USB Host Device Detection Without USBID or USBVBUS

Amanda Frame

Other Parts Discussed in Thread: TM4C129EKCPDT, EK-TM4C1294XL

I am trying to connect a TM4C129EKCPDT to a USB device (either a flash drive or a tablet). The microcontroller should always behave as a USB host so there is no USB ID or VBUS connections to it only the D+/D- data lines. When the tablet is connected the D+ line is pulled up to ~650mV (full speed device) but the microcontroller does not detect that a device was connected.

The stack mode is configured at USBModeForceHost and the USBHCDInit is called in the application initialization. The USB interrupts appear to be configured correctly.

The application and hardware were previously working in the OTG configuration when the ID pin was used for interrupt detection but that is longer an option for this system.

Thanks.

over 9 years ago

0 Amit Ashara over 9 years ago

TI__Guru**** 244400 points

Hello Amanda,

When using USB in force host mode, you need to make sure that the other side is not trying to negotiate or start a HNP. The simplest thing to try would be to force the host mode with a simpler device like a keyboard/mouse/usb thumb drive and see if it works; before using a tablet,

Regards
Amit

0 Amanda Frame over 9 years ago in reply to Amit Ashara

Prodigy 210 points

Thank you for the suggestion, unfortunately it looks like even a flash drive will not communicate (when it had before when using the OTG protocol and the ID pin). It seems like the microcontroller is not causing an interrupt to indicate a device has been connected.

Thanks.

0 Amit Ashara over 9 years ago in reply to Amanda Frame

TI__Guru**** 244400 points

Hello Amanda

Are you using the following function call?

USBStackModeSet(0, eUSBModeForceHost, 0);

Regards
Amit

0 Amanda Frame over 9 years ago in reply to Amit Ashara

Prodigy 210 points

USBStackModeSet(0, eUSBModeForceHost, &internalModeCallback);

// register the host class drivers
USBHCDRegisterDrivers(0, HOST_CLASS_DRIVERS, NUM_HOST_CLASS_DRIVERS);

// Initialize the power configuration. This sets the power enable signal
// to be active high and does not enable the power fault.
USBHCDPowerConfigInit(0, USBHCD_VBUS_AUTO_HIGH | USBHCD_VBUS_FILTER);

USBHCDInit(0, hcdMemoryPool, HCD_MEMORY_SIZE);

Thanks,
Amanda

0 Amit Ashara over 9 years ago in reply to Amanda Frame

TI__Guru**** 244400 points

Hello Amanda

And how is the USB device powered?

Regards
Amit

0 Amanda Frame over 9 years ago in reply to Amit Ashara

Prodigy 210 points

It is powered from an external power supply (battery or wall power) through a power switch. The power switch is controlled with the USB0_EPEN signal. When I have the processor in Host mode the USB0_EPEN is set high and I am seeing 5V on VBUS at the USB connector.

Thanks,
Amanda

0 Amit Ashara over 9 years ago in reply to Amanda Frame

TI__Guru**** 244400 points

Hello Amanda

The configuration seems correct. However I would suggest running the test on a EK-TM4C1294XL so that I can have a reference for your code when it does not work on the launchpad.

Regards
Amit

0 Amanda Frame over 9 years ago in reply to Amit Ashara

Prodigy 210 points

This issue has been corrected with a hardware change.

Thanks for the help,
Amanda

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USB Host Device Detection Without USBID or USBVBUS