imx6 USB OTG

[SreedharNair]

Hi,

I have designed an imx6 board and is in the process of soldering minimum components to it.

I have soldered the PMIC circuits and the voltages are OK. 

I have soldered the otg circuit and imx6 quad chip but have not soldered ram or flash etc.

I would like to know will the pc recognise the imx6 if usb otg is connected at this stage?

Regards,

Sreedhar

[SreedharNair]

@weidong_sun 

Hi,

I have been working on this

All voltages are good except VDDUSB_CAP which is reading only 1.6V 10uf and 220nf are connected to VDDUSB_CAP. USB OTG VBUS is at 5V. Please help.

Regards,

Sreedhar

[weidong_sun]

Hi,

For USB LDO regulator, it can be programmed in 25 mV steps, from 2.625V to 3.4 V, if only one of the VBUS voltages is present, then the regulator automatically selects this supply.

You can see this description in the reference manual, the minimum voltage is 2.625V, so 1.6V is impossible,

You'd better SMT a complete board before you start debugging.

B.R,

weidong

[SreedharNair]

@weidong_sun 

Hi, 

I made a complete board, But VDDUSB_CAP still remains at 1.6v, but if I provide 3 V manually to VDDUSB_CAP then the board is recognised as " SE Blank ARIK" , I am still not sure why VDDUSB_CAP is at 1.6V. Any ideas.

Regards,

Sreedhar

[SreedharNair]

Hi Guys,

Any help. Please.

Regards,

Sreedhar

[weidong_sun]

You solder the parts one by one manually, and test whether the USB OTG is normal after soldering the parts. It's hard to tell where the problem is!
It is recommended that you use the machine SMT method to produce several boards before you start debugging.

[SreedharNair]

@weidong_sun 

Hi,

Apart from the soldering method is there any chance that VDDUSB behaves in such a manner?

Also, could we use the board by manually feeding 3V to VSSUSB_CAP?

Regards,

Sreedhar

[weidong_sun]

Hi ,

See below,please!

>>I have soldered the otg circuit and imx6 quad chip but have not soldered ram or flash etc.

I don't really understand why you don't solder DDR and flash to the board. If you want a board to start working, Power, cpu, DDR, and Flash are the smallest systems.

>>I would like to know will the pc recognise the imx6 if usb otg is connected at this stage?

After the board is powered on, the ROM code inside the cpu will be the first to run, according to the configuration of BOOT_MODE[1:0] whether to boot from USB OTG or from the onboard flash, according to The configuration of Boot Configuration Select determines from which interface the flash starts. If the ROM CODE cannot read valid boot information from the flash, it will automatically switch the USB OTG interface and wait for booting from the USB OTG.

According to this boot process, in theory, your windows pc can recognize USB device, which should be HID compliance device.

But your PC USB needs to provide 5V power to the USB OTG VBUS of the cpu, because it is the input of the internal USB LDO.

Hope above information is helpful to you.

Have a nice day!

B.R,

weidong

[SreedharNair]

@weidong_sun 

Hi,

Thanks for your reply.

>> I don't really understand why you don't solder DDR and flash to the board. If you want a board to start working, Power, cpu, DDR, and Flash are the smallest systems.

I did it so as to test if the CPU is soldered properly and working, is there any way I can confirm that the cpu is currenly working? Also with the cpu alone the current draw is 30mA.

>>"After the board is powered on, the ROM code inside the cpu will be the first to run, according to the configuration of BOOT_MODE[1:0] whether to boot from USB OTG or from the onboard flash, according to The configuration of Boot Configuration Select determines from which interface the flash starts. If the ROM CODE cannot read valid boot information from the flash, it will automatically switch the USB OTG interface and wait for booting from the USB OTG."

I checked and found that Boot Mode 1 is 0V and Boot Mode 0 is 3V so in this case it is configured as USB OTG.

Also USB OTG VBUS is at 5V provided by the PMIC. 

I have still not soldered on DDR and flash. What would you recommend, that I perform some tests to check if CPUs is working? or check after soldering the ddr and flash?

Regards,

Sreedhar

[weidong_sun · Accepted solution]

Hi，See below, please!

1.It is strongly recommended that you solder PMIC, CPU, DDR, FLASH (EMMC/SD/NAND/NOR) to the PCB.
2. Measure whether all output voltages of the PMIC are correct.
3. Whether the 32.768KHz crystal is oscillating.
4. Whether the CPU POR_B pin is pulled high
5. Whether the USB OTG ID pin is pulled high with a 10K resistor.
6. Whether USB OTG VBUS is 5V from external USB HOST

[Note]For USB device mode, 5V should be supplied by USB HOST
7. Whether VDDUSB_CAP outputs 3.0V (probably 3.2V, also OK)
8. connect USB OTG to PC USB HOST via MicroUSB Cable. PC should drive it as HID compliance device.

Have a nice day!

B.R,

Weidong