
9397 750 13258
Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet
Rev. 01 — 12 January 2005
109 of 158
Philips Semiconductors
ISP1761
Hi-Speed USB OTG controller
10.5.2
Control Function register (R/W: 0228h)
The Control Function register performs the buffer management on endpoints. It consists
of 1 B, and the bit configuration is given in
Table 108
. The register bits can stall, clear or
validate any enabled data endpoint. Before accessing this register, the Endpoint Index
register must be written first to specify the target endpoint.
[1]
The reserved bits should always be written with the reset value.
10.5.3
Data Port register (R/W: 0220h)
This 2 B register provides direct access for a microcontroller to the FIFO of the indexed
endpoint. The bit description is shown in
Table 110
.
Table 108: Control Function register: bit allocation
Bit
7
Symbol
Reset
0
Bus reset
0
Access
R/W
6
5
4
3
2
1
0
reserved
[1]
0
0
R/W
CLBUF
0
0
R/W
VENDP
0
0
R/W
DSEN
0
0
R/W
STATUS
0
0
R/W
STALL
0
0
R/W
0
0
R/W
Table 109: Control Function register: bit description
Bit
Symbol
Description
7 to 5 -
reserved
4
CLBUF
Clear Buffer:
Logic 1 clears the RX buffer of the indexed endpoint; the TX
buffer is not affected. The RX buffer is automatically cleared once the endpoint
is completely read. This bit is set only when it is necessary to forcefully clear
the buffer.
3
VENDP
Validate Endpoint:
Logic 1 validates the data in the TX FIFO of an IN endpoint
for sending on the next IN token. In general, the endpoint is automatically
validated when its FIFO byte count has reached the endpoint MaxPacketSize.
This bit is set only when it is necessary to validate the endpoint with the FIFO
byte count that is below the Endpoint MaxPacketSize.
2
DSEN
Data Stage Enable
: This bit controls the response of the ISP1761 to a control
transfer. When this bit is set, the ISP1761 goes to the data stage; otherwise, the
ISP1761 will NAK the data stage transfer until the firmware explicitly responds
to the setup command.
1
STATUS
Status Acknowledge:
Only applicable for control IN and OUT.
This bit controls the generation of ACK or NAK during the status stage of a
SETUP transfer. It is automatically cleared when the status stage is completed
and a SETUP token is received. No interrupt signal will be generated.
0 —
Sends NAK
1 —
Sends an empty packet following the IN token (host-to-peripheral) or ACK
following the OUT token (peripheral-to-host).
0
STALL
Stall Endpoint
: Logic 1 stalls the indexed endpoint. This bit is not applicable for
isochronous transfers.
Remark:
‘Stall’ing a data endpoint will confuse the Data Toggle bit regarding
the stalled endpoint because the internal logic starts from where it is stalled.
Therefore, the Data Toggle bit must be reset by disabling and re-enabling the
corresponding endpoint (by setting bit ENABLE to logic 0 or logic 1 in the
Endpoint Type register) to reset the PID.