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External Adc Clock - which solder pads do what

Posted: Mon Aug 10, 2020 6:39 pm
by BeRenz
I'm trying to modify a 125-14 so that it accepts clock for it's adc over sata. Is is correct that I therefore need to solder the resistors to the pads which are closer to the sma connector?
https://redpitaya.readthedocs.io/en/lat ... xtADC.html is a bit confusing, as the layout shown does not seem to be identical to the current version.
There is a photo attached with the current resistor configuration. (Edit: It would be attached, but for some reason with only a single post without any attachments my "attachment quota has been reached")
Best
Benjamin

Re: External Adc Clock - which solder pads do what

Posted: Tue Aug 11, 2020 4:02 pm
by alex123go
Hello BeRenz,

We successfully modified our Red Pitayas to accept a clock from the GPIO E2 connector. While it's not exactly what you're looking for, some steps are similar.

First, you need to remove R25 and R26, which are under the heatsink (you can unsolder or cut the 0 Ohm resistor).

Secondly, you need to solder 2 of the 3 pins of both row on the bottom of the FPGA. We used small portion of wire to solder the pads together.

The zoom layout of R23,R24,R27,R28 makes it difficult to determine which is which, but by looking at the angled capacitor, you can see the position of the resistor.
  1. If you want to connect a clock from an external source via the GPIO E2 connecter, you need to solder the 2 pins closer to the SMAs connector : R23,R24 (https://imgur.com/a/qWZyvsx, I also could not add attachments)
  2. If you want to route the clock via the FPGA, you need to solder the 2 pins farther from the SMAs R27,R28 (I've never tried this, there might be some particularities that I'm not aware)
The sata connectors are connected directly to the FPGA, so I think option 2 is best for you.

Good luck

Re: External Adc Clock - which solder pads do what

Posted: Tue Aug 11, 2020 6:48 pm
by BeRenz
Thank you for your quick answer, this helps me a lot. :)
Edit: 13.Aug.20 picture for reference
RedPitaya Resistors for extAdcClock:
https://imgur.com/a/Itj0smq

Re: External Adc Clock - which solder pads do what

Posted: Thu Aug 20, 2020 8:50 pm
by alex123go
You're welcome! :)

Did it worked?
I just learned that I'll have to do approximately the same thing for a project I have.

Re: External Adc Clock - which solder pads do what

Posted: Thu Nov 19, 2020 2:23 pm
by redpitaya
Black Friday 2020 is here!

Re: External Adc Clock - which solder pads do what

Posted: Wed Nov 03, 2021 3:14 pm
by marceluda
I've tried the same.

I've managed to get the clock signal in an "slave" STEMlab-125-14 from another STEMlab-125-14 (the master one) through SATA cable.

now I need to synchronize the ADC to this clock, so I unsoldered the crystal clock resistors and soldered the path to the R27 and R28 resistors.

But with this change, the "slave" STEMlab-125-14 device cannot boot any more. When I look at the serial terminal I see that the system is rebooting all the time. I updated the OS to the last stable ( like here: https://stackoverflow.com/questions/516 ... o-external ) but still have the saem problem.

Does anyone had this problem? Does anyone know how to solve it?

Re: External Adc Clock - which solder pads do what

Posted: Fri Nov 05, 2021 10:44 am
by redpitaya
No need to desolder the oscillator chip. The instructions are here:
https://redpitaya.readthedocs.io/en/lat ... T/top.html

You can also buy a already modified unit from our webshop.
https://redpitaya.com/product/stemlab-1 ... arter-kit/

Re: External Adc Clock - which solder pads do what

Posted: Mon Nov 08, 2021 8:58 am
by redpitaya
When we will release the multi-channel system, most likely in Q1 2022, there will be also an OS release for the SLAVE board that will allow a SLAVE unit to boot even if the local clock is not connected.
At the moment it looks like the multi-channel system release will happen in December.

Re: External Adc Clock - which solder pads do what

Posted: Sun Jan 16, 2022 1:47 pm
by mgraeser
Maybe have a look to this project, where some things you mention are documented and solved:
https://tknopp.github.io/RedPitayaDAQSe ... uster.html