Biomedical Engineering Reference
In-Depth Information
Figure 6.27
An external “brick”
15-V dc power supply is used to power the cardiac simulator.
5 V dc is generated onboard for the
digital portions of the circuit.
Firmware for the Cardiac Simulator
Figure 6.28 shows the state machine for the main loop. The main routine performs the
following tasks:
• Reads the LVS_Delay (left-ventricular sense time delay) hex switch setting and stores
the value.
• Checks to see if the LV_P_IN signal was found outside the 180-ms window.
• Checks for an atrial capture event (A_CAP_EVENT
fl
flag set to 1). If the atrial capture
event is true and the atrial capture action
flag is enabled, the DO_A_CAP subroutine
is run and the user returns to the main loop. The atrial capture action
fl
flag is used to
disable atrial events in the main loop. If an atrial capture event is detected but the
action
fl
flag is cleared.
• Checks for a ventricular capture event (V_CAP_EVENT
fl
flag is not set to 1 (enabled), the event
fl
fl
flag set to 1). If the ventricular
capture event is true and the ventricular capture action
fl
flag is enabled, the DO_V_CAP
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