Sorry, you need to enable JavaScript to visit this website.

Power Rails monitoring

Solved
6 posts / 0 new
Umar_minhas's picture
Umar_minhas
Junior(0)
Power Rails monitoring

Hi,
 
Is there a way to monitor power rails for PS and PL on Mini-ITX board. I have monitored power on ZC702 using a TI adapter connected to the board before. I wish to do something similar on Mini-ITX. Is there a supporting tool kit available? Any external card or adapter that can be connected or any registers that can be read via PS? Or any points on the board that can be monitored using external power meters?
 
Thanks

ctammann's picture
ctammann
Moderator(0)
Unfortunately it's not supported

Unfortunately there is no telemetry on the Mini-ITX platform.  THE ZC702 board has a power architecture featuring PMBus communication.  Our UltraScale platform features PMBus, but the Mini-ITX platform does not.  Also, we do not have the PS and PL broken out to separate supplies on the Mini-ITX, meaning that if you did monitor them you would not get the granularity to see what the PS and PL were drawing individually. 

The GE power module does have PMBus capability, however it isn't built in to the rest of the system.  You would need to purchase a separate power module, as well as the GE dongle in order to communicate with the board.  Again, you still would not get the separation between the PS and PL supplies so if that is specfically what you are looking for then the GE solution may be more trouble than it's worth.

Here is the link to the GE board

https://products.avnet.com/shop/en/ema/kits-and-tools/development-kits/a...

Here is the direct link to the user guide for enabling PMBus.  It would require adding a header to the board and purchasing the dongle

https://products.avnet.com/opasdata/d120001/medias/docus/8/Avnet-AES-POM...

Sorry I don't have a simpler solution, but this functionality was not part of the requirements on this system and was not designed in.

Thanks

Chris

Umar_minhas's picture
Umar_minhas
Junior(0)
That was very helpful

Dear Chris,
Thanks a lot for your reply. That was really helpful. 
Just a few more questions regarding the solution you proposed.
If not a separation between PS and PL, can you let me know how much fine grained it is? Will I get the SoC power? What other rails it monitors?
It says it can possibly be connected via the base board (J4 connector) assuming that the baseboard also incorporates a 10 pin header similar to HDR1. I do not think Mini-ITX has that connector? I think I will need to connect the HDR1 connector to the GE board for connection with GE dongle.
The existing Panasonic Power Module will be replaced by this board. Right? 
Thanks again. 
Umar

ctammann's picture
ctammann
Moderator(0)
Hi Umar,

Hi Umar,

These rails provide power for the entire board, so getting an accurate measurement of just the SoC won't be very reliable.  I will say that the majority of the power consumption of the Zynq device comes from the core rail (1V).  The other rails are shared by other devices but the core supply only powers the Zynq.  If you look at an XPE design (Xilinx power estimator spreadsheet) you'll see that the majority of the power consumption comes from the core rail.  An easier experiment might be to just break the board to board connection on the 1V rail (you'd most likely need to cut that pin) then run that through either a multimeter or if you have a current probe create a loop that you could clip around.  That would allow you to measure the current just on the core supply.

You are correct, if you went with the GE module you would replace the Panasonic module that is currently installed on your board.  There is no mating connector on the Mini-ITX to communicate to the PMBus so you would need to add the external header.  The hooks were provided for this functionality, however this interface as never been tested so there may be some trial and error involved. 

Another thing to consider would be to add "risers" to the headers on the power module.  If you got some headers/sockets that you could raise the power module with, you could then use those points to break the connections between boards to add a multimeter or current loop for measurements.  If you went this route, only use the risers to take your current measurements.  Adding the connectors to the path will increase the trace inductance and could affect loop stability so you would not want to continuously run in that state.

Bottom line is there is some risk involved in both methods (added inductance / untested interface) since we did not design this system to offer that capability natively.  Sorry I can't propose a simpler solution.  Let me know what you think.

thanks

Chris

Umar_minhas's picture
Umar_minhas
Junior(0)
1 V rail is good enough

Hi Chris,
Thanks a lot. Yes 1 V rail will be a decent enough estimate for me. Sorry if I am being redundant but just to confirm you are saying 1V rail can be monitored via GE module, cable and toolkit OR by breaking the board connection on my current Panasonic module? 
It is pin 2 on J2 for 1V I think from schematic of GE board given here:  https://products.avnet.com/opasdata/d120001/medias/docus/8/Avnet-AES-POM...
I will talk to my supervisor here and see what he recommends. Buying new accessories vs taking the risk.
 
Thanks a lot.
Umar

ctammann's picture
ctammann
Moderator(0)
Hi Umar,

Hi Umar,

Yes, those are your two options.  You'll need to keep the remote sense connections in place (J3).  Again keep in mind that while the GE module does provide the hooks, that feature hasn't been tested so there is a degree of risk there.  Again, sorry there isn't a simpler solution, please let me know how it goes or if you have any other questions.

thanks

Chris