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On Fri, Nov 1, 2019 at 01:55 PM, Rich NE1EE wrote:

I was thinking yesterday that the ST would present a very high impedance on
VBAT when a) the unit is running, so VBAT is internally switched off, and b)
VBATEN is off, so the bridge is not in the loop.

When the VBATEN bit is set the bridge divider is enabled and the input impedance of the VBAT pin will be 100kOhm.

When the VBATEN bit is unset Table 32 of the data sheet indicates that IDD_VBAT (the RTC domain supply current) is only ~1.3uA at 3.6V and 25degC. So the input impedance will be ~2.8MOhm.

The DMMs I have here have too low an impedance to measure VBAT, accurately, at least when VBATEN is unset.

The only way I could make anything like a reliable measurement was with a 'scope and a x10 10MOhm probe. You can easily see when VBATEN is set or unset per Raymond's excellent pictures.

Let's assume we are using a silicon diode for D2.

When VBATEN is set the diode current will be ~40uA and Vf ~0.45V. If the maximum charge voltage of the battery is 4.2V then VBAT will not go above 3.75V which is within the 4.0V maximum.

But when VBATEN is unset the diode current will only be ~1.5uA and Vf ~0.25V. So VBAT could reach 3.95V which is very close to the 4.0V maximum. In fact I measured 4.00V on the 'scope this afternoon with a single silicon diode as the battery approached full charge.

I previously installed a single SOD323 diode marked A6. Today I made some measurements of the battery voltage using that diode with a 'scope, and was consistently seeing Vf ~0.25V when VBATEN was unset i.e. most of the time.

(I now believe this diode to be a BAS316 silicon type, not a Schottky as I previously thought.)

I replaced the BAS316 with half a BAV99 in a SOT23 package marked A7p with identical results i.e. Vf ~0.25V (which kinda confirms the BAS316 theory).

CONCLUSIONS

I do not think a single silicon diode is adequate to protect the STM32 under all charge conditions. So I turned the package through 90deg and reconnected the BAV99 with both diodes in series, from pin 1 to pin2 to VBAT. This drops about 0.5V and allows for a 0.25V margin on the VBAT maximum voltage limit. Pin 3 on the right hand side of the picture is not connected.

When the battery is fully charged QRP's NanoVNA-Q firmware now shows VBAT = 3635mV, which is only a whisker above the 3.6V maximum input to the ADC.

I am not convinced that a diode is the best way to fix this. A diode gives an *offset* which is fine for VBAT protection. But for VBAT measurement a simple voltage divider at the VBAT input could be used to *scale* the battery voltage to the ADC input voltage.

Perhaps if VBATEN was set all the time in the firmware a single 16k resistor at VBAT input (instead of D2) might suffice.

The VBAT current would of course be higher at ~40uA but with a 450mAh battery that wouldn't be too much of a problem.

Nah - not going to work. You cannot be sure the needle has actually caused one layer to blend into another.?

Get an old soldering tip and heat-fuse the layers in a number of areas although I'm not sure the internal structure of the material is conductive.

Or... I've attached a photo of black antistatic conductive foam.If you have any, place something like food wrap (discharge it!) between the foam and your board as the foam conducts.I show 24K ohm and the probes are just laying on top. If I compress, the resistance goes down to 4-5K.



On Friday, November 1, 2019, 12:13:14 p.m. GMT-4, Oristo <ormpoa@...> wrote:

> You're probably making a big capacitor by stacking the sheets with the

adhesive layer between each.

This motivated pinning stacks together; no joy..

The attached script assumes calibration stimulations matching scan ranges
for roughly equal samples per frequency decade.

You're probably making a big capacitor by stacking the sheets with the
adhesive layer between each.

This motivated pinning stacks together; no joy..

The attached script assumes calibration stimulations matching scan ranges
for roughly equal samples per frequency decade.

I have two older Android Phones, (Galaxy S III,
needs battery, and Galaxy S5). Free if you come
and get them.
I am in Vail, Arizona (20m SSE of Tucson).

73, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of Larry Rothman <nlroth@...>
Sent: Friday, November 1, 2019 7:25 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Measuring swr

Or - have a look at the XDA forums for a new ROM:


On Friday, November 1, 2019, 10:17:16 a.m. GMT-4, Michael Dooley via Groups.Io <msdooley@...> wrote:

I bought my samsung galaxy note 3 a couple years ago to experiment on. At the time I had an iphone and the space debris (and satellite) tracking software I wanted to use was (and still is) only available for android.
I did not buy it as a phone, but as an android device. It cost me $15.00.

