A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

[NivagSwerdna]

If you have a fancy modern PC with only USB then you need a eBay auction: #262312697328 USB to old fashioned RS232 DB9 flavour serial.

You will need 3 wires... GND, RX and TX.

If it is a male DB9 connector on the adapter then... GND is top far right (pin 5) and RX/TX are pins 2 and 3 (can't remember which way around)

[davebb]

Those USB to 232 converters work very well , or you could go Bluetooth
Dave

[Nuno_pt]

I was asking because if the one that I've will do it, I can start debugging, if not will have to order one.

From what I can see my board has on the sides, all the marks need for RS-232.
 

[NivagSwerdna]

Simple Answer: Get a RS232 level interface
Medium Answer: Get a RS232/TTL converter like this... eBay auction: #401099454734 and use your existing gadget
Complex answer: You could remove the SP3232E and interface at TTL levels

My solution interfaces at TTL level to snoop on the TX from the GPS and I interact with the main part of the board at RS232 levels using a level converter.
I didn't want to unnecessarily modify the UCCM-P so I use the headers.

[Bryan]

...

Any luck in the author able to post the changes (source, changes), checked the site and didn't see anything new.

Yes, code has been merged, unified version should be release sooner or later.

Great, will keep an eye out for it.

[Nuno_pt]

Today I've taken the RS-232 PC from another division of the house and bring it to the bench.

I've try first the loopback on the RS-232 by shunting pins 2 & 3 together, using Putty I set it to use COM1 9600 8N1 Xon&Xoff.
Loopback works great, what I type on the keyboard appears on Putty.
So I attach one RS-232 cable straight, female on the PC side and male on the GPS side.
From the GPS pins I use cables from the arduino *female to female* to plug into the cable male connector.
I've start Putty, when typing * ? * the same character appears on Putty, so the Loopback is working.
If I change the RX and TX on the GPS pins, nothing happens.   
Also if I connect pin 5 to pin 5, that is GND, there is no caracter on the screen only garbage.

Anyone have some test that I can do, or more ideas how I can try it to see if I get something out of the GPS.

I can put screen shot's.

[davebb]

Hi you need to change your baud rate to 57600 8N1 no flow
control
Dave

[davebb]

Hi 9600baud is just for the GPS module  and that is at TTL
Level
Dave

[Nuno_pt]

Hi Dave,

Thanks for the replay, I'll try 57600 tomorrow, I see that I'm using " Xon/Xoff ", and should be using " None " instead.

Yes the TTL levels from the Furuno itself work very well at 9600 8N1 Xon/Xoff with and TTL to Mini USB adapter.

I'll report here the same experience but at 56700 8N1 None

[NivagSwerdna]

57600-8-N-1

From my male USB to serial adapter....

Looking into the pins with the 5 pins in top row, 4 pins in lower row, top row, Pin 1 on left, Pin 5 on right

Pin 2 ------------ Blue Wire   --------------------------  TX
Pin 3 ------------ Pink Wire   ---------------------------RX
         ----------  Not connected ------------------------  BT
Pin 5 ------------ Green Wire  ------------------------- GD

Flow control None (but XON/XOFF will also work)

You do need to get the device started... with my dodgy power supply I have to wait for 10 mins until the OCXO is warm before it resets fully and LEDs flicker etc.

Once started you should see...

Code: [Select]

Symmetricom Boot Code ver. 1.01.01


Press Enter to go to boot
Image1: [1.0.0.2] [454535 bytes] [valid checksum:0x20AFA24] [timestamp:3]
Image2: [1.0.0.1] [454535 bytes] [valid checksum:0x2142B89] [timestamp:2]

Loading Image1
UCCM-P >


[Nuno_pt]

Thanks NivagSwerdna,

I can't open my cable, the DB9's are sealed.
But I extend the output of the male connector with female to female dupon cables from arduino, one side to the DB9 male pins the other side to the GPS pins.
I was using 9600 8N1 XON/XOFF, let's see if it works tomorrow.
If not maybe I've to send the board back.

[Nuno_pt]

Mine is plug almost all day, power supply here is not a problem, it's on 5V but it has 35A, so no problem with current to the OCXO.

I've check all the voltages on the test points, all of them are spot on, the OCXO will be hot, the led's work, so no problem to plug it in and leave it alone for 10 or 20 minutes to see that code.

That code appears by itself, after you connect successful at the COM port, but without typing anything on Putty, correct?

I still don't have the GPS antenna, it's on order, also the RS-232 to TTL, SMA connectors, MCX to SMA cables, and for display I want to see if a friend of mine want's to donate one of is 3.2'' TFT.
Raspberry 3 is also on order to make a Stratum 1, and I'm looking at G4HUP 10MHz distribution amplifier.

This will be put in one box, to feed the lab with 10MHz.

If all work well, another one with only 10MHz will follow for the Ham station to plug the transverter's and radios.

[NivagSwerdna]

I can't open my cable, the DB9's are sealed.

The cable colours were just my patch leads, nothing clever intended.  No opening of any cables.
Incidentally, I have taken to powering mine with 6v (which is above max for the onboard boost converter) but I need some headroom over 5v for the mega2560 regulator, it hasn't blown up yet.
re: communications.... you get the bootup message at board reset.  (You can get this to happen by pressing RST), otherwise you need to send a command e.g. "?"

