Final Presentation P14452 Overview MSDI Review MSDII Customer - - PowerPoint PPT Presentation

Final Presentation

P14452

• MSDI Review

○ Customer Needs ○ Requirements ○ Functional

Decomposition

○ Concept Selection ○ Detailed Design

Overview

• MSDII

○ Detailed Design

Revisited

○ Build ○ Test

• Reflect

○ What Remains ○ Lessons Learned

MSDI Review

Customer Needs

Requirements

Functional Decomposition

Concept Selection

Benchmarking

Device Our DAQ MSR145 MSR160 Slice Micro Total Cost ~$80 $1018 $1417 ~$7000 Number of Sensors 2 1 1 3 Max Sample Rate 20,000 Hz 50 Hz 1,000 Hz 120,000 Hz Capture Duration 4M Samples (8GB SD) 2M Samples 2M Samples 4M Samples (8GB SD) Input Voltage 0-2.5V 0-10V 0-10V 0.5-23.5V Bit Width 16 Bit 12 Bit 12 Bit 16 Bit

• Thermal Analysis
• Vibration Analysis
• Analog Signal Processing
• Digital Control

Detailed Design Overview

Thermal Analysis

• Resonant frequency of

compressor found to be 6 Hz in X and Z, and 12 Hz in Y

• Theoretical resonant

frequency of PCB calculated to be 8450 Hz

Vibration Analysis

• 2.5mm Jack
• MAX7403 Filter

○ 8th order Low-pass filter

○

Adjustable cutoff frequency

• MAX9939 PGA

○ Adjustable gain factor ■ 0.2 - 157 V/V

Analog Signal Path

• Freescale KL25Z

○ 48 MHz ○ 32-bit ○ SAR ADC

■

16-bits

■

1 MSPS

○ SPI ○ USB

Digital Control

MSDII

• Enclosure Selection
• Printed Circuit Board Design
• Microcontroller Roulette
• Bill of Materials

Detailed Design Revisited

Enclosure Selection

• BEX Series 1

○ Aluminum ○ Gaskets and Endcaps ○ Flange Mounts ○ Perfect size for PCB

• Needs Adapter Plate

PCB Design (Revision 1)

• Single Board

○ Small Footprint ○ Low Profile

• Freescale KL05Z
• Problems

○ Missing Protection Diodes ○ USB Backwards ○ No Battery Connector ○ Signal Connector Pads Incorrect ○ Wrong SD Pads

• Daughter Board

○ Signal Conditioning ○ Power ○ microSD

• Problems

○ Battery Connector ○ Diodes Backward ○ Power Switch ○ Buck-Boost Enable ○ SD Pad inverted ○ Header Spacing

PCB Design (Revision 2)

Microcontroller Roulette

• STMicro STM32F373

○ 3 Sigma-delta ADC ○ SD Interface ○ $250 Dev Board

• TI MSP430

○ SAR ADC ○ <8 MHz Clock ○ < $5 Dev Board

• Cypress PSOC

○ Analog Front-end ○ Configurable Logic ○ Small Input Range

• Freescale KL05z

○ 48 MHz ○ 4 KB RAM ○ No USB ○ $13 Dev Board ○ MBED

• WINNER: Freescale KL25z

○ 48 MHz ○ 16 KB RAM ○ USB ○ $13 Dev Board ○ MBED

Bill of Materials

Item Quantity Cost FRDM-KL05Z 1 $12.95 BOX Exclosure 1 $10.93 PCB 1 $33 MAX7403 (LPF) 2 $3.76 ea. MAX9939 (PGA) 2 $1.68 ea. LiPo Battery 1 $1.20 Sensor Ports 2 $0.50 ea MISC ~$10 Total Cost: ~$80

• Enclosure Vibration Testing
• PCB Testing

○ Power Conditioning ○ Analog Signal Path

• Software Testing

○ Microcontroller Firmware ○ DAQ Configurator

Testing Overview

• B & K shaker table
• SigLab software
• Accelerometer on shaker

table and top of enclosure

Enclosure Vibration Testing

Enclosure Vibration Testing

Chirp - w/o Rubber Endcaps Chirp - w/ Rubber Endcaps Random - w/o Rubber Endcaps Random - w/ Rubber Endcaps

• The output of the boost converter is dependent on the resistors R1

and R2

• The design had the resistors reversed but this was fixed

PCB Testing: Power

• The Li-po charging chip was

working

• This is proved by the status

pin being high when the battery is charging

• The status pin is connected

to an input on the microcontroller

PCB Testing: Power

PCB Testing: Analog Path

Sensor input from function generator 0-2 Vpp input @ 1kHz Output of PGA VOUTA = VCC/2 - Gain * (VINA+ - VINA-) + Gain * VOS VOS-INHERENT = (VOUTA - VCC/2)/Gain Output of Filter Vout range 0.25V - VDD VCOM= VDD/2 VOUT = (VIN - VCOM) + VOS

PCB Testing: Low-pass filter

Fc= 1MHz, Fout= 10Hz Fc= 1MHz, Fout= 100Hz Fc= 1MHz, Fout= 11kHz Fc= 900kHz, Fout= 10kHz fC = fCLK / 100

• Completed:

○ SD Card ■ Read ■ Write ○ PWM (LPF) ○ ADC ■ Internal Square Wave

• In Progress:

○ ADC External Signals ○ PGA ○ On-board 3-axis Accelerometer

SW Testing: Firmware

• Completed:

○ File Manipulation ■ New ■ Save ■ Open ○ Exit ○ Load / Store Settings

• In Progress:

○ Generation of Standalone Executable

SW Testing: Configuration

• Mechanical

○ Seal Enclosure ○ Install Power Switch

• Analog

○ Update PCB Design to Fix Problems Found in Testing ○ Find replacement for PGA (Wide Input)

Reflect: What Remains?

• Digital

○ Complete Firmware Testing ○ USB Mass Storage

• Documentation

○ User Manual ○ Developer Manual

Reflect: Lessons Learned

• Mechanical

○ Existing enclosures are abundant ○ Cross-Discipline knowledge is important ○ Use intuition to validate simulation results

• Electrical

○ READ Datasheets ○ Consult Experts ○ Design Twice, Build Once ○ Simulate Early, Simulate Often ○ Triple check designs before

• rdering

Reflect: Lessons Learned

• Computer

○ Best Processor != Best Solution ■ Dev Board vs. Full Custom ■ ADC Roulette ■ PSOC Trap ○ SD Cards - Not That Easy

• Overall

○ Communication with Customer ■ Frequency ■ Expectations ■ Get it in Writing ○ Testing in MSDI ■ Importance of a Prototype

Questions?