Specifications

Theory of Operation 3
• Smaller footprint: 3.3" x 2.1".
• Maximum baud rate is 19.2K.
• Lower power requirements: 55ma @ +5Vdc ±10% standby, 160ma average
when touched, 240ma peak.
• Lower cost.
E271-2201 PC-Bus Controller
• Half-slot PC-Bus controller (for ISA and EISA systems).
• Host communication can be polled or interrupt-driven.
• I/O address and interrupt (IRQ) selectable through software or jumpers.
• AccuTouch E271-141 and DuraTouch E271-142 controller emulation.
E271-2202 Micro Channel Controller
• Half-slot controller for PS/2 computers with Micro Channel architecture.
• Host communication can be polled or interrupt-driven.
• I/O address and interrupt (IRQ) set via the "automatic configuration"
procedure on the IBM Reference Disk.
THEORY OF OPERATION
Each SmartSet controller has the circuitry needed to interface an Elo resistive
touchscreen to a host computer. Functionally, the circuitry may be divided into the
following categories:
• Drive circuitry which applies electrical signals to the touchscreen.
• A measurement subsystem which detects and digitizes signals returned from
the touchscreen.
• Interface circuitry (serial, PC-Bus, or Micro Channel).
• A microprocessor which directs the operation of the various controller
subsystems.
The following section describes how each of these component subsystems operate
to measure coordinates from an Elo touchscreen.