Panasonic VP-0187A
==================
2017/08/06

It is unknown keyboard from Panasonic with Hirose Cherry M8 and 6P6C connector.

Pictures:
http://imgur.com/a/GAZE7

Hirose Cheery M8 switches:
https://deskthority.net/wiki/Cherry_M8



Scan
----
The keyboard is comprised of some of 4000 series IC without microcontroller.


    RST>-----------+---------------+
                   |               |
            TC4520 |        TC4520 |
            --------- carry ---------
    CLK>--->|row    |------>|col    |
            |counter|Q3     |counter|
            ---------       ---------
             Q012            Q012
              |||             |||
              |||             ABC   TC4028
              |||           ---------
              |||           |decoder|
              |||           ---------
              |||            |||||| col[0..7]
              ABC TC4512     vvvvvvv   pull down
            ---------- <----|+++++++|--100K--+
            |data    | <----|+++++++|--100K--+
    STATE<--|selector| <----|+++++++|--100K--+
            | 7 to 1 | <----|+++++++|--100K--+
            ---------- <----|+++++++|--100K--+
                row[0..7]   | 8x8 matrix     |
                            |                -
              TC4078        |               GND
              ------        |
    SENSE<----| OR |========+ OR'd row[0..7]
              ------

- TC4520BP - Dual Binary Up Counter 
- TC4028B  - BCD-to-Decimal Decoder
- TC4512BP - 8-Channel Data Selector
- TC4081BP - Quad 2-Input AND Gate
- TC4071BP - Quad 2-Input OR Gate
- TC4078BP - 8-Input NOR/OR Gate


Matrix
------
        0       1       2       3       4       5       6       7
    --------------------------------------------------------------------
    0   ESC     1       2       3       4       5       6       7
    1   8       9       0       -       ^       BS      INS     DEL
    2   TAB     Q       W       E       R       T       Y       U
    3   I       O       P       @       [       ]       F2      F1
    4   CTRL    A       S       D       F       G       H       J
    5   K       L       ;       :       RETURN  UP      F3      F4
    6   SHIFT   Z       X       C       V       B       N       M
    7   SPACE   ,       .       /       LEFT    RIGHT   DOWN    HOME



6P6C connector pinout
---------------------
1. VCC
2. Clock     - sends clock to binary counter TC4520
3. Key State - indicates hi if key selected by counter is active
4. Sense     - indicates lo if any key is active while Reset is hi.
5. Reset     - resets counter and drives all column
6. GND

      123456
    ,--------.
    | |||||| |
    |        |
    `--____--'
       plug


Ping configuration
------------------
AVR ATmega32u4 is used as protocol converter.

    PD0: Clock. Counter couts up at falling edge.
    PD1: Key State. Hi if selected key is activated.
    PD2: Sense. Lo if any key is activated while Reset is Hi.
    PD3: Reset. Resets counters at riging edge.
