Register Descriptions
1353
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Universal Serial Bus (USB) Controller
18.5.11 USB Test Mode Register (USBTEST), offset 0x00F
The USB test mode 8-bit register (USBTEST) is primarily used to put the USB controller into one of the
four test modes for operation described in the USB 2.0 Specification, in response to a SET FEATURE:
USBTESTMODE command. This register is not used in normal operation.
Note:
Only one of these bits should be set at any time.
Mode(s):
OTG A or Host
OTG B or Device
USBTEST in OTG A/Host Mode is shown in
and described in
Figure 18-15. USB Test Mode Register (USBTEST) in OTG A/Host Mode
7
6
5
4
0
FORCEH
FIFOACC
FORCEFS
Reserved
R/W-0
R/W1S-0
R/W-0
R-0
LEGEND: R/W = Read/Write; W = Write only; -
n
= value after reset
Table 18-18. USB Test Mode Register (USBTEST) in OTG A/Host Mode Field Descriptions
Bit
Field
Value
Description
7
FORCEH
Force Host Mode. While in this mode, status of the bus connection may be read using the DEV
bit of the USBDEVCTL register. The operating speed is determined from the FORCEFS bit.
0
No effect
1
Forces the USB controller to enter Host mode when the SESSION bit is set, regardless of
whether the USB controller is connected to any peripheral. The state of the USB0DP and
USB0DM signals is ignored. The USB controller then remains in Host mode until the SESSION
bit is cleared, even if a Device is disconnected. If the FORCEH bit remains set, the USB
controller re-enters Host mode the next time the SESSION bit is set.
6
FIFOACC
FIFO Access
0
No effect
1
Transfers the packet in the endpoint 0 transmit FIFO to the endpoint 0 receive FIFO.
5
FORCEFS
Force Full-Speed Mode
0
The USB controller operates at Low Speed.
1
Forces the USB controller into Full-Speed mode upon receiving a USB RESET.
4-0
Reserved
0
Reserved
USBTEST in OTG B/Device Mode is shown in
and described in
Figure 18-16. USB Test Mode Register (USBTEST) in OTG B/Device Mode
7
6
5
4
0
Reserved
FIFOACC
FORCEFS
Reserved
R-0
R/W1S-0
R/W-0
R-0
LEGEND: R/W = Read/Write; W = Write only; -
n
= value after reset
Table 18-19. USB Test Mode Register (USBTEST) in OTG B/Device Mode Field Descriptions
Bit
Field
Value
Description
7
Reserved
Force Host Mode. While in this mode, status of the bus connection may be read using the DEV
bit of the USBDEVCTL register. The operating speed is determined from the FORCEFS bit.
6
FIFOACC
FIFO Access
0
No effect
1
Transfers the packet in the endpoint 0 transmit FIFO to the endpoint 0 receive FIFO.