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Humble Hubble

Humble Hubble. Team 18 Tim Brown. Abstract. The proposed project is a self-aiming telescope. This telescope will obtain its global position and the local time via GPS. It will then automatically orient itself to point at a user selected target (star) using a variety of onboard sensors.

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Humble Hubble

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  1. Humble Hubble Team 18 Tim Brown

  2. Abstract The proposed project is a self-aiming telescope. This telescope will obtain its global position and the local time via GPS. It will then automatically orient itself to point at a user selected target (star) using a variety of onboard sensors. Background: http://www.nasa.gov/images/content/708180main_hubble_lose_spiral_full_full.jpg

  3. PSSCs An ability to establish a coordinate system based on the telescope's absolute global position via a GPS chipset, and relative orientation based on an accelerometer and electronic compass. An ability to compensate for combined variations in the Earth's gravitational and magnetic field, and variations in telescope geometry and mounting configurations via electronic user calibration.

  4. PSSCs An ability to retrieve celestial coordinates and targets via Bluetooth from an external host. An ability to automatically move and point the telescope at the designated target using feedback loops from integrated motor encoders. An ability to allow the user to manually override the telescope's target coordinate using an onboard electronic control interface, and to display information regarding headings on an onboard LCD.

  5. Software Design Considerations • Flexibility in workload • Ability to manage multiple communications protocols simultaneously • Maintain as much user functionality as possible while waiting for sensor data • Capable of trig functions (or simulation) for stellar target calculations

  6. Software Design Decisions • Completely Interrupt-driven code • Enables each communications interface to demand attention when it needs it • Allows sensor initialization to take place “in the background” • Allows the processor to pass into a low-power “idle” state while not busy • Use look-up tables for trig calclulations

  7. Memory Map • Executable code • Sine lookup tables • LCD character lookup table • Bluetooth message lookup table • Current position, Current Target, Automatic Target, Manual Target • Button/encoder states. • Message Buffers for each communication protocol

  8. Peripherals Used • I2C x2 – Sensor Breakout, Motor Encoders • UART x2 – Bluetooth, debugging serial port • SPI – GPS chip • PWM x2 – 2 motors • Timers x2 – Timed interrupts

  9. Vss (Ground) Vdd (3.3V regulated) Vcc (5.0V regulated) Hold Power On On/Off Interrupt V+ (7.2V Unregulated) Motor 1 – Brake Motor 1 – PWM Motor Enable Motor 2 – Brake Motor 2 – PWM SDA SCL Vdd(3.3V regulated) Vss(Ground) Header 1 11 wires Breakout Board Gyro, Compass, Accelerometer I2C Port 34 wires Main Board Auxiliary Board GPS RX GPS TX GPS ON / OFF Bluetooth RESET Bluetooth CTSBluetooth RTS Bluetooth RXD Bluetooth TXD Header 2 8 wires Motor 1 Leads Motor 2 Leads Integrated Encoder Module VEX 269 Motor Integrated Encoder Module VEX 269 Motor I2C Port 24 wires Pan Assembly Tilt Assembly SDA SCL Vcc(5V regulated) Vss(Ground) V+ (7.2V Unregulated) Vss(Ground) 7.2V NiMH Battery

  10. Header 1 11 wires Main Board Rotary Encoder 1 Rotary Encoder 2 Rotary Encoder 3 Vss (Ground) Vdd (3.3V regulated) Vcc (5.0V regulated) Hold Power On On/Off Interrupt V+ (7.2V Unregulated) Motor 1 – Brake Motor 1 – PWM Motor Enable Motor 2 – Brake Motor 2 – PWM / 6 IO pins I2C Port 3 SDA SCL PIC 24FJ64GB106μC SDA SCL Vdd(3.3V regulated) Vss(Ground) Hold Power On On/Off Interrupt Motor 1 – Brake Motor 1 – PWM Motor Enable Motor 2 – Brake Motor 2 – PWM PWM Port 1&2 Header 2 8 wires GPS RX GPS TX GPS ON / OFF Bluetooth RESET Bluetooth CTSBluetooth RTS Bluetooth RXD Bluetooth TXD UART 1&2 GPS RX GPS TX GPS ON / OFF Bluetooth RESET Bluetooth CTSBluetooth RTS Bluetooth RXD Bluetooth TXD ICSPHeader PGE1 /3 Pins V+ (7.2V Unregulated) Vss(Ground) I2C Port 2 I2C Port 2 SDA SCL SDA SCL Vcc(5V regulated) Vss(Ground) Reset Button Manual / Auto Button Shift Register LCD DataClockShift 8 pin parallel / 2 interrupts 4 Pin UART Voltage Translator Serial Port / 2 IO pins Menu Button 1 Menu Button 2

  11. Software Design (Main Loop) Stop Interrupt Start Shut Down Peripherals (GPS) Init Wait 1 Second Wait for Interrupts (Idle) Cut power to Voltage Converters End

  12. Initialization and Calibration Init Calibrate Interrupt Initialize Registers for Peripherals Load Polaris as Target for Calibration Start GPS chip Allow user to correct position via rotary encoders Initialize LCD Move to Polaris Init Bluetooth Store encoder offsets Initialize Sensors End Calibrate End Init

  13. Motors and UI UI Interrupt Motor Interrupt Check Button States Auto or Manual De-bounce Update Button Positions Get Target From Bluetooth Get Target From Manual Check Encoder States Update Motor speed + direction Update Encoder Positions End Motor End UI

  14. Communication Peripherals Data Event Interrupt Decode Message Type Process Data Invoke Appropriate Response End Data Event

  15. Questions?

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