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the question for power concerns the circuit was simplified as much as possible. The FSM was

simplified to 3 states named "Disarmed" (or 0), "Armed" (or 1), and "Active" (or 2) to describe

their functionality. A state diagram can be found in figure C-1 in appendix C. "One-Hot"

encoding was used allowing each state to have its own flip-flop in the FSM. This allowed the

system to catch a glitch and handle it much easier than classical encoding. A clock frequency had

to be selected for the counter and flip-flops. The clock could not be too fast because that would

require a very large counter to keep time but also could not be too slow so that inputs were

properly handled. This balance was reached with a clock frequency of 1kHz. This clock was

implemented using a 555 chip. Then the amount of time for the alarm to sound was selected to

be in the 30 second range due to power concerns. With the clock frequency and the time range

needed a 16 bit counter was selected. The last bit of the counter was the output bit to tell the

FSM it was time to change states. In order to save space and power it was decided that a PROM

would be used for all the combinational logic between the states of the FSM. Four, four bit

counters were used in the construction of the prototype as well as two dual D flip-flops. In the

final design it is suggested that one quad D flip-flop is used as well as one 16 bit counter to

simply construction as well as save space and power draw of the circuit. A simplified truth table

programmed into the PROM can be found in table C-1 in Appendix C. A complete circuit

diagram can be found in figure C-2 in Appendix C.

C-2 Explanation of Engineering Drawings and Data

The state diagram of the finite state machine shows the progression through each state. If

the FSM would go to multiple states, then Disarm takes preference, then Arm. Looking at the

schematic diagram, the 3 FD chips are the D Flip-Flops that make up the FSM. The PROM is

programmed with all the combinational logic for the system. The CB16CE is our 16 bit counter

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 85 86

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Zoombak A-GPS Universal Locator Guía de usuario Pagina 21