10MHz GPSDO by "BH3SAP"

[daddygo]

Hi @ME,

@fredo_  says that the BP, if not this original GPSDO supplied, -  PCB mod. requires, - as described in previous pages in this thread (3).

The BP will not start correctly from the main PCB TCXO 10MHz clock if these conversions are not done!!!

@ME "The bp resistor value was ok so didnt require swapping,...."
they are not resistors they are capacitors

1. pls. remove C13 and C14 (from new BP) and connect the short wires to the OSCIN pin towards the baseboard
this is the soldering point (PIN) next to the C13 cap, !!! in my picture it is not soldered over because the original quartz is in place, but you better move it..


if you do these, please come back and report back on how it went 

[ME]

So do i leave the wire from the main board still connected to the leg/pin of the bp xtal and completly remove c13+14 from the bp?,  ps i cant find the thread you talk about (3) can you llink it?, thanks.

[daddygo]

yes, remove the two caps C13 and C14, solder the small wire to the OSCIN which is the solder point next to the C13 cap (this is original 8MHz quartz OSCIN PIN to STM32), you don't have to remove the original quartz, it stays on the PCB, but it will be inactive


sorry, -  it's on the fourth page of the thread and my post, top third of the page, it's an old forum software and difficult to give an exact link
https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/75/

[ME]

Thank you removing thos caps cured it.

[ME]

Can the bp still be programed after c13+14 have been removed using st link v2?.

[fredo_]

Hi,
I just released v0.1.8 : https://github.com/fredzo/gpsdo-fw/releases/tag/v0.1.8
Changes :
- Merged potential buffer overrun fixes from 2A03
- Merged Time Zone support from 2A03
- Added 'Model' entry in GPS menu to show detected GPS module
- Added baudrate setting command for ATGM336H GPS module
- Added 'Frame' entry in GPS menu to show first characters of last received GPS frame
- Added 'Date' and 'Date/Time' screens

[ME]

nice work but againe, Can the bp still be programed after c13+14 have been removed using st link v2?.

[fredo_]

nice work but againe, Can the bp still be programed after c13+14 have been removed using st link v2?.

I can't help you here, I never did that mod, but assuming it's the same mod as performed on the original bluepill board, I can confirm that I can reflash the original board with no issue.

[ME]

Heres what happened, I flashed fredo 1.7 to the bp and I would have no display at random, As if the bp was not starting/oscillating everytime on power on, Then i removed c13+14 and it started with a display everytime, I then removed the bp to flash dankar fw to try out, the flash seemed to go ok using stlink or cube programer, However since i did that i am back to no display,i since reflashed the new fredo 1.8 with the same result ie no display,any ideas?.

[fredo_]

Heres what happened, I flashed fredo 1.7 to the bp and I would have no display at random, As if the bp was not starting/oscillating everytime on power on, Then i removed c13+14 and it started with a display everytime, I then removed the bp to flash dankar fw to try out, the flash seemed to go ok using stlink or cube programer, However since i did that i am back to no display,i since reflashed the new fredo 1.8 with the same result ie no display,any ideas?.

Maybe try a full chip erase before flashing ?: https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/msg5838749/#msg5838749

[G4ELJ]

I had that happen once on an earlier firmware.

While still powered up I pressed the reset button on the blue pill board and the firmware then booted up fine and has done ever since.

Duncan

[G4ELJ]

Hi,
I just released v0.1.8 : https://github.com/fredzo/gpsdo-fw/releases/tag/v0.1.8
Changes :
- Merged potential buffer overrun fixes from 2A03
- Merged Time Zone support from 2A03
- Added 'Model' entry in GPS menu to show detected GPS module
- Added baudrate setting command for ATGM336H GPS module
- Added 'Frame' entry in GPS menu to show first characters of last received GPS frame
- Added 'Date' and 'Date/Time' screens

Hi Fredo,

In and running fine on 2 units.

All menus working as you say. Of course over here in the UK I would prefer the date to read 11th March rather than how we read that format as 3rd November .

Many thanks to you, 2A03 and Dankar

[fredo_]

Great, thank you for the feedback @G4ELJ!
Believe me here in France mm/dd/yy was not my first choice either, but I figured I should line-up with "rest" of the world 
Maybe I should add a configuration menu for date format... 

[ME]

Heres what happened, I flashed fredo 1.7 to the bp and I would have no display at random, As if the bp was not starting/oscillating everytime on power on, Then i removed c13+14 and it started with a display everytime, I then removed the bp to flash dankar fw to try out, the flash seemed to go ok using stlink or cube programer, However since i did that i am back to no display,i since reflashed the new fredo 1.8 with the same result ie no display,any ideas?.

Maybe try a full chip erase before flashing ?: https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/msg5838749/#msg5838749

Did that as per instructions with the same result,guess removing the caps 13+14 must kill correct programing?.

