Specifications

CARROLL TOUCH Chapter 3 - General Programming Issues
Touch System Programmer’s Guide 3-9
HBC I/O Registers
Overview
The HBC communicates with the PC through the PC bus via three
consecutive I/O registers. The base address of these I/O registers is set
by the I/O address jumpers on the HBC board, and may be set in
increments of 16 to any I/O address between 200H and 3F0H inclusive.
The three I/O registers are defined in Table 3-1.
The touch controller may be used in polling mode or in interrupt mode.
In polling mode, the application software must check the Status
Register before sending or receiving data. In interrupt mode, the
application software must check the Status Register when sending data
to the touch controller, but may install an interrupt handler to receive
data from the touch controller. The interrupt number used is set by the
interrupt number jumpers on the HBC board, as described in the HBC
installation instructions. When using polling mode, set these jumpers to
none to prevent the HBC from generating any interrupts.
Sending a Touch Command to the HBC
The procedure used to send a touch command to the HBC is the same
for both interrupt mode and polling mode.
Before sending a command to the touch controller, you must first
perform an I/O read of the Status Register (Base Address + 1). Bit 0 of
the Status Register indicates whether the touch controller is ready to
Table 3-1. HBC I/O Registers
I/O Address Name
Read/
Write
Description
I/O Base
Address
Data Register R/W Used to send commands to
and receive reports from
the touch controller.
I/O Base
Address + 1
Status
Register
R Used to check the touch
controller communications
status (i.e. ready to receive
commands, reports
available).
I/O Base
Address +2
Hardware
Reset Register
W Used to reset the touch
controller.