Yet another DIY GPSDO - yes, another one

[felixd]

Hey Bob, YES! now You need to wire up the board. Few changes in code and GOOD wiring and we have working project!

I just went trough that. you can do it.

Yellow trace is 10MHz from OCXO.
Blue same signal, after resistor

[iannez]

Hi bob91343,
If you have a breadboard and jumper cables you can enter the components
and make connections to test both the micro and your GPS (what model is it?).

I attach some photos and AndrewBNC schematic that have already been posted.
These make you understand how to make connections to the various micro pins.


I also put a picture of you like I do the tests, but don't look at the cables or anything
because I use for now in the absence of VXCO another oscillator.

bye, A.

[felixd]

Some more images of my setup. BTW, that's not my lab but since my wife is gone for some days... hahaha I moved some things to different place.

Below some log from AutoCalibration  I run after GPSDO was running for about 40 minutes. I was checking frequency range avail for correction.

Code: [Select]

UTC Time: 19:46:29 Date: 27/1/2022

Voltages:
Vctl: 0.33  DAC: 2406
VctlPWM: 1.91  PWM: 37889
Vcc: 5.00
Vdd: 3.31

Frequency measurements using 64-bit counter:
64-bit Counter: 34517460710
Frequency: 10000000 Hz
10s Frequency Avg: 10000000.1 Hz
100s Frequency Avg: 10000000.09 Hz
1,000s Frequency Avg: 10000000.016 Hz
10,000s Frequency Avg: 0.0000 Hz

Auto-calibration sequence started

Calibrating...
set PWM 1.5V, wait 15s
f1 (average frequency for 1.5V Vctl): 9999997.3 Hz
set PWM 2.5V, wait 15s
f2 (average frequency for 2.5V Vctl): 10000005.3 Hz
Calculated PWM: 37631

Calibration done.


[Badwater]

Any good advice how to enter stm32f411 flash mode via direct USB connection?
I found different procedures for boot and nrst button but I need some 10-20 tries, even it is directly connected to the PC without any hub.

@felixd: your 2nd snap: there is a small bug in display sub routine, between longitude/latitude and voltages the previous text is not removed.

[felixd]

Hey Badwater.

I had same issues on my side (also same issue happened when I was playing with Bobs computer). What worked for me and for Bob was to:

1. Disconnect USB cable from uC
2. Hold BOOT button
3. While holding it plug USB cable.
4. Look for STM32 BOOTLOADER device in Device Manager

If it won't work try to install STM32 Cube Programmer software first and follow above steps again.

https://www.st.com/en/development-tools/stm32cubeprog.html

That worked for me and Bob.
Once STM32 BOOTLOADER driver is loaded correctly You can than (while USB cable is connected) just press and hold BOOT button and press shortly NRST. Now it should work just fine.

Tell me please if that helped.

Cheers, Paweł.

[felixd]

@felixd: your 2nd snap: there is a small bug in display sub routine, between longitude/latitude and voltages the previous text is not removed.

You're spying on me! haha ;]

Yes, I have noticed that. I am using not modified source code from Andrews GitHub. It's not a big deal at the moment. Most important if frequency

I am trying to reorganize this repo a little bit. You can check for changes I have made here: https://github.com/felixd/STM32-GPSDO/tree/main

BTW, I am using u-Blox NEO-6M, works a treat (8M is on the way).

[Badwater]

You're spying on me! haha ;]

  ... no, no ... I noticed the same here and fixed it for me. I am not acquainted with the git stuff, neither a good programmer 

[iannez]

I use a stlink for programming blackpill.


and usb connector for debug with arduino ide.

Simple and comfortable.

in the photo bluepill but it s the same for blackpill

[AndrewBCN]

...
@felixd: your 2nd snap: there is a small bug in display sub routine, between longitude/latitude and voltages the previous text is not removed.

Yes, there is a small bug, it's missing a line that clears the display. That should be fixed in my next release, or you can add the line.

[Badwater]

I use a stlink for programming blackpill.

Yes, this works flawlessly ....

The advice from @felixd is also not always working, my two (chinese) boards are picky 

Tnx, Frank

[felixd]

...
@felixd: your 2nd snap: there is a small bug in display sub routine, between longitude/latitude and voltages the previous text is not removed.

Yes, there is a small bug, it's missing a line that clears the display. That should be fixed in my next release, or you can add the line.

Hey Andrew, fix has just been added to #4 pull request on GitHub. I have also added some more information to be displayed on OLED during calibration.

[bob91343]

This whole conversation is way over my head.  Does it mean I have to reload the pill?

[felixd]

Yes, Bob.

We will have to make small changes in software, re-compile it so we will have new firmware that we can upload to a hardware.

I will help You with that.

