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From: guilford@csv.rpi.edu (Jim Guilford)
Newsgroups: comp.sys.amiga
Subject: Problem with JTIME
Message-ID: <30@rpicsb8>
Date: Mon, 31-Aug-87 21:20:55 EDT
Article-I.D.: rpicsb8.30
Posted: Mon Aug 31 21:20:55 1987
Date-Received: Sat, 5-Sep-87 02:23:10 EDT
Sender: nobody@rpicsb8
Reply-To: guilford@csv.rpi.edu (Jim Guilford)
Distribution: na
Organization: RPI CS Dept, Troy, New York
Lines: 47
Keywords: JTIME, clock/calendars, hardware
Summary: My clock chip won't clock

[]

I recently built "JTIME: a Real-Time Clock for the Amiga" by Micharl Keryan.
It is a clock/calendar that plugs into the second joystick port. The plans
and description came on an amiga disk (I forget where I got the original
from. It might have been a fish disk or a BBS, but I can't recall). It is
based around the RTC58321 clock/calendar chip by SaRonix. I ordered the chip
from Jameco, who give the part number as MSM58321RS.

After wiring up a small circuit board, I inspected it and tested it. It
didn't work. I pulled the chips, did some more testing, and found a short
between two wires, I fixed that, repopulated the board, and plugged it in. I
found that I could read and write the date/time with no problem, but that
the time was not advancing. It seemed to be doing a good job of emulating a
battery backed up slice of ram!

I am looking for help and/or suggestions on what may be wrong. Here are my
observations. I don't think I trashed any of the chips as I can successfully
read and write to the clock/calandar. My schematics give the 58321 five
unconnected pins: 10, 11, 12, 14, and 15. My voltmeter gives one of the pins
(I can't recall which, but I think it was 14) either an intermediate level
voltage, or a time varying voltage, I can't tell which. I am wondering if
some caps or resistors are missing, or whether I'm supposed to feed back a
clock signal back into the chip someplace. Unfortunately, I haven't been
able to come up with a spec sheet for the chip.

I thought that maybe the MSM58321RS might not be a RTC58321, but it seems to
work quite well other than counting. This is quite a coincidence unless it
is design to clone the RTC, but with some extra features or bugs.

The RTC is supposed to have an internal trimed and sealed quartz crystal,
and the schematics show no external analog components (e.g. resistors or
caps).

Does anyone out there in Netland have any clue as to what is going on? The
chip is semi-expensive (and Jameco's minimum order is $20), so I don't want
to order a new chip and find out that nothing changed. I decided to rough it
out and build it myself to save some money.

To avoid cluttering the net, I would appreciate it if you would email any
replies to me.  Of course, if there is enough interest, I will summarize the
results to the net.

Thanks in advance for any help you can offer me. I am . . .

Jim Guilford
guilford@csv.rpi.edu              or          ...seismo!rpics!guilford