AM335x USB Host detection

Markus B

Other Parts Discussed in Thread: LM3526

On my board i have connected USB0 as a Host. ID pin is connected directly to ground, USB0_DRVVBUS is driven enable pin of 5V power IC (LM3526M-H). USB0_VBUS is connected to the switsching Power of LM3526M-H. My problem is that there are no Power on VBUS, it is only there for 600ms, than DRVVBUS goes low and the Output of LM3526 is schwitched off. If i cut the connection of DRVVBUS to LM3526, DRVVBUS is just 100ms active, so in my opinion the VBUS pin detected something because it takes more time, but nevertheless something fails becuase DRVVBUS goes low. Has anyone an idea?

regards

Markus

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Markus,

You should check how much time VBUS takes to ramp-up and whether it's within the required limits (4.75 - 5.25V). Also you should have an USB device connected to your USB connector.

0 Markus B over 12 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

Hi Biser,

ramp-up time <2ms, the voltage is 5,05VDC, a device is also connected.

regards

Markus

0 Biser Gatchev-XID over 12 years ago in reply to Markus B

TI__Guru**** 393215 points

Markus, have you checked that the USB_ID pin is properly grounded?

0 Markus B over 12 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

Hi Biser,

yes, USB_ID is grounded via 0ohm.

regards

Markus

0 -DK- over 12 years ago

TI__Mastermind 27890 points

If =>4.4V is not present on USBn_VBUS within 100ms, the controller will assume the power supply is OC and will de-assert DRVVBUS. DRVVBUS will also de-assert if VBUS drops below 4.4V at any time.

Did you include the required => 120uF capacitance on your VBUS rail? If not, your endpoint could be causing VBUS to droop when it transitions from low power (100mA) to high power (500mA) mode as part of enumeration.

0 Markus B over 12 years ago in reply to -DK-

Prodigy 80 points

Hi DK,

as i written before, 5.05VDC are presented 2ms after rising edge of DRVVBUS and are present for 600ms. A 150uF capacitor is placed. I have proofed it with 220uF but the same failure.

Regards

Markus

0 peaves over 12 years ago in reply to Markus B

TI__Guru 62945 points

Do you have a USB peripheral connected to this port? If so, does it detect VBUS going high and pull-up DP or DM to indicate it is connected?

Regards,
Paul

0 Bin Liu over 12 years ago in reply to peaves

TI__Guru**** 168311 points

Are you running the kernel provided from AMSDK? does 'dmesg' command show any log related to enumeration?

0 Bin Liu over 12 years ago in reply to Bin Liu

TI__Guru**** 168311 points

One more test: do you see steady 5V on VBUS if no device connected to the port?

0 Markus B over 12 years ago in reply to Bin Liu

Prodigy 80 points

Hi Bin Li,

it doesn't matter wether something is connected or not, it always 600ms

regards

Markus

0 Bin Liu over 12 years ago in reply to Markus B

TI__Guru**** 168311 points

Markus,

Do you use TI AMSDK kernel?

if so, I assume you already modified musb_board_data in arch/arm/mach-omap2/board-am335xevm.c to configure USB0 as MUSB_HOST? It is MUSB_OTG by default.

And could you please apply the follow change to the kernel and provide the full kernel bootup log? We'd like to check if the MUSB interrupt log gives any clue.

diff --git a/drivers/usb/musb/ti81xx.c b/drivers/usb/musb/ti81xx.c
@@ -1073,7 +1073,7 @@ static irqreturn_t ti81xx_interrupt(int irq, void *hci)
                musb_writel(reg_base, USB_CORE_INTR_STATUS_REG, usbintr);
        musb->int_usb = (usbintr & USB_INTR_USB_MASK) >> USB_INTR_USB_SHIFT;

-       dev_dbg(musb->controller, "usbintr (%x) epintr(%x)\n", usbintr, epintr);
+       dev_err(musb->controller, "usbintr (%x) epintr(%x)\n", usbintr, epintr);

        if (musb->int_usb & MUSB_INTR_SOF) {
                musb->sof_cnt++;

0 Bin Liu over 12 years ago in reply to Bin Liu

TI__Guru**** 168311 points

Please connect a USB device after kernel boots up, then dump the log.

0 Markus B over 12 years ago in reply to Bin Liu

Prodigy 80 points

Hi Bin Liu,

i have solved the bug.

It was a stupid thing. I had a wrong configuration in the pinmux, the drvvbus pin was configured as a GPIO.

Thanks all for support.

0 Bin Liu over 12 years ago in reply to Markus B

TI__Guru**** 168311 points

Glad you got the issue solved. Thanks for the update.

Processors

Processors forum

AM335x USB Host detection