USB4715

DS00002514B-page 20

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2022 Microchip Technology Inc. and its subsidiaries

5.1.8

HUB CONNECT STAGE (USB_ATTACH)

Once the hub registers are updated through default values, SMBus master, and OTP, the device firmware will enable

attaching the USB host by setting the USB_ATTACH bit in the HUB_CMD_STAT register. The device will remain in the

Hub Connect stage indefinitely until the VBUS function is deasserted/assertion of external RESET_N pin.

5.1.9

NORMAL MODE (NORMAL_MODE)

Lastly, the hub enters Normal Mode of operation. In this stage full USB operation is supported under control of the USB

Host on the upstream port. The device will remain in the normal mode until the operating mode is changed by the USB

Host.

If

RESET_N is asserted low, then Standby Mode is entered. The device may then be placed into any of the designated

hub stages. Asserting a soft disconnect on the upstream port will cause the hub to return to the Hub Connect stage until

the soft disconnect is negated.

Note:

Changes to hub registers made in OTP memory space are not visible via SMBus during CFG_SOC stage.

Any register which is modified via SMBus during SOC_CFG and also modified in the OTP memory will exit

the configuration stages with the value as programmed in the OTP memory.