Hi Ok so the correct pairs should be:
A 1 15 B 2 14 C 3 13 D 4 12 E 5 11 F 6 10 G 7 11 ground 8 8 Bob > On Nov 4, 2014, at 4:38 AM, Stewart Cobb <[email protected]> wrote: > > 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 > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