So instead of using your current phone, check with your friends and see if they will sell (or give) you their old android device to play with!
Mike de N5BGZ

On Friday, November 1, 2019, 03:21:15 AM CDT, Oristo <ormpoa@...> wrote:

> Pretty much the only way around it is to root your phone and install a 7.0 or

higher rom from XDA or one of the other sites that offer un-official upgrades.

.. or rebuild the app, specifying support for older Androids.
Build tools warns about most dependency issues.

Bruce,?
According to the IP5303 chip spec, it has an adaptive charge control and overcharge protection.

/g/nanovna-users/message/4298?
My experience with these chips is that they charge at a low rate - the 1.2A is the inverter output, not the charge current.
I charged an 1100mAH cellphone battery that I originally stuck on my 1st Nano - no issues but it took a long time to charge - but boy, did it ever have a long runtime.
...Larry

Hi Joe,This was done on the 1st (White Gecko) Nano I purchased (it had no shielding).I found it improved the noise level slightly (visually on the display) from what it was before, but I never really took any quantifiable measurements at the time.Sorry.

Lithium batteries are designed to be charged at a somewhat constant rate. Chargers are designed to limit that rate to whatever is safe for a battery. The charger in the nanoVNA is probably designed to deliver the current need to charge the 500 mah battery and no more. A larger capacity battery will require more charge time but there should be no issue with charging it with the built in charger. Just don't try to substitute a battery with higher voltage. You will destroy the battery and the charger.

Bruce, K4TQL

I know that many developers protect their work from deliberate claims of prior ownership. But, I suspect that many do not. There are three types of protection: copyright, patent, and trademark. Two of these, patents and trademarks, need to be registered to provide protection. Copyrights do not. A copyright will protect even if you don't register it. Registration will determine if you are truly the original author.

If I were a developer or author, I would at least copyright my work. It's easy to do. You just place a copyright mark on your work so that it can be obviously seen. If you want more protection, mail a copy of your work to yourself and keep it sealed. The postmark will give an indication of the date it was created. This is also good practice for patents and trademarks if you need to prove precedence of your work.

This link will tell you what protections copyrights give:

Check it out.

Bruce, K4TQL

Larry,
I see in the picture you posted the other day
/g/nanovna-users/attachment/223/0/Battery-PCB-MiscShields.jpg
that you have added extra shielding. I have a couple of questions on that. Did the shielding help the noise level? And also how do you measure the noise level?
I'm new at this and as far as I know the thing to do is to look at the LOGMAG trace with the corresponding port open and note how much the trace wiggles. Ideally the trace would be 1 at all frequencies since all energy is always reflected.

Or - have a look at the XDA forums for a new ROM:?

I bought my samsung galaxy note 3 a couple years ago to experiment on.? At the time I had an iphone and the space debris (and satellite) tracking software I wanted to use was (and still is) only available for android.? ?
I did not buy it as a phone, but as an android device.? It cost me $15.00.

So instead of using your current phone, check with your friends and see if they will sell (or give) you their old android device to play with!
Mike de N5BGZ

On Friday, November 1, 2019, 03:21:15 AM CDT, Oristo <ormpoa@...> wrote:

> Pretty much the only way around it is to root your phone and install a 7.0 or

higher rom from XDA or one of the other sites that offer un-official upgrades.

.. or rebuild the app, specifying support for older Androids.
Build tools warns about most dependency issues.

On Thu, Oct 31, 2019 at 09:23 PM, QRP RX wrote:

@edy555 and @hugen79 firmware takes 2 measurements (1 VBAT + 1 VREF).
NanoVNA-Q takes 64 measurements with average filter (32 VBAT + 32 VREF) with a
total measurement time about 1.24 ms (620.5 us + 620.5 us).

The filter was added, because 1 measurement is too noisy

So I see that much has been revealed by all of you while I slept! I awoke to new issues with a large project that I am beta testing, and got completely caught up in it.
A few quick comments before I dash.
I was thinking yesterday that the ST would present a very high impedance on VBAT when a) the unit is running, so VBAT is internally switched off, and b) VBATEN is off, so the bridge is not in the loop. I don't think that VBAT can source current, but I also don't know if its input is clamped low, even by a high impedance.
But this possibly explains why the measurement is noisy.
In the first place, BATT is not sourced by an isolated coin battery, but by a battery that is getting charged by a device that has some amount of ripple, however small.
And in addition, there is likely a 'startup' time from the time that VBATEN is toggled on to when the line settles.
32 samples seems like a lot, though...I'd have thought that after some settling time that 1-4 samples should be plenty.

