Matrix Keypad Support - Technologic Systems TS-5700 User Manual

TS-5700 User's Manual Technologic Systems http://embeddedARM.com/

8 Matrix Keypad Support

The DIO2 port, signals DIO_0 through DIO_7, may be configured to support a 4 x 4 matrix keypad. When
enabled, BIOS firmware performs all the work, making the matrix keypad appear as a simple 16-key keyboard to
software. This allows the use of standard keyboard access routines. The default set of keys translated by the
BIOS consists of 0 – 9, A – D, *, and #. The # key is returned as an ASCII Carriage Return character (Hex 0D).
Because the user is writing the software, this set of keys is usually sufficient. However, a custom translation
table can be loaded, allowing the use of function keys, arrow keys, or any other key on the keyboard.
Matrix keypad support is enabled or disabled using INT15h, Function B040h (see Appendix E). Once enabled,
standard keyboard BIOS functions are enabled. Note that console redirection and the matrix keypad support are
mutually exclusive – console redirection must be disabled to use the keypad.
A matrix keypad can be used with console redirection only if the keypad is not used as stdin, but read from as a
hardware device. This is useful if one wishes to use console redirection or to use a keyboard as stdin. See
Section 18 for an explanation of console I/O and redirection. See the Technologic Systems download page for
example code.
ftp://ftp.embeddedarm.com/ts-x86-sbc/old-downloads/
When using a matrix keypad, the DIO signals DIO_0 through DIO_7 are not available as general I/O.
A Linux driver has been written for the Matrix Keypad, the Linux driver with full "C" source code can be found on
our website. Refer to the "Linux Developers Manual" on the Technologic Systems website.
14 5/2009