Coinvox 22

Project: Coinvox 22
Featured:
State	Active
Members	xopr
GitHub	No GitHub project defined. Add your project here.
Description	Get an old payphone to work again
Picture
No project picture! Fill in form Picture or Upload a jpeg here

synopsis

I got myself a Coinvox 22, reasonably cheap. The downside is: the inner workings have been stripped out, so it's just a metal box with keypad and display, a handset with hookswitch and a smalltransformer.

No coin mech, no ringer, no phone.

inside

handset / hookswitch

• 2 differend reed switches
• 4 coils
• 2 3-pin SOT 23 (smd) diodes(?) (D1, D2: A7 P 45)

J1

|o  spk
|o| mic -
|o| mic +
|o  spk

J2

mic+ 2 |oo| 1 spk
 spk 4 |oo| 3 mic-
 NC1 6 |oo |5 n/c
 NO1 8 |oo| 7 P1
  P2 10|oo| 9 NO2

Note: SW1 switches first (about 2mm) when hanging up

keypad / display

• IC2: PCF8576T (Universal LCD driver for low multiplex rates, I²C address 38h)
• IC3: PCF8574T (Remote 8-bit I/O expander for I²C-bus with interrupt)

  Addresses tied to ground; address 20h.

J

SCL 2 |oo| 1 SDA
    4 |oo| 3 
GND 6 |oo |5 VCC
    8 |oo| 7 
Int 10|oo| 9 

Display

• 8 × 14 segment display, charachters are filles from the right
• 52 pins with the only the outer 9 connected (36)
• uses 4 backplane mode (all corners)

Segment layout

       15
   _________ 
 
  | \11 |   / |
 2|  \  |7 /6 |14
  |   \ | /   |
 10----  -----5
  |   / | \   |
 1|  /  |  \4 |13
  | /9  |8  \ |
   __________
        0       o12
 pin 3:N/C

Keypad

	col1 (P7)	col2 (P4)	col3 (P5)	col4 (P6)
row1 (P1)	n/c	1	2	3
row2 (P1)	n/c	4	5	6
row3 (P2)	N	7	8	9
row4 (P3)	Vol	*	0	#

To read out the keypad (on interrupt pullup), set one row low and read the column nibble. Repeat for each row. Low bit means key pressed.

LGCO-CH BTC15 DESKII

4 431 4223 0 22

Sticker

Landis & GYR

412197580 A

Version.mec: A

Date fab : 02/95

plans

• upload reference material of the Coinvox phones (hacktic, 't klaphek, telephone museums ([1][2][3][4][5][6][7])
• experiment with my (front fed) coin mech (or look for a top fed mech that fits)
• experiment with a cisco phone (see if I can use the softkeys and the AUX port to read quarters or just Euro coins
• connect an ATA to an old phone

todo

• identify ICs, obtain datasheet, determine pinouts