[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...

Bob Camp kb8tq at n1k.org
Wed Nov 5 20:04:38 EST 2014


There is what could be a programming header on my units. It’s next to the U34 firmware chip. Oddly it does not seem to have a designator on it. There is a similar 10 pin header over by the other firmware chip. That one is not stuffed on my board Ref-0. It’s labeled J101. I *know* what J101 is for - it connects to the GPS. 

If the unlabeled connector is a programming port, it might be there to shoot variable config bits into the board. Yes, it’s more likely to be something like a JTAG port for auto test. 

It’s rare to see a connector like that populated though. Mostly people save the 5 cents and use pogo pins …. Makes you wonder what they used it for. It’s also right by our favorite interface connector….

Three of the pins on the same side as the 1 indication are grounded on the connector. That might suggest that it’s there to plug jumpers onto. They may have had a way to enable this or that to burn in the parts prior to ship.


> On Nov 5, 2014, at 8:01 AM, GandalfG8--- via time-nuts <time-nuts at febo.com> wrote:
> Hi Bob,
> Thanks for the information, I've still just been working from the J8  
> Diagnostic port and it's about time I took a look at the RS422  output.
> The "proper" Ref-1 seems to be working as I'd expect, it's  accepting a 
> valid Ref-0 is present and going into standby as a result.  Pulling out the 
> link cable results in the Standby flashing and inserting  the faker plug at 
> this stage switches it straight to "ON", standby light now  off, and enables 
> the outputs.
> Unfortunately, persuading the other other Ref-1 that it's really a  Ref-0 
> would seem to involve a little bit more than the minor surgery I've  
> performed so far:-)
> Regards
> Nigel
> In a message dated 05/11/2014 12:41:42 GMT Standard Time, kb8tq at n1k.org  
> writes:
> Hi
> On a “real” Ref-0 / Ref-1 combo, the Lucent status  message (RS-422 / PPS 
> port) shows which device the string is coming from. This  is independent of 
> their status bits. Previous digging into similar units shows  the same thing 
> on earlier Lucent GPSDO’s. All the details are buried (200  posts back 
> according to some ..) in one of my previous posts.I do not have  anything on the 
> diag port, so I don’t know what it says. 
> Looking at  the few unknown pins / pairs on the 15 pin connector, I’m 
> guessing that one of  them might be high or low depending on it being a Ref-0 or 
> Ref-1. I’m also  guessing that the pair on pin 15 is serial both ways. At 
> this point my  guessing average is not to good on these parts. I’m not really 
> expecting that  it will improve. Figuring out what the last few pairs do 
> would be a nice  thing. 
> Bob
>> On Nov 5, 2014, at 7:20 AM, GandalfG8--- via  time-nuts 
> <time-nuts at febo.com> wrote:
>> For what it's  worth, here's what happened when I linked two Ref-1 units  
>> together....
>> One was fitted with it's GPS module as normal,  I'll call this Ref-1.
>> The other was as normal other than having it's  GPS module removed, I'll  
>> call this Ref-1-0.
>> The link  cable was around 15 inches long and wired 1-15, 2-14, etc, 
> using   
>> standard 15 way high density plugs.
>> BTW, whereas  shortened pins have been used in the past to ensure safe 
> power 
>> up  sequences I'm pretty sure that on the Z3809A cable it's perhaps a   
>> precaution to reduce the risk of bringing down the base station when  hot 
>> swapping.
>> I've noticed that removing my "faker"  plug once a stand alone Ref-1 is  
> up 
>> and running starts to flash  the Standby light but doesn't otherwise 
> inhibit  
>> operation, the  15MHz and 1PPS outputs remain available. I don't know how 
>> long   this might continue but the system obviously responds differently 
> once   
