final presentation - edgeedge.rit.edu/edge/p14452/public/msdii/finalpresentation/msdii final...
TRANSCRIPT
Final PresentationP14452
● 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
BenchmarkingDevice 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 Samples4M 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 MaterialsItem 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 TestingChirp -
w/o RubberEndcaps
Chirp - w/ Rubber Endcaps
Random -w/o Rubber
Endcaps
Random - w/ RubberEndcaps
● 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 FilterVout range 0.25V - VDDVCOM= VDD/2VOUT = (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
ordering
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?