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PSoC 5, 3 & 1 MCU

MaMi_1205306
Honored Contributor

Hi,

We are considering USBFS component for PSoC5LP.

Coded according to "USBFS_suspend" in Code Example.

Sleeps PSoC 5LP when there is no signal from the host for 3ms.

Wake up at the fall of USBIF Dp.

It works as expected.

However,

When the PC host side stops power supply and opens the USB signal line,

The USBIF Dp line voltage becomes unstable and PSoC5LP repeatedly wakes up and sleeps.

Do you know how to avoid this sleep and wake up behavior?

Regards,

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1 Solution
RodolfoGL
Employee

Once you wake-up, revert back the configuration. You should only pull-up while sleeping.

View solution in original post

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6 Replies
RodolfoGL
Employee

You can try to pull-up or pull-down the USB pin before putting the device to sleep.

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MaMi_1205306
Honored Contributor

Thank you for your reply.

Does it mean that the P15[6] pin setting of the USB Dp terminal is changed to a resistive pull-up / pull-down by API?

Regards,

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RodolfoGL
Employee

Yes. Refer to the PSoC 5LP datasheet, Table 6-7. USBIO Drive Modes.

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MaMi_1205306
Honored Contributor

Thank you for your advice.

I will try changing the drive mode of USB IO.

Regards,

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MaMi_1205306
Honored Contributor

As you advised, I was able to avoid indeterminacy by making USB IO resistive pull-up before entering sleep mode.

However, the resistive pullup of PSoC5LP is about 10 kΩ.

The USB 2.0 specification states that a pull-up resistor of about 1.5kΩ is required.

I think that this measure will not comply with USB 2.0.

Do you know any other best solution?

Regards,

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RodolfoGL
Employee

Once you wake-up, revert back the configuration. You should only pull-up while sleeping.

View solution in original post

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