Wheelchair Navigation Aid

Technical Content ReviewBy Rob Riel

OverviewPlanned Workflow

Top Level System Design

Hardware Design

Software Design

Mechanical Design

Planned WorkflowDesign hardware devboard, use for testing, work

out any gremlins

Re-spin devboard once for connectors for final product

Develop Software after dev board obtained

Hardware Design

Software Design

Debug Hardware

Top Level System DesignSystem processes data from range finding

sensors

User is alerted visually and via sound of object encroachment.

Product contains LCD screen which displays useful information

Product also lights path of wheelchair with high power LED lighting

Top Level Design cont.

Hardware Design• Hardware incorporates proven design practices

such as:– UART-> FTDI -> USB

• Total board breakout connectors for access to all pins. (great for debugging and development)

• Stable 8Mhz operation

• Over engineered power traces to prevent burnouts

• Onboard Temp monitoring

Hardware Design cont.

Hardware Layout

Rendered Product Electronics

Software DesignSoftware incorporates maximum efficiency by

using:ISRs whenever possibleLightweight LCD drivers designed in houseDSP instructions which take 1 clk vs normal 4 clks.

Because drivers are designed in house complete control is maintained over data flow, decreasing time to market due to debugging

Overall Code Diagram

Run TimeRoutines

andData

Processing

SystemAnd

PeripheralSetup

VariableAnd

StructureDefinition

s

Variable and Structures

Define Loop Vars

Define Constants

Define MacrosFor Screen

Define Sensor Struct

Define ScreenStruct

Define UARTStruct

System and Peripheral Setup

Setup Oscillator

Setup Watchdog

Setup Pin State(TRIS)

Set InitialPin Output

Setup ADC Regs

Setup Interrupts

Setup UART Init Regs

Initialize Screen

Run Time Routines & Data Processing

Fetch & Store Sensor Data

Compare Sensor Data to

Thresholds

Update Screen

ISR For Change Mode

ISR For SendingData Via UART

Update State Machine, Store

to Screen Structure

Calculate Bat Remaining

Mechanical Design Control Box

Mech Design LCD Box

Schedule