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Blood Pressure Monitor Design Reference Manual, Rev. 0

Freescale Semiconductor

4-1

Chapter 4

Embedded Software Description

Here is a description of all the software modules in the blood pressure monitor demo.

4.1

Introduction

The purpose of the blood pressure monitor is to indicate the pulse pressure (the systolic pressure minus the

diastolic pressure) of a patient. This is implemented through the use of a cuff wrapped around the patient’s

arm, and measuring the pressure and pressure differential of that cuff while air is put into or out of the

system. Moreover, the blood pressure monitor must be able to perform many other functions, such as:

•

Display information

•

Provide audio feedback

•

Keep statistical records

•

Using USB or ZigBee communications, send statistical feedback to a PC for further analysis

4.2

Software Design Goals

The software design pursues these goals:

•

Modularity — The software must be completely modular and with as little cohesion as possible.

This modularity should be reflected in ease if making changes, if adding new functionalities and

modules, or if modifying existing ones.

•

Interoperability — Modules must not have any blocking functions. This makes it possible to allow

other modules to be kept up-to-date.

4.3

Software Architecture

The software architecture on the blood pressure monitor was designed in this way: application software

can be found on the main.c file; from here, the main() routine can call different services and hardware

features. Services will have direct contact with hardware on the MCU. The hardware has a hardware

abstraction layer that eases migration to another MCU. The real time clock (RTC) can be seen as a complex

driver which can service other functions, and is used as the system clock. All modules that depend on

time-triggered functions take their time base from the RTC.

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