TUSB3200CPAH datasheet(22/93 Pages) TI

22 / 93 page

2–6

interrupt mask register is set, an MCU interrupt will be generated and the USB function reset (0x17) vector will appear

in the interrupt vector register (VECINT).

The function reset enable bit (FRSTE) in the USB control register (USBCTL) is used to control the extent to which

the internal logic is reset. The function reset enable bit is set to a 1 by the MCU to enable the USB reset to reset all

internal logic including the MCU. However, the shadow the ROM (SDW) and the USB function connect (CONT) bits

will not be reset. When this bit is set, the reset output (RSTO) signal from the device will also be active when a USB

reset occurs. This bit is not affected by USB reset.

2.2.5

USB Suspend and Resume Modes

All USB devices must support the suspend and resume modes. During the suspend mode, USB devices that are bus

powered must enter a low power suspend state. If the USB peripheral device is not bus powered, then entering the

low power suspend state is not required. A suspend condition is defined as a constant idle state on the bus for more

than 3.0ms. A USB device must actually be in the suspend state no more than 10 ms after the suspend condition is

detected. There are two ways for the TUSB3200 device to exit the suspend mode, which are 1) detection of USB

resume signaling and 2) detection of a local remote wake-up event.

2.2.5.1 USB Suspend Mode

When a suspend condition is detected on the USB, the suspend/resume logic will set the function suspend request

bit (SUSR) in the USB status register. As a result, the function suspend request interrupt (SUSR) will be generated.

To enter the low power suspend state and disable all TUSB3200 device clocks, the MCU firmware should set the idle

mode bit (IDL), which is bit 0 in the MCU power control (PCON) register. The instruction that sets the IDL bit will be

the last instruction executed before the MCU goes to idle mode. In idle mode, the MCU status is preserved. Note that

the low power suspend state is a state in which the TUSB3200 clocks are disabled and the IC will consume the least

amount of power possible.

2.2.5.2 USB Resume Mode

When the TUSB3200 is in a suspend state, any non-idle signaling on the USB will be detected by the suspend/resume

logic and device operation will be resumed. As a result of the resume signaling being detected, the TUSB3200 clocks

will be enabled, the function resume request bit (RESR) will be set, and the function resume request interrupt (RESR)

will be generated. The function resume request interrupt to the MCU will automatically clear the idle mode bit in the

PCON register. As a result, MCU operation will resume with servicing the new interrupt. After the RETI from the ISR,

the next instruction to be executed will be the one following the instruction that set the IDL bit. Note that if the low power

suspend state was not entered by setting the IDL bit, the clocks will already be enabled and the IDL bit will already

be cleared.

2.2.5.3 USB Remote Wake-up Mode

The TUSB3200 device has the capability to remotely wake-up the USB by generating resume signaling upstream.

Note that this feature must be enabled by the host software with the SET_FEATURE DEVICE_REMOTE_WAKEUP

request. The remote wake-up resume signaling should not be generated until the suspend state has been active for

at least 5 ms. In addition, the remote wake-up resume signaling must be generated for at least 1ms but for no more

than 15 ms. When the TUSB3200 is in the low power suspend state, asserting the external interrupt input (XINT) to

the device will enable the clocks and generate the XINT interrupt. The XINT interrupt to the MCU will automatically

clear the idle mode bit in the PCON register. As a result, MCU operation will resume with servicing the new interrupt.

After the RETI from the ISR, the next instruction to be executed will be the one following the instruction that set the

IDL bit. Please note that if the low power suspend state was not entered by setting the IDL bit, the clocks will already

be enabled and the IDL bit will already be cleared. When the firmware sets the remote wake-up request bit (RWUP)

in the USB control register, the suspend/resume logic will generate the resume signaling upstream on the USB.

2.2.6

Power Supply Sequencing

Turning power supplies on and off with a mixed 5-V/3.3-V system is an important consideration. To avoid possible

damage to the TUSB3200 device, proper power sequencing is required. The turnon requirement is that the 5-V and

TUSB3200CPAH 数据表(PDF) 22 Page - Texas Instruments

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