Example SWHW Model: System

1
Example SW/HW Model System
System description
Sensor Processing SW/HW
Sensor input

• UAH1 computer
• Software exists

Calibration Flag
Waits for input from sensor (sensor inputs
provided each 2ms). When input is available,
processes it (see SW description). Following
processing, checks state of Calibration Flag If
flag is set, conducts calibration processing.
(Calibration flag set each c ms where c is
distributed as N(50,100), cgt20). After
completion of sensor processing and calibration
(if performed), waits for next sensor input.
Purpose Determine mean processor utilization
and mean and max cycle time for 1,000 cycles.
2
Example SW/HW Model SW
Sensor input
Y
i1 to 10
Cal. Flag set
N
Process Sensor Data Part i
1000 FADD 2000 LD 2000 STO
Cal Processing
500 FADD 500 FMULT 1000 STO
Next i
3
Example SW/HW Model HW
UAH1 Computer performance LD 10 ns STO 12
ns FAAD 100 ns FMULT 300 ns
4
Example SW/HW Model Simplifying the model
Sensor input
Process Sensor data
10,000 FADD 20,000 LD 20,000 STO
Y
i1 to 10
Cal. Flag set
N
Process Sensor Data Part i
1000 FADD 2000 LD 2000 STO
Cal Processing
500 FADD 500 FMULT 1000 STO
Next i