i.mx6dl usb device disconnect from computer

[zhongweihe]

Our new project now customer feedback an issue is that  usb device disconnect from computer sometimes but it can recover connect immediately.

MCU module: MCIMX6U5EVM10AC

Action:

1. USB eye diagram test is OK ,

2. if USB device connected to computer then remove the usb cable , but measured the USB_OTG_VBUS still output 4.4V(all of the products) .could you please help how to shut down the USB_OTG_VBUS?

[zhongweihe]

Hi Igor:

       Today I mearsured the VDDUSB_CAP this voltage is 3.28V , but  the specification of i.mx6dl show that this voltage is 3V , and I measured the Demo board is 2.98V . could you please help me to check how can I to regulate it ? 

[igorpadykov]

Zhongwei

suggest to recheck board schematic using IMX6DQ6SDLHDG, Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families of Applic...

VDDUSB_CAP voltage can be regulated using PMU_REG_3P0n register described in

sect.51.7.2 Regulator 3P0 Register (PMU_REG_3P0n)

i.MX 6Solo/6DualLite Applications Processor Reference Manual

Best regards
igor

[zhongweihe]

Hi Igor:

    thanks your good support , i will try it .

[igorpadykov]

Hi zhongwei

for usb disconnection problem one can check 24MHz clock stability

and try to use short quality shielded usb cable.

For "shut down the USB_OTG_VBUS" one can check USB_ID signal of

i.MX6 board, when removing the usb cable signal should be high or floating state.

Best regards
igor
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[zhongweihe]

Hi Igorpadykov:

   Thanks your quick respond .

1. Check 24MHz clock stability----OK , I will check with the crystal manufactor about it .

2. use short usb cable ------our end user's USB cable is about 3m length , but the usb eye diagram test is oK . so the hardware part is good  I think .

3. USB_ID signal----how to check the USB_ID signal i can not find this signal . I measured the NXP demo board , if remove the usb cable from computor , the USB_OTG_VBUS is 0V but our is 4.4V .(the demo board MCU model is the same as our product)

[igorpadykov]

Hi zhongwei

suggest to change custom board design according to i.MX6Q Sabre SD schematic.

USB_OTG_VBUS can be found on p.11 i.MX6Q Sabre SD schematic:

Design files, including hardware schematics, Gerbers, and OrCAD files for i.MX 6Quad (i.MX 6Dual emu...

Best regards
igor

[zhongweihe]

Hi igorpadykov,

    Thanks your good support , up is our project about USB signal part .

1. Our USB not with OTG function ,

2. Signal USB_OTG_DN/USB_OTG_DP connect to USB type B connector directly as a device . 

3. First time power up ; 1.  if not connect USB cable to computer , the USB_OTG_VBUS =0V .

                                         2. if connect USB cable to computer ,the USB_OTG_VBUS =5V , then if remove the

                                             USB cable from computer ,the USB_OTG_VBUS=4.4V( Generallly , if remove the USB

                                             USB cable from computer , the USB_OTG_VBUS should be 0V) so please help to check

                                            why the USB_OTG_VBUS still output 4.4V if remove the USB cable from computer ?

[igorpadykov]

Hi zhongwei

had custom board design followed i.MX6Q Sabre SD schematic.

If not, suggest to proceed with help of Commercial Support and Engineering Services | NXP 

Best regards
igor