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

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

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.

Specifications General RequirementsSpecific RequirementsAcceptable Performance Read/Understand LEDs visible in any light Must see light Non-offensive to eyes Not blinding at night, visible during day Easy to read at a glance ± 3 mph Accuracy Smooth LightingCan’t see individual LEDs UseableEasy to install< 30 min Plug and playWorks out of the box *Ease of transferring trips*Push button to change for different trips DurabilityWeather proofWeather does not effect use of gauge functions Lifetime warrantyWork for the rest of customers life

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

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

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

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

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

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

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

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

Cascading Multiple TLC5940 chips

LED Controller Software Flowchart

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

Testing Results

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

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

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

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.

Testing

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.

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.

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

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.

Testing

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

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?

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

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

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