For those who are interested:
the schematics of a Nokia DLR-3 cable

These pictures are not made by my own, I found them somewhere in the web, but the site I got them from seems to be discontinued, so I decided to make this available. If you know where they are from, or if there are any problems with this schematics, please let me know. You will notice that there is a mask-programmable PIC in the cable, so there is nearly no chance to make the cable by oneself. Connecting pin 3 to GND seems to switch 3V source on pin 4 on The phone sends MBUS frames from MBUS to XMIC with 9600,9O1 (1F:48:00:4E:00:02:01:02:xx:xx) XMIC needs to ACK these frames (1F:00:48:7F:xx:xx) During this, the phone accepts AT commands on FBUS with 19200,8N1 The 15k on XMIC switch the phone to data mode. If you change this to 1k5, the phone will recognize a headset

© by N. Hüttisch (nobbi@nobbi.com)