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Registers
1716
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
34.4.30 Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
The index register for selecting the endpoint status and control registers (INDEX) is shown in
and described in
Figure 34-56. Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
7
4
3
0
Reserved
EPSEL
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 34-60. Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
Field Descriptions
Bit
Field
Value
Description
7-4
Reserved
0
Reserved
3-0
EPSEL
0-4h
Each transmit endpoint and each receive endpoint have their own set of control/status registers. EPSEL
determines which endpoint control/status registers are accessed. Before accessing an endpoint's
control/status registers, the endpoint number should be written to the Index register to ensure that the
correct control/status registers appear in the memory-map.
34.4.31 Register to Enable the USB 2.0 Test Modes (TESTMODE)
The register to enable the USB 2.0 test modes (TESTMODE) is shown in
and described in
.
Figure 34-57. Register to Enable the USB 2.0 Test Modes (TESTMODE)
7
6
5
4
3
2
1
0
FORCE_HOST
FIFO_ACCESS
FORCE_FS
FORCE_HS
TEST_PACKET
TEST_K
TEST_J
TEST_SE0_NAK
R/W-0
W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; W = Write only; -
n
= value after reset
Table 34-61. Register to Enable the USB 2.0 Test Modes (TESTMODE) Field Descriptions
Bit
Field
Value
Description
7
FORCE_HOST
0-1
Set this bit to forcibly put the USB controller into Host mode when SESSION bit is set,
regardless of whether it is connected to any peripheral. The controller remains in Host mode
until the Session bit is cleared, even if a device is disconnected. And if the FORCE_HOST but
remains set, it will re-enter Host mode next time the SESSION bit is set. The operating speed is
determined using the FORCE_HS and FORCE_FS bits.
6
FIFO_ACCESS
0-1
Set this bit to transfer the packet in EP0 Tx FIFO to EP0 Receive FIFO. It is cleared
automatically.
5
FORCE_FS
0-1
Set this bit to force the USB controller into full-speed mode when it receives a USB reset.
4
FORCE_HS
0-1
Set this bit to force the USB controller into high-speed mode when it receives a USB reset.
3
TEST_PACKET
0-1
Set this bit to enter the Test_Packet test mode. In this mode, the USB controller repetitively
transmits a 53-byte test packet on the bus, the form of which is defined in the Universal Serial
Bus Specification Revision 2.0. Note: The test packet has a fixed format and must be loaded
into the Endpoint 0 FIFO before the test mode is entered.
2
TEST_K
0-1
Set this bit to enter the Test_K test mode. In this mode, the USB controller transmits a
continuous K on the bus.
1
TEST_J
0-1
Set this bit to enter the Test_J test mode. In this mode, the USB controller transmits a
continuous J on the bus.
0
TEST_SE0_NAK
0-1
Set this bit to enter the Test_SE0_NAK test mode. In this mode, the USB controller remains in
high-speed mode, but responds to any valid IN token with a NAK.