[time-nuts] FE5680A

Sam Reaves sam.reaves at gmail.com
Tue Mar 6 03:18:58 UTC 2012


Hello Group,

I just bought four of the FE5680A's that have the standard configuration
Pin 1+15, Pin 2 Gnd, Pin 3 Lock, Pin 4 +5V Pin 5 Gnd, Pin 6 1pps?, Pin 7
10MHz, Pin 8 TX, Pin 9 RX.

I have a LED with a 330 ohm current limiting resistor on pin 3 (the
74ACT240 can sink up to 24mA and I am well below that) for the lock
indicator. All of my units lock and produce 10MHz although the 1pps never
switches.

I can not get any of the units to communicate using the DB-9 connections. I
scoped the receive data into the unit all the way to the microcontroller.
The RS232 and TTL levels for the data look perfect as well as the timing
for 9600-N-8-1. However the unit never transmits any data.I scoped this all
the way to the micro as well. Not a pulse spike or anything.

Has anyone determined what the second serial interface is for? It seems to
me that it would not make any sense for FE to install the RS232 port if it
could not be used.

Any hints?

Thanks
Sam
W3OHM



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