purdue airbus
DESCRIPTION
Purdue Airbus. Software Design. Jigar Gandhi - John-Taylor Smith - Chandler Wall - Eric Zarowny. PWM – written and tested* UART – written but not tested Camera – outlined in pseudo code SD Card – written but not tested Battery Management – outlined in pseudo code - PowerPoint PPT PresentationTRANSCRIPT
Purdue AirbusSoftware Design
Jigar Gandhi - John-Taylor Smith - Chandler Wall - Eric Zarowny
Software Development Status
• PWM – written and tested*• UART – written but not tested• Camera – outlined in pseudo code• SD Card – written but not tested• Battery Management – outlined in pseudo code• Ground Station – outlined in pseudo code
Software Design Considerations
• We need to spend as little time as possible in interrupts because we have so many.
• We need as much of SRAM as possible for image buffering.
• We need the transfer speed to the SD card to be as high as possible so we will not be using SPI.
• We need a compression ratio that strikes a balance between image quality, time spent compressing and image size.
Arrangement
PWM
• Interrupt Based• Our transmitter only has the four channels necessary for
manual flight control.• The Autopilot board requires a fifth channel to control
what flight mode is currently activated.• The PWM output of our microcontroller will emulate a
RC transmitter and output specific pulse-widths.
PWM Program Flow Chart
UART
• Interrupt Based• Autopilot/Microcontroller UART• Receive telemetry data from the Autopilot.• Transmit new GPS coordinates to the Autopilot.
• Microcontroller/XBee UART• Receive a new flight mode from the ground station.• Receive new GPS coordinates from the ground station.• Transmit telemetry, battery, and image data to the ground
station.
UART Program Flow Chart
Camera
• VBLK indicates the period in which the camera will be outputting data
• HBLK indicates that the camera has data ready to be captured
SD Card
• Operates as a state machine.• After initialization, the card will enter an idle state.• When the image buffer on the microcontroller receives
data from the camera, a data ready signal will be sent to the card.
• The data will be sent to the card using 4-bit SD mode until the FIFO is empty, at which point the card will be sent a command telling it there is no more data.
• The card will then return to the idle state.
Battery Monitor
• Operates as a state machine.• To query the battery monitor from the idle state, a logic
high must be pulsed for a specified duration on the bus.• Once a second pulse is returned from the battery monitor,
a hexadecimal command can be sent to the monitor.• The command will execute, return the results asked for
and then return to the idle state.
Ground Station
• The Ground Station will be run on an Intel Atom board.• It will overlay the telemetry and battery data onto the
image data received from the microcontroller.