TUSB6250 datasheet(45/124 Pages) TI

45 / 124 page

8−4

SLLS535A − January 2004

TUSB6250

8.3

USBSTA: USB Status Register (XDATA at F008)

Each bit in the USBSTA register can generate an interrupt if its corresponding mask bit is set in the USBMSK

WAKCLK interrupt. All bits in this register are set by the hardware and can only be cleared by the MCU when

writing a 1 to the proper bit location (writing a 0 has no effect).

The USBSTA register (excluding the RSTR bit) is cleared by a power-up reset or a WDT reset. It can also be

cleared by a USB reset, when the function reset connection bit in the USBCTL register is set (FRSTE = 1).

The RSTR bit of the USBSTA register can only be cleared by a power-up reset or a WDT reset. A USB reset

sets this bit to 1.

765

43210

RSV

RSTR

SUSPR

RESUR

WAKCLK

SETUP

STPOW

R/O

R/C

BIT

NAME

RESET

FUNCTION

STPOW

SETUP overwrite bit. Set by the hardware when the setup packet is received, while there is already

a packet in the setup buffer. The MCU clears this bit by writing a 1 (writing 0 has no effect).

SETUP

SETUP transaction received bit. As long as SETUP is 1, IN and OUT on endpoint-0 is NAKed,

regardless of their real NAK bits value. The MCU clears this bit by writing a 1 (writing 0 has no effect).

WAKCLK

Wakeup clock request bit. When WAKCLK interrupt is enabled, this bit is set in response to the status

change on any of these pins: VBUS, P3.4, P3.5, CD1, or CD2. The interrupt generated due to this bit

in turn wakes up the core clock if it has been shut down during suspend, when the remote wakeup is

enabled.

WAKCLK = 0 No wakeup clock event (status change on the five GPIO pins) is detected since the last

time the MCU clears the related status change bit in USBWKUP.

WAKCLK = 1 Wakeup clock event (any status change on the five GPIO pins) is detected since the

last time the MCU clears the related status change bit in USBWKUP.

RESUR

Function resume request bit. The MCU clears this bit by writing a 1 (writing 0 has no effect).

RESUR

RESUR = 0

No function resume is detected.

RESUR = 1

Function resume is detected

SUSPR

Function suspended request bit. This bit is set in response to a global or selective suspend condition.

The MCU clears this bit by writing a 1 (writing 0 has no effect).

SUSPR = 0 No function suspend is detected.

SUSPR = 1 Function suspend is detected.

RSTR

Function reset request bit. This bit is set in response to the host initiating a port reset to the TUSB6250.

The USB function reset is the condition to set this bit, not clear this bit. The MCU clears this bit by writing

a 1 (writing 0 has no effect).

RSTR = 0 No function reset is detected.

RSTR = 1 Function reset is detected.

6−7

RSV

Reserved = 0

8.3.1 USB Suspend

The USB 2.0 specification requires that all USB devices must support the suspend state. The USB devices

begin the transition to the suspend state after they see a constant idle state on their upstream facing bus lines

for more than 3 ms. The device must actually be suspended, drawing only suspend current from the bus after

no more than 10 ms of bus inactivity on its port. The specification also requires that a device with remote

wakeup capability may not generate resume signaling, unless the bus has been continuously in the idle state

for 5 ms.

In other words, the specification allows all USB devices to enter suspend at any time between 3 ms to 10 ms

after bus idle. For USB high-speed capable devices, since there is an additional 0.125-ms revert-wait time

from high-speed to full-speed after 3-ms high-speed bus idle, the actual time it can enter suspend is between

3.125 ms to 10 ms.

TUSB6250 Datasheet(PDF) 45 Page - Texas Instruments

TUSB6250 Datasheet(HTML) 45 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL