CYUSB3KIT-003 - how to control low power mode abilities?

[irvac_3453546]

hi,

For my Ux testing I need an ability to control Ux features of FX3 device.

For default config I see:

wU2DevExitLat            : 0x0000 (0 µs)

I need to change this latency. Is it possible? 

Thanks,

Irena

[Hemanth]

Hi Irena,

- Can you please which project are you referring when you mentioned 'wU2DevExitLat'?

- Also can you please provide more details of your requirement?

Regards,

Hemanth

[irvac_3453546]

hi Hemanth,

I have EZ-USB® FX3™ SDK kit for my experiments. I need to control an ability of FPGA to enter U2 and U3 states.

For now if I connect FPGA to some HUB it always stay in U0 since FPGA doesn't goes to Ux state.

I've checked the descriptor info and saw that wU2DevExitLat =0. I think this is why FPGA cannot go to low power state.

Hope it's more clear now

Thanks,

Irena

[Hemanth]

Hi Irena,

The Ux low power modes are for USB device. When you commented - 'ability of FPGA to enter U2 and U3 states', I think you meant the ability of the USB chip connected to FPGA to enter low power states.

In that case, please check if CyU3PUsbLPMDisable() is called in your application. If yes, then make sure it is called only when data transfer is ongoing. In that case FX3 should go to low power modes, provided the requests come from the Host.

Regards,

Hemanth

[irvac_3453546]

Thank you Hemanth.

Can I somehow change LTR value that USB chip reporting to xHCI?

Thanks,

Irena

[Hemanth]

Hi Irena,

I am not sure which LTR value you are referring. Can you please provide more details. And can you please let me know if my previous comment was clear?

Regards,

Hemanth

[Hemanth · Accepted solution]

Hi Irena,

Sorry for the long gap to get back to you. I was not aware that you are asking about Latency Tolerance Message. You can use the FX3 API CyU3PUsbSendDevNotification() to achieve the same.

Regards,

Hemanth