Circuit Schematics
TREAT
The TREAT is a PIC12F752 used to turn our lift fan on and off. It receives on and off commands from a Tiva on the DOG using software UART.
Lift Fan Driver
The lift fan driver circuit is a simple motor driver configured in low side drive. Because the lift fan only operates at one speed and one direction, the application did not warrant a full H-bridge driver. The diodes in series with the motor were provided by the SPDL and used for voltage regulation into the motor.
FARMER Main Power
The main power circuits are the lifeblood of our project. The Tiva on the FARMER operated with no protection board, so it was important to have a consistent, clean power source for it to run from. LED's were powered from the unregulated battery.
FARMER IMU
The IMU provided acceleration and gyroscopic data over an SPI interface. After running into problems with communication, we discovered that the drive capabilities on the MISO line of the IMU were very weak. Two inverting schmitt triggers maintained the correct polarity and cleaned up signal for consistent communications. For the FARMER the IMU was configured to impose a rising edge on INT1 when a step was detected. This edge was detected on the Tiva to see if the user was moving and corresponding to jumping would allow the hovercraft to move.
FARMER Bend Sensor
The bend sensor is a variable resistor that changes resistance when deformed. This circuit makes use of an op-amp to effectively convert the resistance of the sensor into a voltage. This voltage was then read by the Tiva on board ADC to determine when a user wanted to turn.
FARMER LED Driver
LED strips on the FARMER were used as visual queues to improve user understanding and experience. Our driver consisted of a buffer which ran three MOSFETs in a low-side drive configuration, giving us full control over each color individually. PWM was used to mix colors and change brightness.
FARMER Tiva Breakout
Breakout circuits provided convenient connections to all relevant Tiva pins using molex connectors.
DOG Main Power
The main power circuit for the DOG powered all of the circuits on the hovercraft except for the thrusters. Two batteries were used to obtain a 14.4V power rail which was used to power the lift fan and the LED's. Lower logic power rails provided clean operating power to all of our logic circuits.
DOG IMU
The IMU provided acceleration and gyroscopic data over an SPI interface. After running into problems with communication, we discovered that the drive capabilities on the MISO line of the IMU were very weak. Two inverting schmitt triggers maintained the correct polarity and cleaned up signal for consistent communications. For the DOG the raw IMU data was communicated back to the FARMER as prescribed by the class communications protocol.
DOG LED Driver
LED strips on the DOG were used as visual queues to improve user understanding and experience. Our driver consisted of a buffer which ran three MOSFETs in a low-side drive configuration, giving us full control over each color individually. PWM was used to mix colors and change brightness.
DOG Thruster Driver
The thrusters we selected were DC brushed motors mounted into ducted fan units. The motors drew a significant amount of current (measured at around 6.5A at normal operation), so the H-bridges readily available to us were not an option. Because ducted fans provide little thrust in reverse, we opted for a simple low-side drive configuration using a power MOSFET. This restricted us to unipolar motion in the motor, but it allowed much higher operating currents which we required. A large heatsink was used on the MOSFET to prevent overheating.
DOG Tiva Breakout
Breakout circuits provided convenient connections to all relevant Tiva pins using molex connectors.
