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Design Review

Design Review. Analog Gauge w/ Digital Display. Team Digital Burnout Senior Design Fall 2011. Review Outline. Project Goal Specifications Hardware/Software Breakdown LED Control Display Design LCD Snapshot Goals Schedule Milestones. Project Goal.

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Design Review

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  1. Design Review Analog Gauge w/ Digital Display Team Digital Burnout Senior Design Fall 2011

  2. Review Outline • Project Goal • Specifications • Hardware/Software Breakdown • LED Control • Display Design • LCD • Snapshot Goals • Schedule Milestones

  3. Project Goal To provide an alternative to the standard analog speed gauge. This gauge will display information through lighting and will not require the use of a needle.

  4. Specifications

  5. Hardware Breakdown Bike/Bike Simulation Frequency Microcontroller Speed LED Controller LCD Display Control Bits LED’s

  6. Software Breakdown Input Signal Function to Calculate Odometer and Trip Values Function to Determine LED’s to light Function to Calculate Speed Function to Determine which LCD segments to activate Function to talk to LED Controller Function to Talk to LCD

  7. Receive bit from input pin Change of state? No Yes Read Timer Determine Period (current_time – prev_time) x 2 Determine Speed: (1/(T*25))*10

  8. Software for Odometer and Trip Calculations Yes Wait? No Yes Reset Trip? Odometer_Miles += Speed x Time No Trip_Miles = 0 Trip_Miles += Speed x Time

  9. Processors 2 vs 1 • Space • Resources (I/O, memory) • Multiple Tasks • Communication

  10. LED Controller Purpose: • Drive a large number of LEDs with a handful of processor pins Selected Part: • Manufacturer: Texas Instruments • Part number: TLC5940

  11. TLC5940 Selection Based on following characteristics: • High current drive capability of 120 mA • No external resistors required for each LED drive channel • Large number of channels (16) • Simple serial data input, can be implemented with bit-banging • Ability to control LED brightness with 64 steps from 0 mA to 120 mA

  12. TLC5940 Selection (cont) • Once latched, the TLC5940 will hold the drive channel settings until the chip is powered down • Ability to cascade multiple TLC5940 chips to drive more LEDs. No additional pins are required on the PIC

  13. Cascading Multiple TLC5940 chips

  14. LED Controller Software Flowchart

  15. LED Controller Hardware Schematic • Note: remaining PIC24H pin connects not shown

  16. Testing Results

  17. Testing Results

  18. Testing Results

  19. In Progress • BLANK pin enable not currently functioning • Additional research and trial/error required • Does dot correction mode produce sufficient ‘step/range’ of brightness control? • Look into grayscale mode • Make code more efficient, especially in area of the input data buffer that will be clocked into the TLC5940

  20. Previous Design Considerations Discrete LEDs • Pros • Usage of space (Small SMTs) • Quick visible representation of speed • Customizable

  21. Previous Design Considerations String LEDs • Pros • Customer is used to seeing a needle from an analog gauge • Ease of transition to buying a new product

  22. Prototype Display Design • Combine both the discrete LEDs and String LEDs • Achieve the best qualities of each, creating a display that is accurate, effective and attractive to the customer.

  23. Testing

  24. In Progress Manufacture a Top Piece • Use shielding to help focus individual light strands • Protect the internal components • The top piece should be easy to cut-out with the tools in the Biketronic’s Shop.

  25. LCD for the Odometer • Issues Considered for Selection • Size – use minimal space on the gauge face. • Number of digits – 7. • Programming Complexity. • Back light – visible in daylight.

  26. LCDs Considered • LCDs from Crystalfontz. • LCD from a custom bike gauge.

  27. Decisions Made • Decided against using the Crystalfontz LCDs • LCD too big for the size limitations. • Selected the custom LCD • Satisfies size requirement. • Product used previously on Harley speedometer gauge.

  28. Testing

  29. Design Flowchart & Block Diagram On the Sheet in front of you.

  30. Design Areas That Need Attention • Power Conditioning • Convert ~50v-60v from bike to a stable 3.6v • 3.6v should be sufficient for PIC24H and TLC5940 • Waiting on power requirement of LCD • Interfacing with the gauge chassis • PCB board design • Double sided? Multiple boards?

  31. Snapshot Goals • Face Design: • Complete first prototype • Input Detection and Speed Calculation using PIC24H • Full LCD functionality • Use LED controller to light face design prototype • Updated Website

  32. Schedule Milestones • October 11th • Snapshot goals • October 25th • Integrate all pieces (LCD, LED controller, etc.) into a single MCU • November 1st • Send off PCB design of entire gauge • November 8th • Final testing and complete integration

  33. ?

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