Transmit and
Receive transactions.
12
DMAEN
0-1
Set this bit to enable the DMA request for the Tx endpoint.
11
FRCDATATOG
0-1
Set this bit to force the endpoint data toggle to switch and the data packet to be cleared from the
FIFO, regardless of whether an ACK was received. This can be used by Interrupt Tx endpoints that
are used to communicate rate feedback for Isochronous endpoints.
10
DMAMODE
0-1
This bit should always be set to 1 when the DMA is enabled.
9
DATATOGWREN
0-1
Write 1 to this bit to enable the DATATOG bit to be written. This bit is automatically cleared once
the new value is written to DATATOG.
8
DATATOG
0-1
When read, this bit indicates the current state of the Tx EP 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.
7
NAK_TIMEOUT
0-1
This bit will be set when the Tx endpoint is halted following the receipt of NAK responses for longer
than the time set as the NAKLIMIT by the TXINTERVAL register. It should be cleared to allow the
endpoint to continue.
Note: This is valid only for Bulk endpoints.
6
CLRDATATOG
0-1
Write a 1 to this bit to reset the endpoint data toggle to 0.
5
RXSTALL
0-1
This bit is set when a STALL handshake is received. The FIFO is flushed and the TXPKTRDY bit is
cleared (see below). You should clear this bit.
4
SETUPPKT
0-1
Set this bit at the same time as TXPKTRDY is set, to send a SETUP token instead of an OUT
token for the transaction.
Note: Setting this bit also clears the DATATOG bit.
3
FLUSHFIFO
0-1
Write a 1 to this bit to flush the next packet to be transmitted from the endpoint Tx FIFO. The FIFO
pointer is reset and the TXPKTRDY bit (below) is cleared.
Note: FlushFIFO has no effect unless the TXPKTRDY bit is set. Also note that, if the FIFO is
double-buffered, FLUSHFIFO may need to be set twice to completely clear the FIFO.
2
ERROR
0-1
The USB controller sets this bit when 3 attempts have been made to send a packet and no
handshake packet has been received. You should clear this bit. An interrupt is generated when the
bit is set. This is valid only when the endpoint is operating in Bulk or Interrupt mode.
1
FIFONOTEMPTY
0-1
The USB controller sets this bit when there is at least 1 packet in the Tx FIFO.
0
TXPKTRDY
0-1
Set this bit after loading a data packet into the FIFO. It is cleared automatically when a data packet
has been transmitted. An interrupt is generated (if enabled) when the bit is cleared.