Pluto external clock input

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g6hfs
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Joined: Thu May 26, 2022 3:13 pm

Pluto external clock input

Post by g6hfs » Fri Jan 20, 2023 1:17 am

Hi,

I am not getting an external clock input working with my pluto rev d and firmware version v0.31-4-g9ceb-dirty, after setting up with the commands am I missing something.

I am using a tcxo mounted on a pcb with a decoupling cap with the output directly connected to the ext clk in.

fw_setenv refclk_source external
fw_setenv ad936x_ext_refclk_override 40000000
pluto_reboot reset

any help please, are the commands different ?

Brian
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g0mjw
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Re: Pluto external clock input

Post by g0mjw » Fri Jan 20, 2023 10:29 am

I assume you checked the TCXO is working and the level is correct. First thing to check.

Are you using Rev B firmware with a Rev D Pluto?

Best place to ask is on the AD forum.

When I tested one I used

fw_setenv refclk_source external
fw_setenv ad936x_ext_refclk_override 40000000

but that was with the stock firmware.


Mike

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g6hfs
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Re: Pluto external clock input

Post by g6hfs » Fri Jan 20, 2023 11:17 am

Hi Mike,

The TXCO is working on my hitachi 100Mhz dual trace scope it reads one div under 1 vols, so about 800mv.

The pluto Rev D on its pcb has been setup as per the portsdown 4 setup page, the pluto does tx ok and reports set to external with fw_printenv | grep refclk_source.

It’s if I disconnect the external clock the pluto still transmits ok, does it switch back to internal with no external clk, as it still reports using exteral clk with fw_printenv | grep refclk_source

Brian
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g0mjw
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Re: Pluto external clock input

Post by g0mjw » Fri Jan 20, 2023 1:21 pm

Brian,

Good, the clock is working, but it does sound a little low in level.

Most of us have Rev B plutos so can't really help. I know it worked when I modified one for someone, but that was with the unmodified firmware. You are using version 0.31.dirty which means it is custom firmware. Custom firmware can break things. Perhaps it is resetting the setting on a power cycle?

The official firmware is now up to 0.35. If you try it with that and it works then that determines where the problem is. If it still doesn't work with the latest unmodified firmware, then the best place for support for things like external clocks you is the AD forum.

e.g. https://ez.analog.com/adieducation/univ ... rnal-clock and https://ez.analog.com/adieducation/univ ... dalm-pluto

The AMSAT DL forum is also a good place to look and there is a thread on rev C/D external clocks https://forum.amsat-dl.org/index.php?th ... /&pageNo=2

Tom has written a guide here https://www.zr6tg.co.za/2022/06/28/adal ... -for-datv/

Mike

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g6hfs
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Re: Pluto external clock input

Post by g6hfs » Fri Jan 20, 2023 3:28 pm

Hi Mike,

I will try your suggestions thank, as a note I found this:

#fw_setenv refclk_source external // Change to external reference clock
I still had problems with the settings that after a power cycle was reset to defaults again, but here is the solution:
#fw_setenv qspiboot_extraenv true // This will preserve the settings still after a power off

Will try this when I next have a try.

Thanks

Brian

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