About USB power

[keisukewatanabe]

Dear support,

(The signal names are from the Vybrid reference circuit)

(Q1) We are planning to use USB0 as HOST mode only,

do we still need to connect USB0_VBUS power to USB0_VBUS_DETECT?

(Q2) There is a sample connection of switch J20 and J21 for HOST mode in the Reference circuit.

It seems to that USB0_VBUS is connected with P5V, which is always on.

Why this is not connected to the point after the over-current-detection IC (RefNo.U8)?

Note: In the power sequence of the datasheet, USB0_VBUS is supposed to be on

at the end of the sequence, but connecting P5V seems to violate the sequence.

[naoumgitnik · Accepted solution]

Dear Keisuke,

1.

VBUS_DETECT is used for additional OTG USB signaling. For details, please, see:

• ‘i.MX53xA Automotive and Infotainment Applications Processors, Rev. 6’, ‘Table 107. VBUS Comparators Thresholds’, p.147,
• USB signaling details briefly - http://www.cypress.com/?http://www.cypress.com/?docID=25471docID=25471http://www.cypress.com/?docID=25471, especially clause ‘Session Request Protocol (SRP)’.

As you can see, it is not applicable to the HOST mode. At the same time, I do not see how connecting it may harm...

2.

Regarding the updated power sequence for VBUS -  it is NA (Don't care)  in the latest Datasheet.

Regards, Naoum Gitnik.

[kubiznak_petr]

Hello Naoum,

can you please clarify what you mean by:

As you can see, it is not applicable to the HOST mode.

Do you mean USB0 on Vybrid can only work in the Device mode?!

We need to use two USB cameras on Vybrid, hence need both USB0 and USB1 channel to work in the Host mode. But we are having troubles with that, as the device is only recognized on USB1. We tried to play with kernel-menuconfig with no success. Can you please advice how to achieve that?

Thank you,

Petr