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Visitor
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Registered: ‎10-17-2016

Using the XADC while PL is turned off

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Hi,

 

I developped an application in C that runs in the PS. It monitors and controls the Zynq power rails by controlling a Power Supply Sequencer, namely the TI UCD90120. This application has been tested successfully on two boards mounting a Zynq 7000 device: the Xilinx ZC706 commercial board and a custom board designed by my company.

 

A part the PMBus, the application uses the XADC through the PS dedicated interface to measure the device temperature and to monitor the voltage of some rails (VCCINT, VCCPINT).

One of the feature of the application is the possibility to turn off the PL by commanding the Power Supply Sequencer to set the VCCINT rail to 0.

Once the PL has been turned off the XADC stop working correctly, returning arbitrary values for voltage and a fixed meaningless value for temperature. Notice that this happens only on the custom designed board, whereas the XADC continues to work correctly on the ZC706.

 

I have checked that the power supply of the XADC on the custom board is not dependent from VCCINT, i.e the PL power rail.

 

Does anybody have suggestions about what else I should eb looking for? Maybe clock generation?

 

Thank you

 

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Moderator
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Registered: ‎04-18-2011

Re: Using the XADC while PL is turned off

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Hi @tpoggi 

 

I am not surprised that it is not working when PL VCCINT is removed. 

The XADC is in the PL. 

It has a 1.8V rail for the ADC, however the the register map, drp and sequencer all rely on the 1V VCCINT supply for the logic. 

 

Also the clock that drives the block will be on a BUFG so that is powered by VCCINT. 

 

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Moderator
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Registered: ‎04-18-2011

Re: Using the XADC while PL is turned off

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Hi @tpoggi 

 

I am not surprised that it is not working when PL VCCINT is removed. 

The XADC is in the PL. 

It has a 1.8V rail for the ADC, however the the register map, drp and sequencer all rely on the 1V VCCINT supply for the logic. 

 

Also the clock that drives the block will be on a BUFG so that is powered by VCCINT. 

 

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Moderator
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Registered: ‎04-18-2011

Re: Using the XADC while PL is turned off

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I suspect an examination of VCCINT on the ZC706 would show it is shared with some other supply that you have not powered off hence it still "works"

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