Hardware Reference
In-Depth Information
Airflow pipe
connector
AWM3300V
V
OUT
V
CC
GND
Figure E12.16
■
Microbridge AWM3300V
the airfl ow. Its applications include air-conditioning, medical ventilation/anesthesia control,
gas analyzers, gas metering, fume cabinets, and process control. The AWM3300V operates
on a single 10-V
10-mV power supply. The sensor output (from
V
OUT
) corresponding to the
airfl ow rate of 0,1.0 L/min is 1.0 V to 5.0 V. The AWM3300V can operate in the temperature
range of 225 to 85
o
C. It takes 3 ms for the output voltage to settle after power-up. Design a
circuit to measure and display the mass airfl ow using the AWM3300V. Write a program to
confi gure the HCS12 A/D module, start the A/D conversion, and display the mass airfl ow in
an LCD display. Update the display fi ve times per second.
±
L12.1 A/D converter testing.
Perform the following steps.
Step 1
Set the function generator output (in the lab) to between 0 and 5 V.
Step 2
Connect the AN1 pin to the functional generator output. Set the frequency to about
10 kHz.
Step 3
Write a program to perform the following operations:
•
Configure the A/D module properly.
•
Start the A/D conversion.
•
Take 64 samples, convert them, and store the conversion results at appropriate
SRAM locations.
•
Compute the average value and store it in D.
If your demo board has a square waveform output, then select an output with a frequency
close to 16 kHz. Connect it to the AN1 pin.
L12.2 Digital thermometer.
Use the LM34 temperature sensor, the 741 OP Amp, and the re-
quired resistors to construct a digital thermometer. The temperature should be displayed in
three integral and one fractional digit. Use the LCD on your demo board to display the tempera-
ture. Update the temperature once every 200 ms.
L12.3 Barometric pressure measurement.
The Motorola MPX4115A is a pressure sensor that
can measure a pressure ranging from 15 to 115 kPa (2.2 to 16.7 psi) and has a corresponding
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