CCS/AM3358: About usb_ctrlx after reset

user1201164

Part Number: AM3358

Tool/software: Code Composer Studio

Hi,

Since there was a device not using USB at am335x, we tried to reduce power consumption by setting OTG_PWRDN and CM_PWRDN bits of usb_ctrlx to '1' referring to 'AM335x Schematic Checklist'.
As a precaution, when examining the values before setting, both were '1' (usb_ctrlx = 0x3C000007). According to TRM, the value at reset is 0x3C000000.
Does this mean that the description of TRM is incorrect about the value after Reset? Or should PWRDN bits be set to '0'? Or is there any other influence (JTAG is used).
As a result, should I set '1' in order to reduce power consumption or is it the same as default?
I wonder if you could give me some advice.

Best Regards,

Kouji Nishigata

over 6 years ago

0 Bin Liu over 6 years ago

TI__Guru**** 168211 points

Hi Kouji-san,

What is the OS?

I don't currently have a setup to check if the TRM information is correct or not. But you can set both bits OTG_PWRDN and CM_PWRDN to 1 to disable the USB PHY, which in turn reduces the power consumption as well.

0 user1201164 over 6 years ago in reply to Bin Liu

Expert 1770 points

Hi,

Thank you for the reply.

Although I do not use the OS, it is a story before OS startup in the first place.

> ou can set both bits OTG_PWRDN and CM_PWRDN to 1 to disable the USB PHY,
> which in turn reduces the power consumption as well.

I understood.
However, I do not know whether the default is which one, whether PHY at startup is ON or OFF.

For example, TRM is correctly turned off with MBR , TRM is wrong and it is OFF with Reset, or the value read from the register is "1", but it is actually ON.

I am in trouble because I can not explain to customers.

Best Regards,
Kouji Nishigata

0 Bin Liu over 6 years ago in reply to user1201164

TI__Guru**** 168211 points

Hi,

If the register bit is '1', the module is OFF. If the register bit is '0', the module is ON. Do you see power consumption differences with the two settings?

0 user1201164 over 6 years ago in reply to Bin Liu

Expert 1770 points

Hi,

Thank you for the reply.

We have not measured power consumption yet.
Because, this iquestion is what the specification is like.

Best Regards,

Kouji Nishigata

0 user1201164 over 6 years ago in reply to user1201164

Expert 1770 points

sorry,

> Because, this iquestion is what the specification is like.
It is a typo.

Because this question is to confirm what the specification is like.

Best Regards,

Kouji Nishigata

0 Bin Liu over 6 years ago in reply to user1201164

TI__Guru**** 168211 points

Sometimes you cannot examine the register reset value, for example, ROM might already changed it.
So you don't have to care the usb_ctrl register reset value, please just modify its bits to meet your requirement.

0 user1201164 over 6 years ago in reply to Bin Liu

Expert 1770 points

Resetting and stopping at 0x0002000, usb_ctrl 0/1 was 0x3C006007.
When we set it to Boot mode using USB, usb_ctrl 0 was 0x3c006004 (it advanced to 0x00024b0).
Is this correct?

Best Regards,
Kouji Nishigata

0 Bin Liu over 6 years ago in reply to user1201164

TI__Guru**** 168211 points

I don't have access to ROM code, but
0x3C006007 has bit[1:0]=11b, which means the USB PHY is powered down;
0x3c006004 has bit[1:0]=00b, which means the USB PHY is powered up;

0 Daisuke Maeda over 6 years ago in reply to Bin Liu

Guru 20205 points

Hi Bin-san,

Thank you for your reply.

Does bit[1:0] have to be changed to the required value, depending on the value of bit[1:0] checked in the user program?

Our customer wants to remove unnecessary code for fast boot and reduce power consumption.

Is it correct that bit[1:0] is 11b if USB is not used in boot mode?

Best regards,

Daisuke

0 Bin Liu over 6 years ago in reply to Daisuke Maeda

TI__Guru**** 168211 points

How to use the register to control the hardware is up to your design, you decide the USB PHY power states if USB is not used. What I can tell you is that setting the bit to 1 powers off the USB PHY while setting it to 0 powers on the USB PHY.

0 Daisuke Maeda over 6 years ago in reply to Bin Liu

Guru 20205 points

Hi Bin-san,

Thank you for your reply.

Our customer will change bit[1:0] to 11b in the user program.

Best regards,

Daisuke

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CCS/AM3358: About usb_ctrlx after reset