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u-s
Level 3
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Level 3

Hello

I want to use the EtherCAT slave function of XMC4800.
I am thinking of implementing it with the following clock configuration, about this clock source what there any restrictions?
- Clock source device -> XMC4800 -> PHY
For example, clock source device must using a external crystal High Precision Oscillator, or must using a external clock source, or XMC4800 and PHY each need a clock device?

Best regards

u-s

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ncbs
Moderator
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Moderator

Hi @u-s,

Notably, there should not be any difference. Below are the three operating modes which can be used as sources for High Precision Oscillator:

  1. External Crystal Mode: This mode is used when XTAL1 and XTAL2 are used to generate a high precision clock.
  2. External Clock Input Mode: This mode is used when an external clock is being supplied to Clock Generation Unit (CGU) from CLKIN pin, via the OSC_HP module, bypassing the oscillator circuit.
  3. Disabled: High precision oscillator settings are disabled. Only Internal Fast Oscillator can be used to generate system and peripheral clocks.

Both the "External Crystal Mode" and "External Clock Input Mode" produce the same intended results. These two options are provided to offer the flexibility in choosing the source for High Precision Oscillator.

Regards,
Nikhil

 
 

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ncbs
Moderator
Moderator 50 likes received 250 sign-ins 250 replies posted
Moderator

Hi @u-s,

Are you trying to change the clock source to an external oscillator?

What all DAVE APPS or components are you using in your project?

Regards,
Nikhil

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u-s
Level 3
First like given 10 replies posted 10 questions asked
Level 3

Hi, Nikhil

Yes, I am using a external clock source.
When using ECAT, can there be a difference in the PHY output clock(PHY_CLK25) by using a external crystal High Precision Oscillator and a external clock source as the clock source device?
Could you tell me this difference?

My clock system is as follows.

us_0-1646302370459.png

Best regards

u-s

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ncbs
Moderator
Moderator 50 likes received 250 sign-ins 250 replies posted
Moderator

Hi @u-s,

Notably, there should not be any difference. Below are the three operating modes which can be used as sources for High Precision Oscillator:

  1. External Crystal Mode: This mode is used when XTAL1 and XTAL2 are used to generate a high precision clock.
  2. External Clock Input Mode: This mode is used when an external clock is being supplied to Clock Generation Unit (CGU) from CLKIN pin, via the OSC_HP module, bypassing the oscillator circuit.
  3. Disabled: High precision oscillator settings are disabled. Only Internal Fast Oscillator can be used to generate system and peripheral clocks.

Both the "External Crystal Mode" and "External Clock Input Mode" produce the same intended results. These two options are provided to offer the flexibility in choosing the source for High Precision Oscillator.

Regards,
Nikhil

 
 
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u-s
Level 3
First like given 10 replies posted 10 questions asked
Level 3

Hi, Nikhil

Thank you for your response.

Depending on the content of the answer, if using an external clock source is used as the clock source device, the PHY output clock(PHY_CLK25) can be possible to supply the clock of the external PHY device?

Also, using an external clock source is used as the clock source device, is there any information about the output accuracy of the PHY output clock(PHY_CLK25)?

Best regards

u-s

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ncbs
Moderator
Moderator 50 likes received 250 sign-ins 250 replies posted
Moderator

Hi @u-s,

Yes, PHY_CLK25 will be able to drive the clock of the external PHY device. The signal will be accurate too for the same.

Regards,
Nikhil