360 10. SYSTEM LEVEL DESIGN
10.8 CHAPTER PROBLEMS
1. For the SeaPerch ROV provide adjustable speed control for each motor. This advanced feature
requires several modiﬁcations including a proportional joystick and pulse width modulation
signals to the motor. The joystick currently in use provides a simple on and off signal. A
proportional joystick provides an X and Y output DC signal proportional to the joystick
deﬂection on each axis. These signals may be fed to the analog-to-digital converter aboard
the MSP430. The X and Y signals captured from the joystick may be used to provide a pulse
width modulated signal with a duty cycle proportional to deﬂection.
2. For the SeaPerch ROV provide a powered dive and surface thruster.The current control system
provides a powered drive capability with the vertical thruster. The ROV returns to the surface
using its slightly positive buoyancy. To provide for a powered dive and surface capability, the
vertical thruster must be equipped with an H-bridge to allow for motor forward and reversal.
3. For the SeaPerch ROV provide left and right thruster reverse. Currently, the left and right
thrusters may only be powered in one direction.To provide additional maneuverability, the left
and right thrusters could be equipped with an H-bridge to allow bi-directional motor control.
4. For the SeaPerch ROV provide proportional speed control with bi-directional motor control.
Both of these advanced features may be provided by driving the H-bridge circuit with PWM
5. Construct the UML activity diagrams for all functions related to the weather station.
6. It is desired to updated weather parameters every 15 minutes. Write a function to provide a
15 minute delay.
7. Add one of the following sensors to the weather station:
• rain gauge
You will need to investigate background information on the selected sensor,develop an interface
circuit for the sensor, and modify the weather station code.
8. Modify the weather station software to also employ the 138 x 110 LCD. Display pertinent
weather data on the display.