insn_config

rtlinux-3.2-pre3.tar.bz2 rtlinux3.2-pre3的源代码

INSN_CONFIG:

The first data element (data[0]) is an ID.

Generic return values:

  Bad ID: EINVAL  (should be EIO?)
  Length is wrong: EINVAL

  EAGAIN: changed arguments, retry (like command_test)


Notes:
  - Should we use the length as an ID? (no, cuz its dumb)
  - Should there be a generic flags parameter? (no)
  - Should trigger source configs return a token? (no)
  - Would it be better to have a special subdevice for trigger
    configuration? (no, because it goes against the "subdevices
    are independent" design.)
  - Should this configure generic triggers and return a token
    to be put into a command, or configure specific triggers
    that are tied to start_src, convert_src, etc.?


ID=INSN_CONFIG_BLOCK_SIZE: configure size of blocks to transfer during commands

	[0] - ID
	[1] - block size in bytes

	Writes back actual block size to [1].  Acts as query if block size is
	set to zero.

ID=xxx: counter configuration

  The subdevice has an accumulator which changes based on
  triggers.

  [0] - ID
  [ ] - flags
          generate command trigger when?
  [1] - mode
  [2] - source1_src
  [3] - source1_arg
  [4] - source2_src
  [5] - source2_arg
  [6] - gate_src
  [7] - gate_arg

  Modes:
    UP_COUNTER:
      acc++ on source1

    DOWN_COUNTER:
      acc-- on source1

    QUADRATURE:
      acc+=atan(source1,source2)

  Notes:
    - configuring pins vs. configuring triggers would make this
      easier


ID=xxx: counter configuration, up counter

  chanspec: used to determine particular counter channel

  [0] - ID
  [1] - flags
          up/down
  [2] - src (like command trigger)
  [3] - arg

  Notes:
    - too simple?  no gating

ID=xxx: counter configuration, up counter with gating
ID=xxx: counter configuration, quadrature


ID=xxx: set software gate
  [0] - ID
  [1] - set/clear gate




Applications:

 - Pulse counting:
   (STC: simple event counting)

    mode - up counter
    primary source - external line (+/-)

 - Pulse counting with gate:
   (STC: simple gated event counting)

    mode - up counter
    primary source - external line
    gate source - external line

 - Pulse length measurement:
    (STC: single pulse-width measurement)

    mode - up counter with gate
    primary source - timer
    gate source - external line (+/-)

    latch and reset on gate (-) transition

 - Timestamping
    (STC: buffered [non-]cumulative event counting,
          single period measurement)

    mode - up counter
    primary source - timer
    secondary source - external line

    latch on secondary source (+) transition

 - Up/Down counter:
    (STC: relative position sensing)

    mode - up/down counter
    primary source - external line
    secondary source - external line

    when(P)acc+=S?+1:-1

 - Quadrature counting:

    mode - quadrature
    primary source - external line 1
    secondary source - external line 2

 - Frequency generation:

    mode - up counter
    primary source - timer

    invert output on primary source trigger

 - Pulse generation

    (XXX needs work)
    mode - dual up counter
    primary source - timer
    secondary source - timer

    set output on primary source trigger
    clear output on secondary source trigger

  - Pulse Width Modulation

    same as above
    secondary source - timer (latch arg)

  - Frequency Shift Keying:

    mode - double up counter
    primary source - timer
    secondary source - timer
    gate - soft, or external line

    invert output on gate?primary:secondary source trigger

  -

ID=INSN_CONFIG_ALT_SOURCE: select alternate input source (internal calibration reference)

  [0] - ID
  [1] - source

ID=INSN_CONFIG_TIMER_1: Configure an external master clock and divisor
	to divide clock by.  Used with commands by setting scan_begin_src or
	convert_src set to TRIG_OTHER.

  [0] - ID
  [1] - trigger configuration (COMEDI_EV_SCAN_BEGIN, COMEDI_EV_CONVERT, etc.)
  [2] - primary input chanspec (also specifies polarity and edge/level )
  [3] - primary combining machine configuration (should always be 0x04)
  [4] - divisor