Explain the design of a Pacemaker (Pulse generator) which generates electrical pulses to trigger the heart if it senses

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Explain the design of a Pacemaker (Pulse generator) which
generates electrical pulses to trigger the heart if it senses an
irregular heart-beat. This pacemaker is typically implanted in the
body near the chest. The designed system must sense and trigger the
heart and bring it back to its rhythmic beat.
a) Draw a FSM for the system
b) Hardware block diagram and suggest the hardware
components
c) Software architecture which describes the various
tasks/Functions/Drivers in the code
d) Discuss the various design challenges and suggest
solutions.