Motorola MC75 connector pinout

This picture represents Motorola/Symbol MC75 bottom view, keyboard/screen down. I placed pin numbers right to left because if you look to male connector on cradle - numbers will be left to right. If my numbering is nit correct it should not be a problem to change to correct numbering.

I have a single slot cradle for MC75 and RS-232 cable (25-102776-02R). So I took a multimeter and checked connections between RS-232 DB9 and MC75 connector in cable and mini USB and MC75 connector in cradle. The table following summarizes what I found out.

Motorola/Symbol MC75 connector pinout

Pin #	Interface	Goes to	Description/ Wire color
1	Charge	?	Charge +5.4V at least 1.4 A
2	?	?	?
3	RS-232	DB9:4 pin#14	DSR ?Wakeup
4	RS-232	DB9:1 DB9:6	CD DTR
5	RS-232	DB9:7	CTS
6	RS-232	DB9:8	RTS
7	RS-232	DB9:3	Rx
8	RS-232	DB9:2	Tx
9	?	?	?
10	USB	USB:1	+5 V
11	RS-232 USB	DB9:5 USB:4	GND
12	USB	USB:3	D+
13	USB	USB:2	D-
14	?	DB9:4 pin#3	DSR ?Wakeup
15	Charge	Charge:GND DB9:5 USB:4	GND
16	Charge	Charge:GND DB9:5 USB:4	GND

Note for pin #1: There is no direct contact between pin #1 and positive connector of Charge input. I suppose there are some protective circuits both in cradle and charging cable. In cradle there should be a circuit which lows voltage from +12V to charging +5V. If +5.4V applied to positive (central) pin of charging cable there is +5.4V at pin #1.
Note for pin #10: This +5V voltage is generated by MC75 itself and intended to power USB device. I tried it with 8Gb flash and portable keyboard - it worked. Of course you should keep in mind that any USB devise will drain power from MC75's battery, so do not overload it.
Note for pins #3 & #14: There is a short circuit between these pins in RS-232 cable. Apparently one pin is used to generate DSR for RS-232 communication. My guess - it is pin #3. Pin #14 is making MC75 wake up when RS-232 cable is connected and prevents MC75 from powering down by time-out.

I hope this information will be useful to MC75 users! At least you can charge from any +5V source (cell phone charger, etc.)! Just place your MC75 face down to table, bottom towards you and connect +5V to most right pin and GND to most left. Easy to remember - +5V = Red = R = Right! :)