>> fully booted to when it's first powered and I suspect the use of  
> shortened  
>> pins could be related.
>> Anyway, back  to the two linked....
>> At power up both go through the  flashing light sequence, then...
>> Ref-1-0 -- "No GPS" - Flashing,  "Fault" - Solid
>> Ref-1 ------"No GPS" - Solid, "Fault" - Solid
>> After the boot period finishes.....
>> Ref-1-0 -- "No  GPS" - Flashing, "Fault" - Solid
>> Ref-1 ------"Standby" - Solid, all  other lights off.
>> Both units will talk via the J8 diagnostics  port as soon as powered up 
> but  
>> Ref-1-0 behaves just as one  would expect if the GPS module is removed, 
> and 
>> it  doesn't seem  to be relaying any data from the Ref-1 unit, whilst  
> Ref-1 
>> shows  what looks to be a normal acquisition sequence, the onset of  
>> conditioning, and a self survey
>> At no time is there a 15MHz or 1PPS  output available from either  unit.
>> Although it's been  conjectured that the firmware is identical in the 
> Z3811A 
>> and Z3812A,  and the Prom markings certainly seem to confirm this, it 
> would 
>> also  seem that there must be something that tells the unit what it is,  
>> either by a  firmware difference somewhere after all or perhaps  a link 
> on the 
>> board  somewhere.
>> This isn't just based on  my not very successful experiment, although the 
>> results are no  great surprise:-), but my Ref-1 units always report  
>> themselves  to monitoring software as a "Z3811A Secondary Receiver".
>> Based on this  am I correct in thinking that a standard Ref-0 would 
> report  
>> as  a "Z3812A Primary Receiver"?
>> If so it has to get this information from  somewhere.
>> Regards
>> Nigel
>> In a message dated 04/11/2014  09:38:25 GMT Standard Time,  
>> stewart.cobb at gmail.com  writes:
>> A wiring  diagram of the Z3809A cable  interconnect cable was published
>> earlier on  this list.   That information appears to be incorrect.  The
>> cable  is  actually wired pin 1 to pin 15, pin 2 to pin 14, etc.
>> Another way  to  describe it is that for each wire in the cable, the pin
>> numbers on each end  of the cable add up to 16.
>> A mated  pair of these units is running in my  lab with a scratch-built
>> interconnect cable following the above  rules.  This  scratch-built
>> cable allowed access to the interconnect  signals  while the system was
>> operating happily.  No lights were lit   except the green ON light on
>> the Ref-0 unit (Z3812A, no GPS) and the  yellow  STBY light on the Ref-1
>> unit (Z3911A with GPS  receiver).  The  following signals were observed
>> on the  interconnect (pin numbers given for  the J5 interconnect socket
>> on the Ref-1 unit):
>> Pin 1:  9600  baud serial data  (described below)
>> Pin 2:  logic low   (0.11V)
>> Pin 3:  Ground (0.00V)  Presence detect?  (see  below)
>> Pin 4:  logic high (4.79V)
>> Pin 5:  inverted  Motorola PPS, high (5V) for 800ms, low  for 200ms
>> Pin 6: "17 / 23 dBm"  signal from Ref-0 unit  (see below)
>> Pin 7:  logic high  (4.48V)
>> Pin 8:  Ground (0.00V)
>> Pin 9:  logic  low  (0.11V)
>> Pin 10: "17 / 23 dBm" signal from Ref-1  unit (see  below)
>> Pin 11:  inverted PPS, low 400us,  high (5V)  otherwise
>> Pin 12:  logic low  (0.12V)
>> Pin 13:  Ground  (0.00V)
>> Pin 14:  logic low (0.08V)
>> Pin 15:  logic  high  (4.78V)
>> Pins 3, 8, and 13 appear to be firmly  connected to  Ground.  (Note that
>> these are the three pins  which are clipped short  on the HP
>> interconnect cable.)  On  an unpowered, disconnected box  (either Ref-0
>> or Ref-1), pins 8  and 13 are connected to Ground (low  resistance) and
>> pin 3 is  high impedance.  Presumably pin 3 on each box  (connected to
>> the grounded pin 13 on the other box) is used to sense the  presence  of
>> the other box and/or the interconnect cable.
>> The  timing  of the PPS signal on pin 11 matches precisely the timing  of
