Provided by: linuxcnc-uspace_2.9.0~pre0+git20220402.2500863908-4build1_amd64 
NAME
lcd - Stream HAL data to an LCD screen
SYNOPSIS
loadrt lcd fmt_strings=""Plain Text %4.4f\nAnd So on|Second Page, Next Inst""
FUNCTIONS
lcd (requires a floating-point thread). All LCD instances are updated by the
same function.
PINS
lcd.NN.out (u32) out
The output byte stream is sent via this pin. One character is sent every thread
invocation. There in no handshaking provided.
lcd.NN.page.PP.arg.NN (float/s32/u32/bit) in
The input pins have types matched to the format string specifiers.
lcd.NN.page_num (u32) in
Selects the page number. Multiple layouts may be defined, and this pin switches
between them.
lcd.NN.contrast (float) in
Attempts to set the contrast of the LCD screen using the byte sequence ESC C and
then a value from 0x20 to 0xBF. (matching the Mesa 7i73). The value should be
between 0 and 1.
PARAMETERS
lcd.NN.decimal-separator (u32) rw
Sets the decimal separator used for floating point numbers. The default value is 46
(0x2E) which corresponds to ".". If a comma is required then set this parameter to
44 (0x2C).
DESCRIPTION
lcd takes format strings much like those used in C and many other languages in the printf
and scanf functions and their variants.
The component was written specifically to support the Mesa 7i73 pendant controller,
however it may be of use streaming data to other character devices and, as the output
format mimics the ADM3 terminal format, it could be used to stream data to a serial
device. Perhaps even a genuine ADM3. The strings contain a mixture of text values (which
are displayed directly), "escaped" formatting codes and numerical format descriptors. For
a detailed description of formatting codes see: http://en.wikipedia.org/wiki/Printf
The component can be configured to display an unlimited number of differently-formatted
pages, which may be selected with a HAL pin.
Escaped codes
\n Inserts a clear-to-end, carriage return and line feed character. This will
still linefeed and clear even if an automatic wrap has occurred (lcd has no
knowledge of the width of the lcd display.) To print in the rightmost column it is
necessary to allow the format to wrap and omit the \n code.
\t Inserts a tab (actually 4 spaces in the current version rather than a true
tab.)
\NN inserts the character defined by the hexadecimal code NN.
As the ',' character is used in the format string to separate LCD instances
it must be represented by \2C in the format string. (the decimal
separator is handled differently)
\\ Inserts a literal \.
Numerical formats
lcd differs slightly from the standard printf conventions. One significant
difference is that width limits are strictly enforced to prevent the LCD display
wrapping and spoiling the layout. The field width includes the sign character so
that negative numbers will often have a smaller valid range than positive. Numbers
that do not fit in the specified width are displayed as a line of asterisks
(********).
Each format begins with a "%" symbol. (For a literal % use "%%"). Immediately
after the % the following modifiers may be used:
" " (space) Pad the number to the specified width with spaces. This is the default
and is not strictly necessary.
"0" Pad the number to the specified width with the numeral 0.
"+" Force display of a + symbol before positive numbers. This (like the - sign)
will appear immediately to the left of the digits for a space-padded number and in
the extreme left position for a 0-padded number.
"1234567890" A numerical entry (other than the leading 0 above) defines the total
number of characters to display including the decimal separator and the sign.
Whilst this number can be as many digits as required the maximum field width is 20
characters. The inherent precision of the "double" data type means that more than
14 digits will tend to show errors in the least significant digits. The integer
data types will never fill more than 10 decimal digits.
Following the width specifier should be the decimal specifier. This can only be a
full-stop character (.) as the comma (,) is used as the instance separator.
Currently lcd does not access the locale information to determine the correct
separator but the decimal-separator HAL parameter can be used to choose any desired
separator.
Following the decimal separator should be a number that determines how many places
of decimals to display. This entry is ignored in the case of integer formats.
All the above modifiers are optional, but to specify a decimal precision the
decimal point must precede the precision. For example %.3f.
The default decimal precision is 4.
The numerical formats supported are:
%f %F (for example, %+09.3f) These create a floating-point type HAL pin. The
example would be displayed in a 9-character field, with 3 places of decimals, . as
a decimal separator, padded to the left with 0s and with a sign displayed for both
positive and negative. Conversely a plain %f would be 6 digits of decimal, variable
format width, with a sign only shown for negative numbers. both %f and %F create
exactly the same format.
%i %d (For example %+ 4d) Creates a signed (s32) HAL pin. The example would display
the value at a fixed 4 characters, space padded, width including the + giving a
range of +999 to -999. %i and %d create identical output.
%u (for example %08u) Creates an unsigned (u32) HAL pin. The example would be a
fixed 8 characters wide, padded with zeros.
%x, %X Creates an unsigned (u32) HAL pin and displays the value in Hexadecimal.
Both %x and %X display capital letters for digits ABCDEF. A width may be specified,
though the u32 HAL type is only 8 hex digits wide.
%o Creates an unsigned (u32) pin and displays the value in Octal.
%c Creates a u32 HAL pin and displays the character corresponding to the value of
the pin. Values less than 32 (space) are suppressed. A width specifier may be used,
for example %20c might be used to create a complete line of one character.
%b This specifier has no equivalent in printf. It creates a bit (boolean) type HAL
pin. The b should be followed by two characters and the display will show the first
of these when the pin is true, and the second when false. Note that the characters
follow, not precede the "b", unlike the case with other formats. The characters
may be "escaped" Hex values. For example "%b\FF " will display a solid black block
if true, and a space if false and "%b\7F\7E" would display right-arrow for false
and left-arrow for true. An unexpected value of 'E' indicates a formatting error.
Pages The page separator is the "|" (pipe) character. (if the actual character is
needed then \7C may be used). A "Page" in this context refers to a separate format
which may be displayed on the same display.
Instances The instance separator is the comma. This creates a completely separate
lcd instance, for example to drive a second lcd display on the second 7i73. The
use of comma to separate instances is built in to the modparam reading code so not
even escaped commas "\," can be used. A comma may be displayed by using the \2C
sequence.
AUTHOR
Andy Pugh
LICENSE
GPL