Conifgure Clock Tree for Mems oscillator on MHZXin and KHZXin pins

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joli_601446
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Hello, I'm using a Mems 25Mhz clock and a Mems 32.768Khz clock on the MHZXIN and KHZXIN respectfully. I need a little help setting up the clock tree in my project in PSOC Creator 4.1.

Here is my schematic:

PSOC5_CLOCK_CONN.jpg

Here is my clock settings:

PSOC_Clock_Setup.jpg

If anyone can give me some help I would greatly appreciate it.

Thanks,

Joe

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1 Solution

Hi Joe,

You are routing an external clock through the ECO pins. So you have to enable the XTAL and XTAL 32KHz block in the clocks tab instead of Digital Signal block. So please disable the "Digital Signal" block and enable "XTAL" block.

Once you check the blocks configure the clocks according to the specifications.

Please refer the below application note for detailed information.

http://www.cypress.com/file/141216/download

Thanks

Ganesh

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5 Replies
Roy_Liu
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5 comments on KBA First comment on KBA 10 questions asked

Hi Joe,

Please have a look at this thread - Oscillator digital clock on ECO input pins

Thsnk

Roy

Roy Liu
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Hello, thank you for responding to my post. This is my first PSOC design and I am not too familiar with the Clock Tree. I learned that you must double click in the Clocks to get the Configuration Window to appear. I disabled the XTAL and checked the Digital Signal Block. I don't know what to enter in this box I clicked the ellipse and picked the first item in the list. I enter the clock frequency of 25Mhz.

Here is my view.

CLOCK_SETTT.jpg

I'm not sure that I'm doing things right here. How do I tell the system that there is a 25Mhz clock on pin 43? What should show up in the Digital Signal Block for the Name edit box?

Joe

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Hi Joe,

You are routing an external clock through the ECO pins. So you have to enable the XTAL and XTAL 32KHz block in the clocks tab instead of Digital Signal block. So please disable the "Digital Signal" block and enable "XTAL" block.

Once you check the blocks configure the clocks according to the specifications.

Please refer the below application note for detailed information.

http://www.cypress.com/file/141216/download

Thanks

Ganesh

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Hello, thank all for the quick responses. I implemented your suggestions.

ClockSettings.jpg

How does this look so far. I'm a little confused with the instructions at Oscillator digital clock on ECO input pins . They suggest, "So summary is MHz ECO needs to be disabled and the same input pin can be used to give external digital clock. But KHz ECO needs to be enabled and connect external clock to the input pin of KHz ECO in PSoC."

How do I disable the MHz ECO? I thought this was done by not checking the XTAL block. Also, how does the system know that I'm not using a Crystal? Isn't it expecting a crystal connection?

Can you help explain this?

Joe

P.S. I'm using a MEMs oscillator because the environment in which this board will be placed has lots of vibrations.

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joli_601446
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Hello, I haven't heard back from anyone on this post. I still need some help. If anyone has done this before can you please let me know if my setup is correct?

Thank,s

JOe

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