>> the PPS signal  available on pins 1 and 6 of J6 (RS422/PPS) on  the
>> active Ref-0 unit.   Presumably this signal is coming  across the cable
>> from the Ref-0  unit.
>> Note:  when the system is coming up from a cold start, SatStat on  the
>> unit with the GPS receiver (Ref-1) will show "[Ext 1PPS valid]" in   the
>> space where it shows "[GPS 1PPS valid]" after the survey is   complete.
>> It appears that the Ref-1 unit timing system is locking  its  oscillator
>> to the PPS coming from the Ref-0 unit during  this  time.
>> The timing of the PPS signal on pin 5  matches the timing of the  PPS
>> output described in the Motorola  OnCore manual.  Presumably  this
>> signal is sourced by the  Ref-1 unit to allow the Ref-0 unit to lock  to
>> GPS.  The  edges of this PPS signal look very dirty compared to  the
>> signal  on pin 11.  This may be an artifact of the homemade cable   used
>> for this experiment.  The HP cable clearly has an  overall  shield
>> (visible through the cable sheath) and may have  internal coax  or
>> twisted pair for these PPS signals.
>> When pin 5 and pin 11 are  observed together, the usual GPS  sawtooth
>> pattern is  evident.
>> Someone discovered  earlier that the both units will blink  their green
>> ON lights if  the front-panel switch on either unit is set to 23  dBm
>> vice the  normal 17.  Obviously each unit can communicate its  switch
>> status to the other unit.  They use pins 6 and 10 to do  that.   Pin 10
>> (on the Ref-1 unit) is high (~5V)  if the switch on   the Ref-1 unit is
>> in the 17 dBm position, and low in the 23 dBm  position.  Pin 6 (on the
>> Ref-1 unit) gives the same indications  for the switch on the  Ref-0
>> unit.
>> The serial  data on pin 1 is transmitted at 9600 baud,  with a burst of
>> data  every second.  The signal idles at logic low  (near 0V) and  rises
>> to logic high (near 5V) during the burst.  This  may  be the standard
>> for TTL (not RS-232) transmission of serial data, or  it  may be
>> inverted.  The first few characters of one burst  were  hand-decoded
>> from a scope trace as 0x40, 0x40, 0x45, 0x61,  0x0B, or ASCII  "@@Ea".
>> This appears to be the Motorola Oncore  binary data format,  although
>> "Ea" does not appear to be a valid  Motorola command or  response.
>> Perhaps the hand-decoding was in  error.
>> One can use  SatStat, talking to the Ref-0  (non-GPS) box, to issue
>> queries and commands  to the GPS  receiver.  The results are
>> inconsistent, but it seems that   at least some of the queries get
>> through and trigger responses.   If  the Ref-0 box is actually talking
>> to the GPS receiver, it  must be doing so  through the interconnect
>> cable.  The  specific wire in the cable used  for this (if any) has not
>> yet  been identified.
>> An earlier post  speculated that the  computer in each unit only had two
>> UARTs.  This  does not  seem possible.  Clearly each unit uses one UART
>> to   communicate with the J8 diagnostic port.  The Ref-1 unit needs
>> another  UART to communicate with the GPS receiver. And both units  need
>> to be able  to transmit the legacy Lucent timecode message  out the J6
>> (RS422/1PPS)  port.  Perhaps there is a  transmit-only UART coded into
>> the FPGA, or  perhaps one of the  UARTs is timeshared with the Lucent
>> message, or perhaps  there is  another UART chip hidden somewhere on the
>> board.
>> It  seems  unlikely that the two units are sending serial data to  each
>> other.   (No such data was observed on the  interconnect.)  Instead,
>> they appear  to communicate their  state to each other by means of logic
>> levels on  various pins of  the cable.  The logic functions of pins 6
>> and 10 have   already been identified.  Further research is  needed.
>> Cheers!
>> --Stu
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