Malfunctioning of that leads to arythmic heart beating. Design a pacemaker (pulse generator) which generates electrical pulses to trigger heart, if it senses irregular (or low) heart rate. This pacemaker is typically inplanted inside body near chest. Assume appropriate design challenge and design an embedded system which can sense and trigger (if required) heart to bring heart back to normal rythmic beating. For this design develop

(a) Functional model/ FSM which describes functioning of system.

(b) Hardware block diagram which describes typical hardware building blocks.

(c) Software architecture which describe typical functions/drivers/tasks required in program.

(d) Discuss special design challenges for this design and suggest solutions/approach.

(e) Suggest list of components with justification.

Mumbai University > Electronics Engineering > Sem 6 > Embedded System and RTOS

Embedded system has a very wide application in medical monitoring systems. Many parameters of human body are monitored electronically to keep an eye of the human body for easy indication for the doctors. There are various embedded systems in medical industry, right from small digital thermometer to high end equipments like EEG, ECG etc. Let us consider a simple device like heart rate monitor.

Requirement analysis

To implement the heart rate monitor, we need some sensors that will be mounted on the human body. The signals are to be processed and accordingly the heart rate is to be indicated on a display connected to the system. There may be buzzers to indicate the high value and low value of the heart rate i.e, if the heart rate falls below a particular value, it will beep and similarly if the heart rate crosses a particular value, the Buzzer will beep.

Hardware block diagram

The sensor is used to sense the pulses from the heart. These pulses have a lot of noise and are of very low amplitude. Hence this signals need processing. The signal processing block performs this processing and ADC converts it to the required format for the microcontroller. The microcontroller then compares the actual heart rate with the upper and lower limits and accordingly switches on the buzzer if required. The actual value of the heart rate calculated by the microcontroller is also displayed on the display.

System model

As shown in the figure the left arrow indicates the beginning of the flow of the system. The left block has a sensor Input and processing of the signal. The Digital Signal is given to the microcontroller, which in turn controls the buzzer according to the read value and also displays the value of the display device.

Software Architecture (modules, drivers)

The various software models required for the heart rate monitor can be listed as follows:

Timer module: The timer module will keep a track of the time from which the pulses count is measured. The time maybe one minute and the number of pulses measured in this one minute are to be counted by the counter module.

Counter module: As the name says this module will count the number of pulses sensed by the sensor in the time period control by the timer module. Based on this count, the buzzer module decides whether the buzzer needs to be on or not.Also the output of this module works as an input to the display module to display the heart rate.

Buzzer module: the Buzzer module will compare the actual readings of the heart rate and the set values. If there is a discrepancy, i.e, more than upper limit or less than lower limit the buzzer will be turned on.

Display module : This module will simply read the value given by the counter module and display the same on the specified display.

Hardware selection

The sensors required in this case will be judge the ECG sensors to measure the pulses. There will be an amplifier required to amplify the power signal given by the sensor. The signal will have to be processed and then given to the microcontroller. Finally we need to decide upon the microcontroller for the application. For the microcontroller selection we need to check the number of inputs and output ports required. We need to also find the speed of operation for meeting the deadlines of the system. The arm processor or any small size processor will be suitable for this application.