USB power configurations

[memaher]

Assuming I allocate both USB0 and USB1 as OTG ports, so they can act as either master or slave, is it possible to still be able to power the device from USB-only power? If so, can you advise how this can be achieved with regards connections to VIN_USB? This is a rather confusing scenario whereby:
1. during development we want USB0 to act as a slave device for debug/development – sourcing power directly from the USB port.
2. at runtime, we want USB0 and USB1 as host devices for peripherals – providing power as needed.

Can’t figure out how to achieve this without jumpers – any ideas?

Mat

[Neeraj Dantu]

Memaher,

USB OTG functionality can be enabled by exposing the USB_ID pin to the USB connector(instead of floating or pulling to GND).

In addition to USB_ID, special configuration is required to manage the power supply to and from the USB port in different configurations. If the port is functioning as a client port, power must be supplied to USB_VBUS+VIN_USB. If the port is functioning as a host, on board power switches should be enabled to supply power to the USB slave(done via USBx_DRVVBUS). The switching between the power in/out can be done using USB_ID(USB_ID controls USBx_DRVVBUS which can be used as enable signal to power out) and presence of VIN_USB as control signals.  If you are using a powered hub when using the port as a USB host, then no additional power configuration is necessary.

EDIT: Updating this to add info about USBx_DRVVBUS

Hope this helps,

Best,

Neeraj

 

• This reply was modified 5 years, 4 months ago by Neeraj Dantu. Reason: Add info about USBx_DRVVBUS

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