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?