Building a Sonar System
VCC
.1uF
VCC
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7
6 TX
5 RX
4 AN
3 PW
2 BW
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1K
VDD
VSS
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RA5
RA0
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LM324
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RA2
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10
RC5
RC0
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RC4
RC1
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8
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RC3
RC2
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1uF
PIC16F676
S-TXR
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LM324
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.1uF
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680pF
SCHEMATIC 1. This is presented for your viewing pleasure. Its
real purpose is to provide some advanced insight as to how
the ultrasonic transducer is supported and nothing more.
the LV-MaxSonar-EZ0 through to the LV-MaxSonar-EZ4.
I’m anxious to begin our MaxBotix sonar project.
However, before we can run the range, we have to learn
how to ride.
The MaxBotix LV-MaxSonar
Ultrasonic Rangefinder
I seriously considered removing the MaxSonar-UT
ultrasonic rangefinder from the EZ0 you see in Photo 1
so that you could see its circuitry. Rather than taking a
chance on ruining my only one, I decided to show you
what the circuitry looks like schematically. Take a look at
Schematic 1. The EZ0 is under the control of a PIC16F676.
Since we don’t really know what the PIC is doing
programmatically, we can only take a guess as to what
the supporting circuitry is doing. If you take a look at the
MaxBotix forum, you’ll see that some students have
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1
6
D1A D1C
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5
D2C D4C
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4
D3C D3A
BAV99DW
VCC
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100K
.01uF
VCC
.1uF
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3
+
1
2
-
LM324
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680pF
attempted to simulate the circuit you see in Schematic 1.
That’s nice. However, MaxBotix wants to keep their secret
formula for ultrasonic sensing under wraps. I respect that
PHOTO 2. It doesn’t get
any better than this.
Each LV-MaxSonar-EZ0
I/O pin is clearly
marked. The black dot
is a color code that
identifies this unit as an
LV-MaxSonar-EZ0. The
LV-MaxSonar-EZ4 has a
yellow dot. I’m always
interested in looking at
printed circuit board
land patterns as you
never know what you
may find. Can you find
other “messages” in
this image?
SERVO 06.2008 43
