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The Design of an Electronic Bicycle Monitor (EBM)

The Design of an Electronic Bicycle Monitor (EBM). Team P118: Gary Berglund Andrew Gardner Emrys Maier Ammar Mohammad. Background. Electric Bicycle Components Bicycle Battery Controller Motor. Relevance. Current interface Battery Speed Available systems Commercial ‘off the shelf’

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The Design of an Electronic Bicycle Monitor (EBM)

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  1. The Design of an Electronic Bicycle Monitor (EBM) Team P118: Gary Berglund Andrew Gardner Emrys Maier Ammar Mohammad

  2. Background Electric Bicycle Components Bicycle Battery Controller Motor

  3. Relevance Current interface Battery Speed Available systems Commercial ‘off the shelf’ Phone apps Electric Bicycle Monitor (EBM) Integration Weight Power efficient Used to track trips and monitor bicycle electronic systems

  4. Requirements

  5. System Block Diagram Caption for visual aid(s)

  6. Requirements from top level: • Display bicycle status • Requirements from other subsystems: • None User Display

  7. Solution being implemented: Graphics LCD • Needs from other subsystems: • Power supply • 3.3V @ 25mA (82.5mW) main logic • 27.9V @ 22mA (613.8mW) back light • Total max power: 696.3mW • MCU • Integrated graphics driver • Four wire connection for touch sensing User Display (Hardware)

  8. Solution being implemented: Graphics LCD • Software status: • Need software flow chart for GUI User Display (Software)

  9. Requirements from top level: • Logged Lat/Long for post processing • Using Google Maps or similar program to view route • Requirements from other subsystems: • None Removable Memory

  10. Solution being implemented: Secure Digital • Needs from other subsystems: • MCU • SPI bus • Power supply • 3.3V @ 200µA (660µW) Standby • 3.3V @ 100mA (330mW) Active Removable Memory

  11. Solution being implemented: Secure Digital • Software status: • Need software flow chart for SD functions Removable Memory

  12. Requirements from top level: • Handlebar mounted • Water resistant • Requirements from other subsystems: • None Case

  13. Solution being implemented: Garmin Nuvi • Needs from other subsystems: • All subsystems • Physical constraint • PCB Mounting hole coordinates match case • Power supply • Power button & USB connector coordinates match case Case (Hardware)

  14. Solution being implemented: Garmin Nuvi • Software status: • N/A Case (Software)

  15. Solution being implemented: Offset Differential Amplifier • Requirements from top level: • Range of 35 to 41V • Requirements from other subsystems: • MCU • Output 0 to 3.3V • Linear relationship to battery voltage • Needs from other subsystems: • PSU • 3.3V, Ground • MCU • ADC input Battery Voltage Sensor

  16. Battery Voltage Sensor

  17. Solution being implemented: Housekeeping • Software status: • A 10-bit ADC will be read every 1 ms and saved into a variable for the display to use Battery Voltage Sensor

  18. Solution being implemented: Hall Effect Sensor • Needs from other subsystems: • PSU • 3.3V, Ground • MCU • ADC input • Requirements from top level: • Range of 0A to 30A • Requirements from other subsystems: • MCU • Output 0V to 3.3V to ADC • Linear relationship to measured current Battery Current Sensor

  19. Battery Current Sensor

  20. Solution being implemented: Housekeeping • Software status: • A 10-bit ADC will be read every 1 ms and saved into a variable for the display to use Battery Current Sensor

  21. Solution being implemented: Hall Effect Sensor • Needs from other subsystems: • PSU • 3.3V, Ground • MCU • Interrupt capable input • Requirements from top level: • Range of 0 to 30 mph • Requirements from other subsystems: • MCU • Output pulse when magnet passes the sensor Wheel Speed Sensor

  22. Wheel Speed Sensor

  23. Solution being implemented: Interrupt • Software status: • When a pulse is received, the wheel speed timer value is recorded and the timer is reset. • The recorded timer value is used to calculate the current velocity of the bike. Wheel Speed Sensor

  24. Software Milestone: 0 Hardware Milestone: 0 • Requirements: • Interface with the existing bicycle battery voltage (35-40V typical) • Provide stable, well-regulated power to each EBM subsystem • Automatic shutdown at low voltage level (35V) • Additional Aspirations: • Avoid wasting battery power with high efficiency design • Minimize complexity • Objectives: • Identify all voltage/current needs from subsystems • Identify subsystem I/O software requirements • Develop “Power Budget” and battery charge life • Research specific solutions and identify component candidates • Design and model hardware schematic • Alpha test under laboratory conditions • Integrate into EBM subsystems and measure performance Power Management System

  25. Software Milestone: 0 Hardware Milestone: 0 Power Management System • Specific power supply parts have not yet been selected pending other subsystem part selection

  26. Software Milestone: 0 Hardware Milestone: 0 Solution being implemented: A mix of DC-DC Buck Converters and LDO Linear Regulators • Requirements from top level: • Step down 35-40V main battery voltage to first subsystem voltage level • Needs from other subsystems: • MCU: Low voltage shutdown command • Subsystem power budget numbers Power Management System Requirements from other subsystems, “Power Budget”:

  27. GPS

  28. Solution being implemented: • Getting position and time information GPS • Needs from other subsystems: • Power System: • 5 V @ 34 mA (170 mW) • MCU: • I2C bus to send the data every one second • External memory: • Place to save the data • Requirements from top level: • Record latitude, longitude, and time • Save them to the SD card through the MCU • Use the saved data to show the path of the trip • Requirements from other subsystems: • None

  29. Microcontroller

  30. Solution being implemented: Microcontroller • Needs from other subsystems: • Power System: • 3.3V @ 800µA (2.6mW) running mode • 3.3V @ 22µA (72µW) Idle or sleep mode • Requirements from top level: • Analog to digital Converter (2 channel) • SPI bus for SD card • EPMP bus for Graphical LCD • Pulse counter for speed • Requirements from other subsystems: • Current sensor: • Analog reading of battery current • Voltage sensor: • Analog reading of battery voltage • GPS: • Position and time information • LCD screen: • X and Y axis of the touched place Microcontroller

  31. Will be divided into three aspects: • Power system, voltage and current sensor: • Power supply along with multimeter will be used • Measuring the voltage and current to check requirement and accuracy • Wheels speed sensor: • Regular bike will be used • Checking number of pulses per revolution • GPS, LCD, and MCU: • No external component needed • Checking the results using software application • GPS using google map • LCD and MCU using the programming software (MPLAB X?) • Heartbeat LED testing will be used after adding any component to the design Testing

  32. Meeting: • Bi-weekly with Dr. Gibbs • Weekly with group members • Documentation • Shared folder to organized documents • Documents naming convention for convenient access • Tasks: • Divided into multiply subsystem • Each subsystem include: choosing components, designing circuit schematics, PCB, and programming • Overlapping responsibility to ensure general knowledge about other subsystem Project Management

  33. “Wrap Up” Plan (very early) Project Timeline (Preliminary)

  34. Powerpoint Slide Assignments Weekly Goals

  35. Budget Currently unknown, but relevant at every step in the design process Safely assumed at less than $1000 in components No upper limit specified by sponsor Will factor into component selection

  36. Conclusion/Questions

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