We will prepare Minimal Version that doesn't requier by You to have: OLED nor other sensors. Just:
- STM32 μC - BlackPill
- OXCO
- resistors and capacitors + some cables. (analog things )

I never asked, which components have You already bought Bob?

-----
@AndrewBNC

First time GPSDO is running longer than 8 hours:

Code: [Select]

Sats: 11 HDOP: 0.90
UTC Time: 06:16:47 Date: 28/1/2022

Voltages:
Vctl: 0.34  DAC: 2406
VctlPWM: 1.93  PWM: 37855
Vcc: 5.00
Vdd: 3.31

Frequency measurements using 64-bit counter:
64-bit Counter: 277404315810
Frequency: 10000000 Hz
10s Frequency Avg: 10000000.0 Hz
100s Frequency Avg: 10000000.00 Hz
1,000s Frequency Avg: 10000000.000 Hz
10,000s Frequency Avg: 10000000.0001 Hz

Nice!

[AndrewBCN]

...
@AndrewBNC

First time GPSDO is running longer than 8 hours:

Code: [Select]

Sats: 11 HDOP: 0.90
UTC Time: 06:16:47 Date: 28/1/2022

Voltages:
Vctl: 0.34  DAC: 2406
VctlPWM: 1.93  PWM: 37855
Vcc: 5.00
Vdd: 3.31

Frequency measurements using 64-bit counter:
64-bit Counter: 277404315810
Frequency: 10000000 Hz
10s Frequency Avg: 10000000.0 Hz
100s Frequency Avg: 10000000.00 Hz
1,000s Frequency Avg: 10000000.000 Hz
10,000s Frequency Avg: 10000000.0001 Hz

Nice!

Well done!  Thanks for all the feedback and GitHub contributions!

And with 11 sats tracked, the measured precision is similar to what I get, and exceeds the project's original target precision by two orders of magnitude! So really not bad for such an inexpensive GPSDO.

[felixd]

Well done!  Thanks for all the feedback and GitHub contributions!

And with 11 sats tracked, the measured precision is similar to what I get, and exceeds the project's original target precision by two orders of magnitude! So really not bad for such an inexpensive GPSDO.

Thank You. That's correct, it was not expensive.

Paweł.

[iannez]

Hi Felixd,
I saw that you talked about github and there would be a bit of things in the default code they don't compile.
 if for example I comment The DAC 12bit #define...

How can you proceed?

tnx, A.

[felixd]

I don't understand Your question correctly. Can You write it ance again?

https://github.com/felixd/STM32-GPSDO <-- this is my fork of AndrewBCN repository. I am making my own changes there + I am pulling my main branch to Andrews main branch (but he needs to accept changes first).

And if You are intersted in changes I am trying to pull to Andrews GitHub repository:
https://github.com/AndrewBCN/STM32-GPSDO/pull/4/files

If by DAC 12-bit commenting You mean this line:

Code: [Select]

//#define GPSDO_MCP4725         // MCP4725 I2C 12-bit DAC
https://github.com/felixd/STM32-GPSDO/blob/main/software/GPSDO/GPSDO.ino#L126

Yes, that has been fixed on my side.

That's the quick fix: https://github.com/felixd/STM32-GPSDO/commit/6075b9ca35ba59c5528f45c6956bfe042e1bc88a

Cheers

[iannez]

I understood now.

You made a fork on github where locally make your changes.

I have to study github

bye, A.

[felixd]

I understood now.

You made a fork on github where locally make your changes.

I have to study github

bye, A.

Yes, study Git (Github is just an "overlay" on Git).

https://lab.github.com/githubtraining/introduction-to-github

Some YT videos on topic:

[iannez]

Yes one step at a time

https://github.com/iannezsp/STM32-GPSDO

next step i try pull request, i hope

A.

[bob91343]

I bought boards at All Electronics.  Now to assemble the project.  Maybe I have all the parts.

[felixd]

I bought boards at All Electronics.  Now to assemble the project.  Maybe I have all the parts.

Remember, less parts, less problems 

[bob91343]

So no parts, no problems?

[felixd]

100% TRUE 

But I guess we need "a little problem". Everything is wired up already?

[bob91343]

Not yet.  I had to install a security light and camera outside.  Now I need to warm up and maybe practice some jazz.  I have to be in the right mood for these things.

I did in fact do some work on an LCD illuminator for a DMM.  Once I take inventory of the parts I will decide how to organize the hardware.  I don't know if I should use perf board or a push-wires-in breadboard I bought.  I need to mount the black pill, the arduino, the receiver, the TCXO, and I have to see what else.  I spent about $5 for stuff from All Electronics.

The layout needs to allow for connections to power, antenna, and output connector.  The operation of this gizmo is still a mystery.