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Registers
1724
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
34.4.39 Control Status Register for Host Receive Endpoint (HOST_RXCSR)
The control status register for host receive endpoint (HOST_RXCSR) is shown in
and
described in
Figure 34-65. Control Status Register for Host Receive Endpoint (HOST_RXCSR)
15
14
13
12
11
10
9
8
AUTOCLEAR
AUTOREQ
DMAEN
DISNYET
DMAMODE
DATATOGWREN
DATATOG
Reserved
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
W-0
R/W-0
R-0
7
6
5
4
3
2
1
0
CLRDATATOG
RXSTALL
REQPKT
FLUSHFIFO
DATAERR_
NAKTIMEOUT
ERROR
FIFOFULL
RXPKTRDY
W-0
R/W-0
R/W-0
W-0
R-0
R/W-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; W = Write only; -
n
= value after reset
Table 34-69. Control Status Register for Host Receive Endpoint (HOST_RXCSR) Field Descriptions
Bit
Field
Value
Description
15
AUTOCLEAR
0
DMA Mode: The CPU sets the AUTOCLEAR bit prior to enabling the Rx DMA.
1
CPU Mode: If the CPU sets the AUTOCLEAR bit, then the RXPKTRDY bit will be
automatically cleared when a packet of RXMAXP bytes has been unloaded from the
Receive FIFO. When packets of less than the maximum packet size are unloaded,
RXPKTRDY will have to be cleared manually.
14
AUTOREQ
1
If the CPU sets the AUTOREQ bit, then the REQPKT bit will be automatically set when the
RXPKTRDY bit is cleared.
Note: This bit is automatically cleared when a short packet is received.
13
DMAEN
0-1
Set this bit to enable the DMA request for the Receive endpoints.
12
DISNYET
0-1
Set this bit to disable the sending of NYET handshakes. When set, all successfully received
Receive packets are ACKED including at the point at which the FIFO becomes full.
Note: This bit only has any effect in high-speed mode, in which mode it should be set for all
Interrupt endpoints.
11
DMAMODE
0-1
Always clear this bit to 0.
10
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.
9
DATATOG
0-1
When read, this bit indicates the current state of the Receive 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.
8
Reserved
0
Reserved
7
CLRDATATOG
0-1
Write a 1 to this bit to reset the endpoint data toggle to 0.
6
RXSTALL
0-1
When a STALL handshake is received, this bit is set and an interrupt is generated. You
should clear this bit.
5
REQPKT
0-1
Write a 1 to this bit to request an IN transaction. It is cleared when RXPKTRDY is set.
4
FLUSHFIFO
0-1
Write a 1 to this bit to flush the next packet to be read from the endpoint Receive FIFO. The
FIFO pointer is reset and the RXPKTRDY bit is cleared.
Note: FLUSHFIFO has no effect unless RXPKTRDY is set. Also note that, if the FIFO is
double-buffered, FLUSHFIFO may need to be set twice to completely clear the FIFO.
3
DATAERR_NAKTIMEOUT
0-1
When operating in ISO mode, this bit is set when RXPKTRDY is set if the data packet has
a CRC or bit-stuff error and cleared when RXPKTRDY is cleared. In Bulk mode, this bit will
be set when the Receive endpoint is halted following the receipt of NAK responses for
longer than the time set as the NAK Limit by the RXINTERVAL register. You should clear
this bit to allow the endpoint to continue.
2
ERROR
0-1
The USB controller sets this bit when 3 attempts have been made to receive a packet and
no data packet has been received. You should clear this bit. An interrupt is generated when
the bit is set.
Note: This bit is only valid when the transmit endpoint is operating in Bulk or Interrupt
mode. In ISO mode, it always returns zero.
1
FIFOFULL
0-1
This bit is set when no more packets can be loaded into the Receive FIFO.