Ericsson Chatboard

Chatboard PS/2 hack

• can be "mounted" on your forearm for wearable/mobile operation

  

• since the original (microcontroler based) protocol is somewhat difficult to interface with (see below, serial communication, TTL levels, 9600 baud, 8N1, AT-style) i did a modification using the 7x7 keyboard matrix and the electronics taken from a normal PC keyboard
• attach it to your normal PS/2 keyboard port
• the keyboard generates key press / key release codes that can easily (when using Linux) be mapped to the according keys (e.g. via a loadable keymap)
• via a PS/2 to serial adapter it can also be connected to an Compaq iPAQ
• the PIC microcontroller for the PS/2 to serial interface can be switched to Twiddler 2 interface mode as well (i suggest using a Twiddler, the chatboard is mainly for ad hoc operation by people not used to it)

  

  

• PC keyboard electronics - all components can be (re-)mounted on the PCB side

  

• this is the PCB with all the SMD components removed

  

• rows and columns are wired (wiring / matrix diagram is below in this document)

  

• keyboard matrix connected to the electronics ripped from an arbitrary PC keyboard (fix components after each step with epoxyd glue)

• PC keyboard matrix hints (e.g. for the Cherry keyboard that i used here)

Tips

• should work with: T10s, T18s, A1018s, R250s Pro, GF788e, S868, SH888, I888 World
• FreeLock Project - adapter cable
• Ericsson RS-232 data cable pinout
• 7x7 keyboard based on PIC17C42
• 8x8 keyboard based on PIC17C42
• PIC16C63 datasheet
• Protocol:

  	9600 8N1 bi-directional serial communication
  	AT style
  
  	starts with (after phone is powered on)
  
  	phone => chatboard	chatboard => phone
  	1. AT
  				2.
  	3. OK
  	AT+CGMM
  	1100901
  	...
  

• Connector (Chatboard side)

  Connector (looking at the IC side)
  
          |    | | | | | | | | |     | |
  	1    2 3 4 5 6 7 8 9 10   11 12
                                             Philips
                                             CVS 5740
  1: + External power supply - from phone to chatboard
  2: RS232 input of the telephone (TTL) - chatboard output
  3: GND (digital)
  4: RS232 output of the telephone (TTL)Debug - messages appear here at 112KBaud when in debug mode - chatboard in
  5: +5V out
  6: Digital Input ? Test ? 
  7: Digital output ? Mute ?
  8: Enable external mike and speaker. Connect to GND to do so. 
  9: GND (Analogue)
  10: Unknown
  11: External microphone. 
  12: External speaker
  
  PC data cable
  1 - rt		- power supply (feeds TTL-RS232 converters?)
  2 - ws		- TTL-output (from computer RS-232 to phone)
  3 - sw		- GND
  4 - blau	- TTL-input (from phone to RS-232)
  5-6 connected
  
  cable to chatboard
  => uses pin 1-5
  
  h p e l         b y n
  
   1 2 3 4 5 6 7 8 9 0 <
  
    Q W E R T Z U I O P
  
     A S D F G H J K L
  
    ^ Y X C V B N M .
  
          _        < >    
  
  Keys:   49 = 7x7
  
  row 1: h p e l b y n
         | | | | | | |
  row 2: 1 2 3 4 5 6 7
         | | | | | | |
  row 3: Q W E R T Z U
         | | | | | | |
  row 4: A S D F G H J
         | | | | | | |
  row 5: ^ Y X C V B N
         | | | | | | |
  row 7: L K M . > < _
         | | | | | | |
  row 6: 8 9 0 < P O I
  
  ---
  columns
  1 - 7, U, ... column
  2 - 4, R, ... column
  3 - 2, W, ... column
  4 - 1, Q, ... column
  5 - 3, E, ... column
  6 - 6, Z, ... column
  7 - 5, T, ... column
  
  rows
  1 - h, p, ... row
  2 - 1, 2, ... row
  3 - Q, W, ... row
  4 - A, S, ... row
  5 - ^, Y, ... row
  6 - L, K, ... row
  7 - 8, 9, ... row
  
  

• Integrating PC keyboard electronics

  	Cable colors
  	1 - ws (bl/ws)
  	3 - sw (bl)
  	4 - gn (bn)
  	5 - gb (bn/ws)
  
  
  	looking at the tin layer side
  
  	|-
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  	|
  	|	3 5 4 1
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  	|	D D (2 x BC 547 - npn)
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