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joe306
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Registered: ‎12-07-2018

I2C Clock Stretching Zynq Ultrascale+

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Hello, I'm working with the Zynq Ultrascale+ MPSOC FPGA and implementing my first HDMI output design. I'm looking at the TDP159 ReDriver and the SN65DP159 ReTimer. I was speaking with the vendor of the devices and he mentioned to see if the FPGA supports Clock Stretching on the I2C clock. So, I'm asking the members if Clock Stretching is supported?

 

Thank you

Joe

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patocarr
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Registered: ‎01-28-2008

@joe306 

  Adding to Avrum's insightful answer, you can find details of the PS I2C controller in the TRM document chapter 22, ug1085. https://www.xilinx.com/support/documentation/user_guides/ug1085-zynq-ultrascale-trm.pdf

  The controller supports clock stretching in both master & slave modes.

 

Thanks,

-Pat

 

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avrumw
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Registered: ‎01-23-2009

I don't know anything specific about the I2C controller in the MPSoC (I presume it is part of the PS and not an IP implemented in the PL), but....

It wouldn't be much of an I2C controller (and you wouldn't really be able to call it I2C) if it didn't support clock stretching. Clock stretching on the I2C bus is a fundamental part of the operation - it is clearly documented as part of the specification. A design that doesn't support clock stretching violates the specification, so isn't really I2C. Clock stretching support in the I2C master is not optional...

Avrum

joe306
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Registered: ‎12-07-2018

Hello, thank you for responding to my message. Everyday I'm learning something new.

Thank you

Joe

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watari
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Registered: ‎06-16-2013

Hi @joe306 

 

If my understanding is correct, you can control clock stretching on the I2C clock by software.

However, I don't think that you need to use it for redriver and retimer,,,

What do you achieve ?

 

Best regards,

joe306
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Registered: ‎12-07-2018

Hello, thank you for responding to my message. I'm not sure what I achieve, only the TI vendor said some FPGA's don't support Clock Stretching. If you say the device supports Clock Stretching, then that's all need to know. 

Thanks again and thanks for being patient with engineers like me.

Have a good day,

Joe

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patocarr
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Registered: ‎01-28-2008

@joe306 

  Adding to Avrum's insightful answer, you can find details of the PS I2C controller in the TRM document chapter 22, ug1085. https://www.xilinx.com/support/documentation/user_guides/ug1085-zynq-ultrascale-trm.pdf

  The controller supports clock stretching in both master & slave modes.

 

Thanks,

-Pat

 

Give kudos if helpful. Accept as solution if it solves your problem.
https://tuxengineering.com/blog

View solution in original post

joe306
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Registered: ‎12-07-2018

Wonderful! Thank you very much for responding.

Joe

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