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Observer cb_cross
Observer
377 Views
Registered: ‎08-10-2018

how to interpret result of mrd of PS SYSMON registers

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Specifically, I have a ZCU104 board.

More generically, I am looking for information regarding the ZU+ MPSoC PS SYSMON. 

I have searched the User Guides that make sense to me to look in.  I have googled.  I have searched these forums.  I cannot find the information necessary to decode the result of:

 

xsct% connect
xsct% targets -set -filter {name =~ "Cortex-A53 #0"}
xsct% rst -processor
xsct% mrd 0xffa50818

That is the address for the measurement of VCC_PSAUX, which should be 1.8V

The result was:

FFA50818:   00009940

In UG1087, I see that:

Bits [15:6] = 10-bit ADC measurement.
Bits [5:0] LSBs.

Which leaves the ADC measurement at 0x265. or 10 0110 0101 binary.

I don't see how that number comes out anything close to 1.8

As I've said, I can't find any documentation which says how to translate these measurements.

Any help will be much appreciated.

 

 

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1 Solution

Accepted Solutions
Moderator
Moderator
323 Views
Registered: ‎04-18-2011

Re: how to interpret result of mrd of PS SYSMON registers

Jump to solution

For a voltage sensor, generally the transfer function is 

V = ((ADC Code) / 2^nbits) * 3V

The sensor output is scaled by a 1/3 so you've to scale it back up again to go from raw codes to volts

0x256 is 598 in decimal

Divide by 2^10 is 0.583984375

x3 then gives about 1.75V

This detail can be found in ug580

Hope it helps

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Don’t forget to reply, kudo, and accept as solution.
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3 Replies
Moderator
Moderator
324 Views
Registered: ‎04-18-2011

Re: how to interpret result of mrd of PS SYSMON registers

Jump to solution

For a voltage sensor, generally the transfer function is 

V = ((ADC Code) / 2^nbits) * 3V

The sensor output is scaled by a 1/3 so you've to scale it back up again to go from raw codes to volts

0x256 is 598 in decimal

Divide by 2^10 is 0.583984375

x3 then gives about 1.75V

This detail can be found in ug580

Hope it helps

-------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------
Observer cb_cross
Observer
265 Views
Registered: ‎08-10-2018

Re: how to interpret result of mrd of PS SYSMON registers

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klumsde,
Thank you for the answer.
I never would have figured it out by the description in UG580. The ADC Transfer Function formula is never actually given.
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Moderator
Moderator
231 Views
Registered: ‎04-18-2011

Re: how to interpret result of mrd of PS SYSMON registers

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The user guide details the power supply sensor on page 41

Equation 2-13 shows this calculation

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Don’t forget to reply, kudo, and accept as solution.
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