LOW POWER MODE for KL25Z USB MSD DEVICE

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LOW POWER MODE for KL25Z USB MSD DEVICE

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charanreddy
Contributor III

Hi,

can we use low power mode in kl25Z USB MSD ...?. If yes, then how to make the CPU to come out of Low power mode after inserting the device in to the Host.

Regards,

Charan

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1 Solution
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mjbcswitzerland
Specialist V

Hi

USB is "operational" only in RUN and WAIT modes and not in (very) low power modes.

However you can use very low power modes when you don't need USB operation and detect a USB host connection by connecting the USB +5V to a LLWU input (with suitable circuit). The device can then be woken by detecting this voltage being attached and operate in RUN/WAIT modes until it may be set back to a low power mode again.

Regards

Mark

Kinetis: http://www.utasker.com/kinetis.html

KL25: http://www.utasker.com/kinetis/FRDM-KL25Z.html / http://www.utasker.com/kinetis/TWR-KL25Z48M.html

LLWU: http://www.utasker.com/kinetis/LLWU.html

For the complete "out-of-the-box" Kinetis experience and faster time to market

:smileyinfo: Out-of-the-box support for 46 Kinetis boards and 10 IDEs (460 combinations from a single code source with no porting required)

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237 Views
mjbcswitzerland
Specialist V

Hi

USB is "operational" only in RUN and WAIT modes and not in (very) low power modes.

However you can use very low power modes when you don't need USB operation and detect a USB host connection by connecting the USB +5V to a LLWU input (with suitable circuit). The device can then be woken by detecting this voltage being attached and operate in RUN/WAIT modes until it may be set back to a low power mode again.

Regards

Mark

Kinetis: http://www.utasker.com/kinetis.html

KL25: http://www.utasker.com/kinetis/FRDM-KL25Z.html / http://www.utasker.com/kinetis/TWR-KL25Z48M.html

LLWU: http://www.utasker.com/kinetis/LLWU.html

For the complete "out-of-the-box" Kinetis experience and faster time to market

:smileyinfo: Out-of-the-box support for 46 Kinetis boards and 10 IDEs (460 combinations from a single code source with no porting required)

View solution in original post

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236 Views
charanreddy
Contributor III

Hi Mark,

Thank you very much for your quick replay.

While doing this i came across "USB Transceiver Control Register 0 (USBx_USBTRC0) " in the KL25Z data sheet. Is it required to use this register if i am fallowing the above method mentioned by you. I am a bit confused by the reading the description of the "USBx_USBTRC0" register.

Regards,

Charan

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mjbcswitzerland
Specialist V

Hi

USBx_USBTRC0 is used to command a reset to the USB controller. It is generally used when configuring USB but won't necessarily be required to control low power operation or to recover from it. In low power mode all clocks to the USB controller will be stopped.

Regards

Mark