Transcript Temperature Sensor EEL 3111 Summer 2003

MSP 430 Project
ECE 300
Spring 2004
William S. McLemore
Ruben D. Briano
Cheng-Han Tsai
Purpose of this Project
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Have an opportunity to work as member of a
team.
Learn basic skills of soldering
Learn to compile program in order to flash
the computer chip
Select and study the characteristic of a sensor
Learn to calibrate the chosen sensor in order
to get accurate readings through the
computer chip and to the LCD
Process of Building the Project
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Solder all components to the board
Test the board by flashing demo file
Create working circuit between board
and sensor
Change and correct the code to display
wanted results
Test sensor and board together in
various cases
Soldering Order
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Surface mounted capacitors and
resistors
Push button switch, voltage regulator, 5
volt input, and slider switch
MSP430 chip
LCD
JTAG connector
Steps for Programming the
MSP430 Chip
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Copy the files from the ECE 300 website
Create a new project in the IAR software
Add the Delay, Demo, and LCD files to the
project
Compile the project and then select the
Debugger
Open the lcdDisplay and select f430p
Now the chip has been flashed and it should
scroll ‘HELLO’ across LCD display.
Choosing a Sensor
Sensor
Linear
Input Output Accuracy
(+/-)
(deg C)

Temp.
Range
(deg C)
AD590
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Voltage Current
0.5
-55 - 150
LM19
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Current Voltage
3.5
-55 - 130
Voltage Voltage
3.0
-40 - 125
Voltage Voltage
1.0
-55 - 125
DS56
AD7818
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AD590 Temperature Sensor
Features
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Linear current output
Wide Temperature Range:
-55°C to 150 °C
4 V to 30 V supply
voltage range allows for
versatility
Very accurate when
compared to other
sensors
Output current is not
dependant on the exact
value of the input voltage;
as long as it is within the
specified range, the
current will be the same
Graph of the Input vs. the Output
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Linear relationship
between the output
current and input
voltage.
Anywhere between
the specified voltage
range, the output
current is proportional
to the temperature in
Kelvin, equal to 1
micro-amp per Kelvin
Schematic of Our First Circuit
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AD590
9V
1Kohm
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Vo
This schematic was
highly unstable
Measured the
correct room
temperature
Jumped around
randomly when an
ice cube was placed
on it, varying
from –20ºC to 58ºC
Schematic of Circuit
1 kOhms
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AD590
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9V
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Vo
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Operating voltage used
for the op amp is 9V
This schematic gave the
most stable results
Gives the room
temperature and went
down to 1ºC when an
ice cube was placed on
it.
The Vo is tied into the
board
Block Diagram
9V
Battery
LCD
Op Amp
And
Resistor
AD590
MSP 430
Intelligent Sensor Microcode
Initializations
Input
Convert data
Send Voltage
MSP 430 Processor
Output
Source Code
sample = ADC12MEM6;
X = sample;
Y = .2*(X+X1+X2+X3+X4);
// moving average filter
X4 = X3;
X3 = X2;
X2 = X1;
X1 = X;
Y = Y – 3756.2;
// Y – offset
Y = Y * 10.1;
lcd_word(Y,2);
lcd_char(0,’C’);
// displays a ‘C’ for Celsius
Complications
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Between the time that we got our board
to flash and connected to our sensor,
some of the pins on the chip came loose,
and we had to re-solder some of the pins.
Our first op amp was bad and gave us
unstable results. We switched it with
another one, which gave us better results.
Picture of the Board and
Circuit
Sources
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Analog Devices:
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http://www.analog.com/
The University of North Florida College
of Computing, Engineering, and
Construction:
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http://www.unf.edu/ccec/