From pfimdt93@hvdc.hv.se Wed Apr 20 10:28:30 1994 Received: from eken.hv.se by char.vnet.net with SMTP id AA01299 (5.65c/IDA-1.4.4 for ); Wed, 20 Apr 1994 10:27:33 -0400 Received: from pcpost.hv.se by eken.hv.se with SMTP id AA21710 (5.65c/IDA-1.4.4 for ); Wed, 20 Apr 1994 14:37:27 +0200 Date: Wed, 20 Apr 94 14:38:13 +0100 From: PER FINANDER Subject: Link-interface To: bed@char.vnet.net Message-Id: <940420143813.3f5-2.2b8-pfimdt93@hvdc.hv.se> Status: RO Hello, Here is the schematics in windows metafile format. You build this interface on your OWN risk because I can't promise that this circuit works to 100 percent. I disclaim all responsibilities. Some hints of you decide build one: * Use a shielded cable between interface <=> TI85 and connect the shield to the ground. * The LM3302 can be replaced by a LM339N (the LM339 is used in the real link85-interface) I've included a small program "TESTLINK" to test the interface. To use it write : "TESTLINK 1" if the interface is connected to com1. Do not connect the TI85 to the interface when running this program, otherwise the TI85 thinks it's a transmission and tries to respond. You'll get 4 numbers: Numbers Possible errors: 3,1,2,0 <= Correct, the interface works 0,0,0,0 <= Wrong Com-port or no powersupply to the LM3302/LM339 3,2,1,0 <= RTS/DTR or CTS/DSR connections have been exchanged If you write "TESTLINK 1 X" you must press a key between every number, but this makes it possible to measure the voltage on the TI85 connection. IO1 GND | | <=|=|=|||||| | IO2 Number IO1-GND IO2-GND 1 (3) > 4 V > 4 V 2 (1) > 4 V < 0,5 V | If the voltage on these two lines are reversed 3 (2) < 0,5 V > 4 V | exchange IO1- and IO2-connections on the plug 4 (0) < 0,5 V < 0,5 V I think this will help you.