USB Registers
1713
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Serial Bus (USB) Controller
27.5.11 USBTEST Register (Offset = 0xF) [reset = 0x0]
USB Test Mode (USBTEST)
OTG A / Host
OTG B / Device
USBTEST is an 8-bit register that 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.
USBTEST for OTG A / Host is shown in
and described in
USBTEST for OTG B / Device is shown in
and described in
Return to
Figure 27-15. USBTEST Register (OTG A / Host)
7
6
5
4
3
2
1
0
FORCEH
FIFOACC
FORCEFS
FORCEHS
TESTPKT
TESTK
TESTJ
TESTSE0NAK
R/W-0x0
R/W1S-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
R/W-0x0
Table 27-20. USBTEST Register Field Descriptions (OTG A / Host)
Bit
Field
Type
Reset
Description
7
FORCEH
R/W
0x0
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 and
FORCEHS bit.
The operating speed is as follows: FORCEHS = 0 and FORCEFS =
0: Low Speed FORCEHS = 0 and FORCEFS =
1: Full Speed FORCEHS = 1 and FORCEFS =
0: High Speed FORCEHS = 1 and FORCEFS =
1: Undefined
0x0 = No effect.
0x1 = 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
R/W1S
0x0
FIFO Access.
This bit is cleared automatically.
0x0 = No effect.
0x1 = Transfers the packet in the endpoint 0 transmit FIFO to the
endpoint 0 receive FIFO.
5
FORCEFS
R/W
0x0
Force Full-Speed Mode.
If FORCEH is set, then this bit is used in combination with
FORCEHS to determine the operating speed.
If FORCEH is not set, then this operates as:
0x0 = The USB controller operates at Low Speed.
0x1 = Forces the USB controller into Full-Speed mode upon
receiving a USB RESET.
4
FORCEHS
R/W
0x0
Force High-Speed Mode.
If FORCEH is set, then this bit is used in combination with
FORCEFS to determine the operating speed.
If FORCEH is not set, then this operates as:
0x0 = The USB controller operates at Low Speed.
0x1 = Forces the USB controller into High-Speed mode upon
receiving a USB RESET.