Sponsored by Phonon CorpAdvisor: Professor Tehranipoor

Colin Gladding (EE)Harpreet Mankoo (EE)

Joe Mascola (EE)

Design SpecificationsPhonon Corporation: developer of Surface Acoustic Wave (SAW) devices for military applications

These SAW devices are sensitive to temperature changes

Our goal:to design/implement the third generation temperature controller for these SAW devices

Third generation will allow programming of parameters without physical deconstruction while still able to fit the generation 2 footprint (shown here)

Design Specs Cont. 2 modules:

Controller itself Programmer

Programmer User interface using RS232 communication

protocol Utilization of dsPic’s onboard flash memory +/- 10 volts to power Sends parameters to and powers controller

Controller Full military temperature range of -55 to 125 °C PID Control loop Feedback from thermistor algorithm PWM from output Fits 4 pin footprint: single wire communication and power

Coding/Software

Loop

yes no

Programmer Hardware

Controller Hardware

Design: Control Loop

Temp SetpointKi Kp freq

Digital PWM Output

MOSFET and heater

Current Temp Sensor

PI Controller

Controller PID System Use of proportional and integral components of typical PID

control system Configured within the microcontroller Parameter efficiency depends

on specific applicationsHas to be tuned for optimum

efficiency by user Ziegler-Nichols tuning method

Flash Memory Our dsPic has 12 Kbytes on-chip Flash program space Stores user defined control system parameters

Kp (proportional constant) Ki (integral constant) Setpoint Temperature

Run Time Self Programming (RTSP) Performed by software using special table write/read

instructions may erase program memory 32 instructions (96 bytes) at a time can write program memory data 32 instructions (96 bytes) at a time.

Design: Thermistor Algorithm Nonlinear relationship between temperature and resistance Plot derived from resistance vs temperature table supplied

by Phonon. Algorithm from

regression analysisR vs T

-55

-5

45

95

145

-92 8 108 208 308 408 508 608

r

t

Testing: Data Transmission

Rise time

Data

(shifted for clarity)

Data

Data

(zoom for emphasis on delay)

Data Transmission Cont. Data with heater attached

Testing:

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8

Time (minutes)

Tem

pera

ture

(deg

rees

C)

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Time (minutes)

Tem

pera

ture

(deg

rees

C)

Setpoint = 53°C, room temperature

Setpoint = 65°C, room temperature

Testing:

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Temperature (degrees C)

Time (minutes)

Setpoint = 78°C, room temperature

Testing:

Overshoot and settling time comparison for various values for Kp and Ki

Controller PCB

Conclusions:

Surface acoustic wave (SAW) devices are signal processing microcircuits which require stable temperature conditions for predictable functionality, and which are typically employed in aerospace applications. Our team, sponsored by Phonon Corporation, has designed and constructed a digital temperature controller device which improves on Phonon's previous-generation device with single-wire programming and precise PID temperature control, while still operating on a minimal four-pin footprint. This design no longer requires expensive and time-consuming alterations of the physical circuit whenever new settings are desired; rather, it facilitates serial digital programming through the controller's existing power supply pin.

Budget: ITEM QTY DESCRIPTION UNIT PRICE SUBTOTAL

1 5 88K3883 MICROCHIP DSPIC30F2020-30I/SP $5.81 $29.05

2 1 16M5244 MICROCHIP AC244002 High Speed Driver $159.98 $159.98

3 1 16M6059 MICROCHIP DV244005 ICE and STD Driver $499.98 $499.98

4 1 92C5431 MICROCHIP SW006012 C-Compiler $895.00 $895.00

5 1 98M0791 MICROCHIP DV243003 I2C Serial Read / Write $79.98 $79.98

6 2 26M9183 MICROCHIP DM300023 SMPS Demo Board $149.99 $299.98

7 2 39M8082 MICROCHIP DM300027 28-Pin Demo Board $79.99 $159.98

8 10 62K0579 MICROCHIP 24LC16B-I/P Memory $0.32 $3.20

9 10 38C8727 Molex multipole connector female $0.19 $1.89

10 10 97B2624 Molex multipole connector male $0.18 $1.78

Total$2,130.82

Our Timeline:SEP OCT NOV DEC JAN FEB MAR APR MAY

Research/Planning

PrototypeDesign

Integrate Design

System Testing

Final Deliverables