NAME

       matrix_kb  -  Convert integers to HAL pins. Optionally scan a matrix of IO ports to create
       those integers.

SYNOPSIS

       loadrt matrix_kb config=RxCs,RxCs... names=name1,name2...

       Creates a component configured for R rows and N columns of matrix keyboard.

       If the s option is specified then a set of output rows will be cyclically toggled,  and  a
       set of input columns will be scanned.

       The  names parameter is optional, but if used then the HAL pins and functions will use the
       specified names rather than the default ones. This can be useful for readbility and 2-pass
       HAL parsing.

       There must be no spaces in the parameter lists.

DESCRIPTION

       This  component  was written to convert matrix keyboard scancodes into HAL pins.  However,
       it might also find uses in converting integers from 0 to N into N HAL pins.

       The component can work in two ways, and the HAL pins created vary according to mode.

       In the default mode the component expects to be given a scan code from a  separate  driver
       but  could be any integer from any source. Most typically this will be the keypad scancode
       from a Mesa 7i73. The default codes for keyup and keydown  are  based  on  the  Mesa  7i73
       specification with 0x40 indicating a keydown and 0x80 a keyup event.
        If  using  the  7i73  it  is  important  to  match  the  keypad size jumpers with the HAL
       component. Valid configs for the 7i73 are 4x8 and 8x8.  Note that the component will  only
       work  properly with the version 12 (0xC) 7i73 firmware. The firmware version is visible on
       the component parameters in HAL.

       In the optional scan-generation mode the matrix_kb.N.keycode pin changes to an output  pin
       and  a  set  of  output  row  pins  and  input  column pins are created.  These need to be
       connected to physical inputs and outputs to scan the matrix and return values to HAL. Note
       the  negative-logic parameter described below, this will need to be set on the most common
       forms of inputs which float high when unconnected.

       In both modes a set of HAL output pins are created  corresponding  to  each  node  of  the
       matrix.

FUNCTIONS

       matrix_kb.N
              Perform  all  requested  functions.  Should  be  run in a slow thread for effective
              debouncing.

PINS

       matrix_kb.N.col-CC-in bit in
              The input pin corresponding to column C.

       matrix_kb.N.key.rRcC bit out
              The pin corresponding to the key at row R column C of the matrix.

       matrix_kb.N.keycode unsigned in or out depending on mode.
              This pin should be connected to the scancode generator if hardware such as  a  7i73
              is  being  used.  In  this  mode  it  is  an input pin. In the internally-generated
              scanning mode this pin is an output, but will not normally be connected.

       matrix_kb.N.row-RR-out bit out
              The row scan drive pins.Should be connected to external hardware pins connected  to
              the keypad.

PARAMETERS

       matrix_kb.N.key_rollover unsigned r/w (default 2)
              With  most  matrix  keyboards  the  scancodes are only unambiguous with 1 or 2 keys
              pressed. With more keys pressed phantom keystrokes can appear. Some  keyboards  are
              optimised  to reduce this problem, and some have internal diodes so that any number
              of keys may be pressed simultaneously. Increase the value of this parameter if such
              a keyboard is connected, or if phantom keystrokes are more acceptable than only two
              keys being active at one time.

       matrix_kb.N.negative-logic bit r/w (default 1) only in scan mode
              When no keys are pressed a typical digital input will float high.  The  input  will
              then be pulled low by the keypad when the corresponding poll line is low.  Set this
              parameter to 0 if the IO in use requires one row at a time to be high, and  a  high
              input corresponds to a button press.