Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!uiucdcs!uxc.cso.uiuc.edu!spica!hr
From: hr@spica.astro.uiuc.edu
Newsgroups: comp.sys.amiga
Subject: MIDI interface questions
Message-ID: <26800002@spica>
Date: 20 Apr 88 15:42:00 GMT
Lines: 27
Nf-ID: #N:spica:26800002:000:1233
Nf-From: spica.astro.uiuc.edu!hr    Apr 20 10:42:00 1988



I've got a question about connecting a MIDI interface to an Amiga.
When I tried to attach an ECE interface to my 1000, the system hung
after I told DMCS to activate the MIDI channel (serial port). As best
as I can figure out, when the serial port is active, the Amiga is sensitive
to voltages on pin 3 (receive). A constant 'high' voltage here will virtually
halt the machine. In this case high is 1.7V.

Any ideas as to what is the matter? Should the interface be sending a
negative voltage when it is not transmitting data? Shouldn't the Amiga be
able to ignore something like this? I'm guessing that the Amiga doesn't
have a real UART and that one of its chips, Paula if I read it right, is
trying to decode a character that isn't coming in. Another possibility
is that DMCS is trying to use some weird magic that is failing.

The serial port works when attached to either a modem or printer.

Unfortunately, I can't flatly accuse the ECE interface. My Amiga's
parallel port has been dead for awhile and since the 8250s are involved
in so much, it is possible that the problem is there. Has anyone had
experience with the ECE interface? Or is there a better one I should be
trying?

Thanks,
Harold Ravlin
hr@spica.astro.uicu.edu