Why are most designs using the wrong TCXO/OSC Pin?

MMDVM_HS Hat hardware
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2W0ODS
Posts: 2
Joined: Tue Dec 08, 2020 10:37 am

Why are most designs using the wrong TCXO/OSC Pin?

Post by 2W0ODS »

Looking at several Simplex and Duplex MMDVM “HS Hat’s” I have here that I’m going to change the TCXO to a higher quality part.
I noticed that ALL my boards (Of all different designs) have the TCXO output going to the OSC1 Pin on the ADF7021, but that pin is for using a 0.8V Clipped Sine TCXO output, OSC2 is for a HCMOS/CMOS TCXO with 3V or higher output and all the published schematics and parts lists all list a part number for a TCXO with a 3V or higher (80% of VDD usually) output.

Just curious to why this has been overlooked? Surely to get the most of a high quality TCXO you would use the correct pin on the ADF7021 and disable the internal OSC.
KE7FNS
Pi-Star Team
Posts: 1823
Joined: Wed Apr 17, 2019 11:11 pm

Re: Why are most designs using the wrong TCXO/OSC Pin?

Post by KE7FNS »

2W0ODS wrote: Tue May 11, 2021 9:26 am Just curious to why this has been overlooked?
I don't think you are going to get any answers from any board developers. Pi-star is the software run on the RPi, not the hardware design of a MMDVM_HS hat.
If someones previous actions are any indication of their future actions, then I predict the deletion and removal of access will happen at any moment. 7-11-2020.

"07/13/20 This Website Has Been Taken Down" ... again :lol:
2W0ODS
Posts: 2
Joined: Tue Dec 08, 2020 10:37 am

Re: Why are most designs using the wrong TCXO/OSC Pin?

Post by 2W0ODS »

Does anyone know here where the register R1_DB12 is set high or low, is it in the firmware or MMDVM host and what is it set at by default?

Many thanks.
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G8SEZ
Posts: 431
Joined: Fri Apr 13, 2018 8:26 pm

Re: Why are most designs using the wrong TCXO/OSC Pin?

Post by G8SEZ »

2W0ODS wrote: Thu May 13, 2021 8:42 am Does anyone know here where the register R1_DB12 is set high or low, is it in the firmware or MMDVM host and what is it set at by default?

Many thanks.
It will be in the firmware, it's available at github

https://github.com/juribeparada

so you should be able to find how that register bit is set by reading the code.
--

Brian G8SEZ
KE7FNS
Pi-Star Team
Posts: 1823
Joined: Wed Apr 17, 2019 11:11 pm

Re: Why are most designs using the wrong TCXO/OSC Pin?

Post by KE7FNS »

2W0ODS wrote: Thu May 13, 2021 8:42 am Does anyone know here where the register R1_DB12 is set high or low, is it in the firmware or MMDVM host and what is it set at by default?
Again, the vast majority of people viewing this forum are not board designers and have zero knowledge of how the code functions.
If someones previous actions are any indication of their future actions, then I predict the deletion and removal of access will happen at any moment. 7-11-2020.

"07/13/20 This Website Has Been Taken Down" ... again :lol:
KE7FNS
Pi-Star Team
Posts: 1823
Joined: Wed Apr 17, 2019 11:11 pm

Re: Why are most designs using the wrong TCXO/OSC Pin?

Post by KE7FNS »

Contact the actual MMDVM/MMDVM_HS developers via github and ask them, they will at least be able to provide the most knowledgeable answers. rather than responses like that.

I tried to let this slide but its just going to wind up with all kinds of misinformation until someone who actually understands the code responds, which I don't think that they bother to browse a forum that has nothing to do with MMDVM_HS coding.
If someones previous actions are any indication of their future actions, then I predict the deletion and removal of access will happen at any moment. 7-11-2020.

"07/13/20 This Website Has Been Taken Down" ... again :lol:
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