Modular Swimming Pace Aid ECE 445 Group Members: Igor Fedorov, Ryan Cook, Michael Chan Professor Carney (TA Ryan May)

Introduction Pacing is an imperative part of swimming at any level Our project provides a visual queue for swimmers to swim at a certain pace

Objectives Timing Modularity Convenience Real-time updating

System Overview

Display Module Overview

Display Module PCB Microcontroller Communication Amplifier Power supply

Power Supply Energy Source: 3 C batteries in series –4.5 V, kJ MOSFET reverse polarity protection circuit –Allows current to flow freely in positive direction, negative current limited to MOSFET reverse leakage current LDO used to supply 3V logic rail

Power Supply Test Results TestDisplay ModuleController Module Efficiency (%) V rail voltage (V) V rail voltage (V)33 Reverse leakage current (uA)** 0.07 Battery lifetime* (years) *Battery lifetime calculated assuming device is used 10 hours/week for 52 weeks **Reverse leakage current of MOSFET used falls outside the dynamic range of testing equipment

LED Driver Decoder translates 4 bit address from microcontroller to drive one pair of LED’s Signal from decoder gets amplified by BJT amplifier circuit Amplifier circuit has minimal losses and current biases LED’s at optimal operating point (25 mA)

Controller Module Overview

Controller Module PCB Communications Power supply Touchpad LCD Microcontroller

Communications Overview START Intended Recipient ID Sender ID Operation Mode Operation Mode Dependent Byte 1 Operation Mode Dependent Byte 2 STOP 0xA5 (four times) 0x?? 0x5A Operation ModeByte to Transmit Timing Functionality Mode0x11 Test Synchronization Mode0x22 Add Panel to Modular Strong Mode0x33 Signal Transmit Success0x44 Update System Time0x55 Update Panel ID0x66 End Timing Mode0xFF

Communications Testing Top waveform is a byte transmitted from one msp430 through the linx modules. The bottom waveform is the output on the other end of the linx modules. The top waveform is 4 bytes of information transmitted from one msp430. The bottom waveform is the transmit line of another MSP430, where it echoes the received data. Data is transferred across linx modules.

Controller and Display Module Testing View Registers in Code Composer Studio to ensure –Proper data reception –Proper data storage LED indicators to show when certain functions were being executed Code Composer Studio Debugger

User Interface Overview Enable full control of system Simple control & navigation Real time updates

LCD & Touchpad Clear description of current state Simple way to navigate menus LED backlight control Set Swim Distance & Pace Directional controls Center button select

User Interface Testing Touchpad Use LEDs on touchpad to determine direction pushed Transmit UART code using touchpad Check for received UART code on other MSP430 – Use TX/RX pins – Use CCS to examine registers LCD Set up initialization code Send single characters to LCD after initialize Place single characters at arbitrary locations on screen Write strings to screen Invert bits for a string to show highlighted text

Full System Testing Requirements 1. Modular Design 2. Timing tests 3. Real time update 4. Low power usage Testing 1. Ran system with between 1-3 panels 2. Timed laps with different distances and paces. 3. Submit update to system, measure laps 4. Measure power draw during each phase: wait, receive, and light up

Timing & Update Results Set Time & Distance 20 seconds – 10 meters – 20 meters – 30 meters 30 seconds – 10 meters – 20 meters – 30 meters Measure Time Average 20.2 seconds – 19.9 seconds – 20.3 seconds – 20.4 seconds Average 30.1 seconds – 29.7 seconds – 30.2 seconds – 30.4 seconds

Successes Hardware 4 completely functional PCB’s Low power design Battery powered Software Pace time is within half a second of desired pace Each panel generates a unique ID Transmit/Receive data at 9600 baud rate

Difficulties Hardware Complying with Electronics Shop’s PCB requirements System wiring Design changes Debouncer circuit Power supply efficiency Lack of test points Software Transmit/Receive at 9600 baud rate consistently transmit/receive Touchpad sensitivity

Recommendations Hardware Design PCB’s such that all connections are on bottom layer Finalize design before submitting PCB request If board size/capacitive/inductive effects are not issues, avoid surface mount parts Add an msp430 to the communications module Software Unique system Identification Manipulation of individual panels – Allow non-uniform distances between panels – Set for speed variance at different locations Set pace by speed Use gesture controls on touchpad for different input modes