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PCB layout questions, not urgent.


Dom Baines M1KTA 2021/02/01 09:11

I have V2.2 in front of me and I've scanned the docs and read a few posts and looked at layouts, gone through a few other groups and posts but I am still trying to work out what a few things might be for.
Assuming the S-A-A-2 is display up, SMA pointing towards you.

1. The 5 SIL header on the right lower PCB, what are these for? Marked CONN303 NC NRST GND SWCLK SWDIO on silk screen. (same on original Nano VNA too) Alternative ICSP?
2. C712 not populated and two through hole present.
3. Underside of PCB on base (right under the USB Mini port) what are the pads marked SWDIO and SWCLK for?
4. Two rather large 4mm(?) through plated holes on lower PCB to one side of the JST connection and the other near top edge. What are/were these for?

Regards,

Dom
M1KTA
73

Dom
M1KTA

Dom Baines M1KTA 2021/02/01 09:43

And what are two holes marked S301 for?

73
Dom
M1KTA

Siegfried Jackstien 2021/02/01 20:23

Am 01.02.2021 um 17:11 schrieb Dom Baines M1KTA via groups.io:
> I have V2.2 in front of me and I've scanned the docs and read a few
> posts and looked at layouts, gone through a few other groups and posts
> but I am still trying to work out what a few things might be for.
> Assuming the S-A-A-2 is display up, SMA pointing towards you.
>
> 1. The 5 SIL header on the right lower PCB, what are these for? Marked
> CONN303 NC NRST GND SWCLK SWDIO on silk screen. (same on original Nano
> VNA too) Alternative ICSP?

when you after soldering the parts on the pcb ... wanna upload anything
to the chips ... it does not work over usb ... so yes that is a
programming port

also if you want to upload a new bootloader (example for upgrading to
"v2"plus") you need that programming port

(sidenote ... for upgrade to plus it does not work with only change fw!!)

> 2. C712 not populated and two through hole present.
you can add a cap there (say 470uf) ... but if it is to big the unit
does not start properly (so using 1000 uf or more does NOT work)
> 3. Underside of PCB on base (right under the USB Mini port) what are
> the pads marked SWDIO and SWCLK for?

programming in factory?? (in fact i have no idea ... but guessing)

> 4. Two rather large 4mm(?) through plated holes on lower PCB to one
> side of the JST connection and the other near top edge. What are/were
> these for?
no idea ...

Dom Baines M1KTA 2021/02/02 01:11

Thanks. Maybe OWO might the S301 as well?

I kinda guessed the two pads under are linked (continuity check) to the pins on the side so maybe in factory programming?

Regards,

Dom
M1KTA

OwO 2021/02/12 01:32

The 5 pin connector on the right is the SWD debug header. C712 is not
populated because it prevents the IP5305 from starting in some cases.
Some clones have C712 populated and you may need to use a USB port that
can source 1A of current. SWDIO and SWCLK is SWD debug interface. The
extra 3mm holes are mounting holes for a smaller LCD.

On 02/02/2021 01:11, Dom Baines M1KTA via groups.io wrote:

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