TS-3200 User’s Manual
Technologic Systems
05/21/2009
12
EN is an active high signal, raised whenever the LCD addresses are being read or written.
D0 – D7 are bi-directional, buffered copies of the data bus and carry all data and commands to the
LCD.
Figure 5 is not the standard pin-outs given for LCD displays. But this pin-out allows a standard ribbon
cable to be used when the ribbon cable is attached to the backside of the LCD. Example code for the
LCD display is on the utility diskette for the TS-3200.
8 Matrix Keypad Support
The DIO2 port, signals DIO2_0 through DIO2_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 #. 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. Please see the sample code
included on the utility disk for further information on the translation table.
Matrix keypad support is enabled or disabled using
INT15h, Function B040h
(see Appendix D ). 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 the utility diskette for example code.
When enabled, the DIO2 signals DIO2_0 through DIO2_7 are not available as general I/O.
9 Real Time Clock
The Dallas Semiconductor DS12887 is used for the PC compatible battery-backed real-time clock. It is
a completely self-contained module that includes a Motorola 146818 compatible clock chip, the 32.768
kHz crystal, the lithium battery, and 114 bytes of battery-backed CMOS RAM. It is guaranteed to
maintain clock operation for a minimum of 10 years in the absence of power. It is located at the
standard PC I/O addresses of Hex 070 and 071. The top 32 bytes of battery-backed RAM (index 60h
through 7Fh) are not used by the BIOS and are available for user applications.
10 Watchdog Timer and Software Reset
The Intel 386EX contains a 32-bit watchdog timer (WDT) unit that can be used as a watchdog timer or
as a software reset function. A system reset is asserted when the WDT times out preventing a system
“hanging” due to a software bug. To prevent a WDT timeout, the application must periodically “feed”
the WDT by writing to a specific I/O location (WDTCLR). The value loaded into the 32-bit down-counter
(WDTRLDH and WDTRLDL) allows timeout values as high as 170 seconds. This value will be referred
to as the “Reload Constant”.
The 32-bit “Reload Constant” determines the maximum time allowed between each Watch Dog Feed.
After the WDT has been started, it cannot be turned off and the “Reload Constant “ cannot be
changed. This makes it impossible for a crashed program to cause a system to “hang”.
The following steps outline how to start the Watch Dog Timer:
Summary of Contents for TS-3200
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