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USB superspeed peripherals

Level 2
Level 2


According to this knowledge base article:Low Power Modes in FX3, FX3S, CX3, SD3, FX2G2, and SD2 – KBA225742

There are L2, L3 and L4 low power modes for FX3S when operating at usb 2.0 mode.

Reference the LowPowerTest project in the SDK:


Only the 0xE3 command works in my system. And I send the command, the USB device disappear in the control center.


What should I do to correctly put the FX3s in the L2 mode and wake up by the host sending any USB command?

1 Solution
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- It is not mandatory to disconnect the USB during SUSPEND mode. In fact, when using USB bus activity as the wake up source, the USB must NOT be disconnected.

- To test the working of vendor command 0xE5, modify the configuration descriptors (SuperSpeed, High Speed and Full Speed) in the LowPowerTest firmware as follows. This modification enables the driver to put the device into U3 (USB Suspend) mode. When the device enters the U3 mode, the CY_U3P_USB_EVENT_SUSPEND event gets generated, which in turn sets the glTriggerSuspend parameter to CyTrue. Now, the UART logs can be seen to indicate the device entering the L2 suspend mode with USB bus activity as the wake-up source. Any activity on the USB Control Center/ communication with the device will result in waking up the device.

0x80,                          /* Config characteristics - Bus powered */

0xA0,                          /* Config characteristics - Bus powered */

Best regards,

Srinath S

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