[ME]

I forgot to mention i extended the osc wire from the mainboard to the bp to make it easer to fit, Its about 8cm long,could that cause the not running/blank display issue i  have?.

[fredo_]

Here is v0.1.9 : https://github.com/fredzo/gpsdo-fw/releases/tag/v0.1.9
Changes :
- Added date format setting in GPS menu (This on is for you @G4ELJ ;-))
- Added manual GPS model selection (press encoder un GPS/Model menu) in case automatic detection fails (this can happen if baudrate is not set properly)

[G4ELJ]

Heres what happened, I flashed fredo 1.7 to the bp and I would have no display at random, As if the bp was not starting/oscillating everytime on power on, Then i removed c13+14 and it started with a display everytime, I then removed the bp to flash dankar fw to try out, the flash seemed to go ok using stlink or cube programer, However since i did that i am back to no display,i since reflashed the new fredo 1.8 with the same result ie no display,any ideas?.

Maybe try a full chip erase before flashing ?: https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/msg5838749/#msg5838749

Did that as per instructions with the same result,guess removing the caps 13+14 must kill correct programing?.

Removing the capacitors does not affect programming. I have been re-programming up to four modified Blue Pills, which I swap alternately into two GPSDO's, as new firmware comes out without any problems.

I do however keep the wire to the oscillator pad as short as I can.

Duncan

I program and then verify, just to be sure.

[ME]

I wondered if the longer osc wire can cause a slight delay and stop the fw from running?.I made the wire longer with a male+female dupont connector in it so i can change the bp without soldering.

[daddygo]

I wondered if the longer osc wire can cause a slight delay and stop the fw from running?.I made the wire longer with a male+female dupont connector in it so i can change the bp without soldering.

Hi @ME,

sorry, I was away for a few days...

-nope, - removing C13 and C14 does not affect programming
-yes, do NOT lengthen the OSC wire because it will introduce parasitic stuff into the system, it was not so short for nothing 

[daddygo]

Here is v0.1.9 : https://github.com/fredzo/gpsdo-fw/releases/tag/v0.1.9
Changes :
- Added date format setting in GPS menu (This on is for you @G4ELJ ;-))
- Added manual GPS model selection (press encoder un GPS/Model menu) in case automatic detection fails (this can happen if baudrate is not set properly)

Hi @fredo_

thanks for this too...
see, you still have something to add and you'll never close the cover of the box, hihihi 

[ME]

A couple of newby questions 1 is it ok to program the bp with it stil in the mainboard and 2 will the fw run when the bp is fitted and the stlink connected to the bp but not plugged into the pc usb, If that makes sense?.

[daddygo]

1. -YES, -I never take the BP out of the slot during programming, ergo I program it in the base board (what to look out for to avoid starting the GPSDO PSU!)
these are minimally configured BPs for the STM32F103... MCU and have no galvanic isolation or other protection to the PSU(s)

2. - again the answer is yes, to rule out my mistake, I always disconnect the ST-Link 3.3V connector so that if I'm stupid and switch on the main PSU there's no problem

the other 3 cables on the SWD header have no effect on the operation!
as you progress in your electronics knowledge, you will see that you will have paranoid things to protect your electronics and yourself

imagine doing this not with 3.3V DC and with a penny of value BP, but with a motor driver at 230 or 400V with a 1500 dollar electronics, so be paranoid and stay safe!!! 

[ME]

Wel i erased the bp the flashed with fredo v1.9fw also removed the dupont connector and shortened the osc wire, It now works, can someone explaine the gps passthru more and explaine what programs to use with it after using a usb 3.3volt usb converter?, thanks.

[daddygo]

- these GPS modules (defa. in this GPSDO u-blox NEO-6M & ATGM336H) are configurable and you can read data directly from them... f.e. with: u-blox u-center SW:
https://www.u-blox.com/en/product/u-center

these are unicum things, so they do not affect the original purpose of the GPSDO

use a USB to serial converter to access the GPS module directly - this is not necessary in principle, because the MCU will acquire the necessary data itself
there is a pass-through from the GPS module directly to the BP PIN(s) RX/TX from the MCU with unmodified GPS data
(someone asked for this at the beginning of the thread and it was implemented)
- in fixed, never-changing GPS positions, you can configure the GPS module to work with fixed data or change the pulse width of the PPS signal, etc. etc. etc.

in most cases you don't need this 

I have built an impedance matcher/driver (50ohm), to which I added a USB to serial converter, so that it can communicate directly with the GPS module

if you don't use this like me, you can get this GPS RX/TX data on BP PINs to send/receive to your own external USB to serial converter


+++edit:
rather, --- the big lesson now was that at 10MHz (specifically for oscillators) you can't use wires of the length you had in mind 

[ME]

does the ublox u center sw work with ATGM336H gps moduals then?.