Philips PageWriter TC70 - System Overview and Architecture

Theory of Operation Overview
8-2 PageWriter TC 70 Cardiograph Service Manual
Overview
At a system level, the PageWriter TC70 cardiograph performs acquisition, analysis, printing,
storage, and transfer of ECG waveforms and other patient clinical data.
The PageWriter TC70 cardiograph consists of three major subsystems:
 Main board
A main control board built around a powerful embedded processor (Marvell PXA270)
with extensive I/O facilities, running Windows CE 5.0. The PageWriter TC70 application
software runs on the main board, which supports the display and user-input subsystems.
 Print controller
A FPGA-based (Altera Cyclone-II) control circuit, embedded in the main board that
provides all the real-time management of the printer.
 Patient Interface Module (PIM)
An embedded processor (Marvell PXA270) running Windows CE 5.0, coupled with a
signal acquisition board employing Philips proprietary mixed-signal ASIC technology for
ECG acquisition. The PIM communicates with the main board through USB.
Hardware Logical View
Control of the PageWriter TC70 cardiograph is provided by application software running on
the main board, interacting with numerous hardware and software subsystems. The following
are high-level descriptions of these various subsystems.
Main Board
The main board contains loader software and the Windows CE kernel image in its internal
flash memory 64 MB.
At system boot, a basic interface configuration is performed by the loader and then the
Windows CE kernel loads. When Win CE loads, the application launcher runs, verifying
system and executable images before loading the main application. All interaction with the
user is through the
Athena_APP application. This application software is stored in internal Flash
memory.
Figure 8-1 illustrates the devices and interfaces provided by the main control board.