[Bryan]

Hi Dave,

Thanks for the replay, I'll try 57600 tomorrow, I see that I'm using " Xon/Xoff ", and should be using " None " instead.

Yes the TTL levels from the Furuno itself work very well at 9600 8N1 Xon/Xoff with and TTL to Mini USB adapter.

I'll report here the same experience but at 56700 8N1 None

You can also adjust the RS232 header to a different baud rate by using one of the two and select your baud rate.

SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600
or
SYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600

I think it's the second one.

Just a note your settings won't stick after a reboot, although I think the following may store the setting, just never tried it

SYSTem:COMMunication:SERial1:PRESet
SYSTem:COMMunication:SERial2:PRESet

[Nuno_pt]

Morning all,

It's working, I can issue commands, and get replays.

I issue the STATUS command, and get the following, see attach.

The PC doesn't have internet there, waiting for the WiFi USB pen's, so can't paste the code directly here.

The #Operation Alarm is ok, since I don't have yet the antenna connected, but the rest is ok, I suppose.
If I issue an ALARm:OPERation? It returns Antenna fail, because there is no antenna connected yet.
If I issue an OUTPut:STATe, it returns UNLOCK.

If you want that I issue other commands to see if the board is ok, just let me know.

Update:
BOM order:
Arduino Mega - http://www.ebay.com/itm/400935362320?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
GPS Antenna - http://www.ebay.com/itm/261953407322?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
SMA 90º connector - http://www.ebay.com/itm/271265210952?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
MCX to SMA cable - http://www.ebay.com/itm/281108847224?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
RS-232 to TTL converters - http://www.ebay.com/itm/400461786687?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Next order will be:
TFT 3.2" - http://www.ebay.com/itm/3-2-inch-TFT-LCD-module-Display-with-touch-panel-SD-card-240x320-touch-pen-beu-/182070719728?hash=item2a6442b4f0:g:TQEAAOSw0vBUj-1t

Raspberry 3 - For NTP Server (Stratum 1)

[NivagSwerdna]

I think I'm almost done... Just got to split my 10MHz two ways and then I can get on with my original project!

I wired the LEDs on the UCCM-P to digital inputs,  on the front panel I have 4 dual colour (RED/GREEN) LEDs that are then driven by the microcontroller.  Currently it is just passed through but I think I might change the logic as the rapid green flashing is a bit annoying, think I might make that a stable Green.

[Nuno_pt]

Very well, I like it, big thumbs up.
 
Where do you pick the led's?
On the resistores or on the Led´s.
Can you take a picture of it?

Between the TFT and the Mega is that a shield for the TFT?

Can you show the connections to the Pi, I got here 2 Pi2, don't know if I use this or order one Pi3.

For mine I'll use one kit of 8 exit's on 10MHz from G4HUP.

I want to have all here to chose the box type, to accommodate all, GPSDO, Rasp, 10MHz amp.

[NivagSwerdna]

These are my connections on the bottom of the board.  (Horrible... this was my first attempt it's much neater now)...

As per... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg909870/#msg909870

Connections are on driven side of the LEDs (i.e. opposite side to resistor).  I left the board LEDs in place.

[Nuno_pt]

Thanks for the photos, I've some work for tomorrow, the GPS hack I've it too but I don't think that I've those pins there, Pin 3 is ok, but Pin 5 I don't think I've that one tap.

Is the Rasp picking the 1PPS pulse ok?
Seems some complains about it be too short 10uS or so, and the Rasp can't get it, so some use 74AC to increase it to 225 to 250uSe

[NivagSwerdna]

I use the GPS PPS not the UCCM-P.  It is plenty wide enough.  I wasn't worried about operating in holdover mode. (Also the GPS pulse is synchronised to UTC, no idea what the guarantees of the UCCM-P PPS pulse are other than being 1Hz)

[Nuno_pt]

I only saw that you're using the Furuno PPS NMEA sentence after writing the replay.
Yes the only advantage of taking the PPS of the MCX is the 1Hz, the circuit of the PPS taken out of the MCX is very simple so I might try it and see what I get.
It's just taking the 1PPS from the MCX feed it to an 74AC and create an divider, two outputs and another to the Raspberry.

[NivagSwerdna]

I use the PPS signal from the GPS module for the PPS for NTPd, this is 500ms on/500ms off, with the rising edge being synchronised to UTC.  (I also used the NMEA $PFEC,GPtps message from the GPS TX pin for the NMEA reference clock for raw time).

I compared the PPS from the UCCM-P with the GPS and I guess it is not surprising that they are in phase (after all this is the driver for the discipline of the LO).  So it makes no difference which you use for the NTPd.  The advantage of the UCCM-P being it continues, with disciplined OCXO accuracy, during holdover whereas the GPS module has only its local oscillator to remain in sync.

UCCM-P is 50us width probably best stretched to 20ms or so if using for Pi GPIO.

I tried using a pulse stretcher circuit (attached), introduces around 1us delay, stretches to just over 20ms with a 82k and 0.1uF.  Not sure which signal I will use now!

Attached a couple of screenshots.

[GI1CET]

Got one of these and i have been reasonably lucky but..

GPS fine
OCXO fine but not being disciplined and the only damage I can find is a missing U26 and a displaced cap
Anyone know what U26 should be?

Thanks in advance
Jim

[davebb]

Hi is it just me but your board looks all black And burnt
Dave 2E0DMB

[PA0PBZ]

This is U26, not sure what it is: