红外壁障传感器制作

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红外壁障传感器制作Dallas Personal Robotics Group
IR Detector
By: Darren Sawicz
Original Documentation By: Jeff Koenig
his document is an update
reflecting the changes made to
Jeff Koenigs Infrared detector circuit.
The assembly code and circuit are
unchanged but the printed circuit
artwork and documentation have
been upgraded to make assembly
easier.
Theory of Operation
The PIC12C509 generates a 38 kHz
square wave， which delivers current
to the infrared LEDs. The infrared
energy is then reflected off of an
obstacle， if present， and is detected
by the Sharp IR receiver.
The program does the following:
1. Flash the 38 kHz square wave
through the Left infrared LED for
600 microseconds.
2. Check the Sharp detector – if it
detects IR light， go to step 3. If not，
go to step X.
3. Good! A reflection was detected.
But， it might be from another source，
so we wi ll turn off the Left LED and
see if the Sharp detector is still
seeing infrared illumination (from
another source).
4. Keep the Left infrared LED off for
600 microseconds.
5. Check the Sharp detector – there
shouldnt be any IR detected， since
we turned off the LED. If there is IR
detected， go to step X，
6. A valid reflection was detected， so
turn on the left LED (red) and bring
header pin 4 high. Skip to step 8.
7. No valid detection was made.
8. Return to step one， but this time
substitute right” for left”
The New Board
The new circuit board is smaller than
Jeff Koenigs original board. Each
new board measures 1.5" x 1". This
allows 16 small boards to be cut
from a single 4" x 6" board.
The original ASCII artwork showed
none of the component connections，
only component layout. I created a
schematic drawing of the circuit to
make it easier to see how the circuit
is connected. The schematic is
included on the last page.
T