So this is a good time to mention that I have embedded software and hardware dev experience, but I don't think that I know as much about this device, or even some of the specific issues we are addressing, as some of the others here.

For example, how do diodes behave at very low currents? Never had to think about it, but 40 uA is pretty small.
Can you share the data gathered during one battery sampling period? VBAT and VREF.(really VREFINT?) Please also share the sampling sequence...
When is VBATEN turned on and off? Is it for the whole time of 32 samples?
How does the hardware respond to ADC requests for samples?

STM32F072CBT6 ST RM0091 Reference manual DM00031936.pdf
13.4.5 Channel selection (CHSEL, SCANDIR)
The internal voltage reference VREFINT is connected to channel ADC_IN17. The VBAT channel is connected to channel ADC_IN18.

The manual has some discussion of settling time that I have not reviewed.
13.4.6 Programmable sampling time (SMP)
Which could possibly contribute to reducing the need for 32 samples.

I can see why the concern for removing the bridge when VBAT is supplied with something like a coin battery. But we have this honkin' big 450mAh+ battery. A test might be to put a high ohm resistor to ground from D2-, resulting in some sort of steady-state (SS) current flow. I realize that the bridge is already 100k. But the battery can source all the current that both circuits can consume.

I am under the impression that we concluded that Mike is seeing 4V+ at D2- because our DMMs have a slow response time, and the voltage dip during sampling is only 1 ms wide. And once the sampling begins, the diode drops the voltage at D2- just as we suppose it should, so the VBAT is not at risk.

Gotta dash...
73
--
On the banks of the Piscataqua
Rich NE1EE

The 'nosys" versions do not work - don't fully boot - just the 2 freqs along the bottom of the display

Thanks but what versions would they be equivalent to?Is the QRP build like 0.4.2 or 0.4.3 with the new options and fixes?And the other 2 builds - 0.3.2 or ??

...Larry

FYI.
Here is latest NanoVNA and NanoVNA-Q
-Branch_commit#.[bin/hex/dfu]
-Name with "_Os_nosys" changed compile/linker options
-I don't have those hardware, Please inform to me it works or not-

After flashing, I highly recommend to reset all configurations: "clearconfig 1234", then "reset"

Wow a lot of good information found. A seemingly simple thing like a battery indicator isn't so simple after all. :-O

The problem with shutting down the inverter is you lose the +5 for the 612's.
So - it may be more prudent to use a 2S battery (7.2V) and go through an LDO 5V linear reg and forget the 5303 altogether.
You can kludge something together that still charges the battery by using a separate 2S charger:


Stick it all in a printed housing along with N connectors and you'll have a nice device.
...Larry

The forum admin enabled hashtags a few weeks ago so you can add your own unique hashtag to every message you post??
- or -??
click on the subscription link on the left margin and then Group Profile link - you should see the option to display all your posts.

#69 : combined fortran, maxima and gnuplot code for [errors in "error" models]
-
references:
Jose Luu - 3 October 2019 : /g/nanovna-users/message/3812
Gary O'Neil - 17 October 2019 : /g/nanovna-users/message/5075
#60 - 20 October 2019 : /g/nanovna-users/message/5312

Hello,

Allow us, please, to inform you that we are in the process of revising and updating
our combined code for [errors in "error" models], so we are still staying far behind
of the replies we owe regarding the specific questions about our work
-
please accept our apologies.

Also, allow us, please, to inform you that during this process we need to tediously
look in various volumes of those nineteen 19 consisting the huge accompanying
documentation of [open watcom 2.0] (2017), so we thought to concentrate them,
by using the current version 9.5 of the free [pdfShaper]:



in just one very "handy" PDF volume of 6,136 pages, definitely responding to the
[Find] and [Search] capabilities of the free [PDFXchange] viewer:



which we just uploaded to [archive.org] at:



Sincerely,

gin&pez@arg

: 69#

Thanks for your suggestions Rune. I wouldn't put you to the trouble of trying to build an XP machine simply for this.
It is enough that the little Q1 works with NanoVNA Mod3 (as noted by QRP RX elsewhere).

Thanks to the group for all the other suggestions.

Kind regards
Tony