UBS overcurrent

Luc Van Asch

USB0 is used as internal usb port. Overcurrent detection is not required. I would like the pin used for overcurrent protection release and use it for other purposes.

The overcurrent pin used in the demo board is GPIO3_17 as you can see in the code below. Wonder what I have to write in case overcurrent detection is not required?

/* pinmux for usb0 drvvbus */
static struct pinmux_config usb0_pin_mux[] = {
{"usb0_drvvbus.usb0_drvvbus", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"mcasp0_ahclkr.gpio3_17", OMAP_MUX_MODE7 | AM33XX_PULL_ENBL |
AM33XX_PIN_INPUT_PULLUP},
{NULL, 0},
};

Thx

over 13 years ago

0 Miroslav Kiradzhiyski XID over 13 years ago

TI__Mastermind 25235 points

Hi Luc,

Just remove it from the usb0 drvvbus pinmux config. Like this:

/* pinmux for usb0 drvvbus */
static struct pinmux_config usb0_pin_mux[] = {
{"usb0_drvvbus.usb0_drvvbus", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{NULL, 0},
};

Then you may use it in another pinmux config.

Best regards,
Miroslav

0 Biser Gatchev-XID over 13 years ago

TI__Guru**** 393215 points

Hi Luc,

Please also note that for Host mode on AM335X you will need to use USB0_DRVVBUS and USB0_VBUS pins. For an internal connection this can be achieved by driving an open-drain buffer from USB0_DRVVBUS and connecting its output to USB0_VBUS with a 4.7kOhm pullup to +5V. This is a hardware requirement for the USB PHY to function properly. There is no software workaround for this. As a reference you can check component U5B on page 16 of the Starter Kit schematics. It's driven from an USB hube there, but you'll get the idea.

0 Luc Van Asch over 13 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

Is the connection between USB0_DRVVBUS and USB0_VBUS required? Connect USB0_VBUS hard to +5V (input voltage psu) and left USB0_DRVVBUS unused. It works fine or am I just lucky?

0 Biser Gatchev-XID over 13 years ago in reply to Luc Van Asch

TI__Guru**** 393215 points

Are you working in Host mode on the AM335X side?

0 Luc Van Asch over 13 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

Yes, only in host mode.

0 Biser Gatchev-XID over 13 years ago in reply to Luc Van Asch

TI__Guru**** 393215 points

Then my guess is that you are lucky with your configuration. My suggestion is to include the above changes if you do a board revision.

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UBS overcurrent