Final Presentation P14452 Overview MSDI Review MSDII Customer - PowerPoint PPT Presentation
Final Presentation P14452 Overview MSDI Review MSDII Customer Needs Detailed Design Revisited Requirements Build Functional Test Decomposition Reflect Concept Selection Detailed Design What Remains
Final Presentation P14452
Overview ● MSDI Review ● MSDII ○ Customer Needs ○ Detailed Design Revisited ○ Requirements ○ Build ○ Functional ○ Test Decomposition ● Reflect ○ Concept Selection ○ Detailed Design ○ 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 2 1 1 3 Sensors Max Sample 20,000 Hz 50 Hz 1,000 Hz 120,000 Hz Rate Capture 4M Samples 4M Samples 2M Samples 2M Samples Duration (8GB SD) (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
Detailed Design Overview ● Thermal Analysis ● Vibration Analysis ● Analog Signal Processing ● Digital Control
Thermal Analysis
Vibration 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
Analog Signal Path ● 2.5mm Jack ● MAX7403 Filter ○ 8th order Low-pass filter ○ Adjustable cutoff frequency ● MAX9939 PGA Adjustable gain factor ○ 0.2 - 157 V/V ■
Digital Control ● Freescale KL25Z ○ 48 MHz ○ 32-bit ○ SAR ADC ■ 16-bits ■ 1 MSPS ○ SPI ○ USB
MSDII
Detailed Design Revisited ● Enclosure Selection ● Printed Circuit Board Design ● Microcontroller Roulette ● Bill of Materials
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 ○
PCB Design (Revision 2) ● Daughter Board Signal Conditioning ○ Power ○ ○ microSD ● Problems Battery Connector ○ ○ Diodes Backward Power Switch ○ Buck-Boost Enable ○ SD Pad inverted ○ ○ Header Spacing
Microcontroller Roulette ● STMicro STM32F373 ● Freescale KL05z 3 Sigma-delta ADC 48 MHz ○ ○ SD Interface 4 KB RAM ○ ○ $250 Dev Board No USB ○ ○ ● TI MSP430 ○ $13 Dev Board SAR ADC MBED ○ ○ <8 MHz Clock ● WINNER: Freescale KL25z ○ < $5 Dev Board 48 MHz ○ ○ ● Cypress PSOC ○ 16 KB RAM Analog Front-end USB ○ ○ Configurable Logic $13 Dev Board ○ ○ Small Input Range 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
Testing Overview ● Enclosure Vibration Testing ● PCB Testing ○ Power Conditioning ○ Analog Signal Path ● Software Testing ○ Microcontroller Firmware ○ DAQ Configurator
Enclosure Vibration Testing ● B & K shaker table ● SigLab software ● Accelerometer on shaker table and top of enclosure
Enclosure Vibration Testing Random - Chirp - w/o Rubber w/o Rubber Endcaps Endcaps Chirp - Random - w/ Rubber w/ Rubber Endcaps Endcaps
PCB Testing: Power ● 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: Analog Path Output of Filter Output of PGA Sensor input from function Vout range 0.25V - VDD generator 0-2 Vpp input @ VCOM= VDD/2 VOUTA = VCC/2 - Gain * 1kHz VOUT = (VIN - VCOM) + VOS (VINA+ - VINA-) + Gain * VOS VOS-INHERENT = (VOUTA - VCC/2)/Gain
PCB Testing: Low-pass filter Fc= 1MHz, Fc= 1MHz, Fout= 10Hz Fout= 11kHz fC = fCLK / 100 Fc= 1MHz, Fc= 900kHz, Fout= 100Hz Fout= 10kHz
SW Testing: Firmware ● Completed: SD Card ○ Read ■ Write ■ ○ PWM (LPF) ADC ○ Internal Square ■ Wave ● In Progress: ADC External Signals ○ PGA ○ On-board 3-axis ○ Accelerometer
SW Testing: Configuration ● Completed: File Manipulation ○ New ■ Save ■ ■ Open Exit ○ Load / Store Settings ○ ● In Progress: ○ Generation of Standalone Executable
Reflect: What Remains? ● Mechanical ● Digital Seal Enclosure Complete Firmware Testing ○ ○ ○ Install Power Switch ○ USB Mass Storage ● Analog ● Documentation ○ Update PCB Design to ○ User Manual Fix Problems Found in Developer Manual ○ Testing Find replacement for ○ PGA (Wide Input)
Reflect: Lessons Learned ● Mechanical ● Electrical Existing enclosures are READ Datasheets ○ ○ abundant ○ Consult Experts Cross-Discipline Design Twice, Build Once ○ ○ knowledge is important Simulate Early, Simulate ○ Use intuition to validate Often ○ simulation results ○ Triple check designs before ordering
Reflect: Lessons Learned ● Computer ● Overall Best Processor != Best Communication with ○ ○ Solution Customer Dev Board vs. Full Frequency ■ ■ Custom Expectations ■ ADC Roulette Get it in Writing ■ ■ ■ PSOC Trap ○ Testing in MSDI SD Cards - Not That Easy Importance of a ○ ■ Prototype
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