Parallax 28034 User manual

Web Site: www.parallax.com
Forums: forums.parallax.com
Sales: [email protected]
Technical: [email protected]
Office: [phone]
Fax: [phone]
Sales: [phone]
Tech Support: [phone]
Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 1 of 9
Infrared Line Follower Kit (#28034)
The Infrared Line Follower Kit from Parallax provides eight infrared emitter and receiver pairs for high-
precision line-following applications. Mounting hardware for both the Boe-Bot®and Stingray™robots are
also included for easy startup.
All IR frequency generation is done onboard using an ICM7555 chip, requiring no external signaling. This
allows for simple interfacing to the Infrared Line Follower, since the user only needs to read the state of
each IR receiver to detect white or black surfaces. An “Enable” pin is also included which when pulled low
puts the Infrared Line Follower into low-power mode.
Features
Compatible with both the Boe-Bot and Stingray robots from Parallax
Onboard 3 V regulator for easy use with Propeller-powered robots
Easily adjust 38–43 kHz IR frequency using an onboard potentiometer (See Calibration, page 8)
Onboard LEDs for instant line detection communication
High immunity to ambient lighting conditions
Mounting hardware included
No external signaling required
Key Specifications
Power Requirements: 3.3– 5.5 VDC;
maximum 35 mA working, 30 µA
when disabled
Communication: Single bit high/low
output for each IR emitter/receiver
pair
Operating temp: 32 to 140 °F
(0 to 50 °C)
Dimensions: 3.03 x 1.33 in
(7.7 x 3.4 cm)
Application Ideas
Line following
Maze navigation
Robotic contests
Detect line stripe width
Edge detection

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 2 of 9
Bill of Materials
Part # Quantity Description
- 1 Infrared Line Follower PCB
- 2 10” 4-pin female/female cables
- 1 10” 3-pin female/female cable
- 2 4-pin male/male headers
- 1 3-pin male/male header
710-00007 2 7/8" 4-40 pan-head screws
700-00028 2 1/4" 4-40 pan-head screws
700-00060 2 1" round standoffs
713-00007 2 1/2" round spacers
700-00003 2 4-40 x 3/8" nuts
Additional Items Required
#2 Philips-head screwdriver
Black 3/4" electrical tape
White poster board
Resources and Downloads
Check for the latest version of this document, free software, and example programs from the Infrared
Line Follower Kit product page. Go to www.parallax.com and search 28034.
Theory of Operation
Upon connecting power, the onboard ICM7555 chip begins sending a 38–43 kHz signal through all 8 IR
LEDs. If the IR LED is over a white surface, light is reflected to the IR receiver, and its output is low.
When the IR LED is over a black surface, no light is reflected to the IR receiver, and its output is high.
The voltage regulator included on the PCB limits the power to the Infrared Line Follower’s circuitry to 3 V.
This means that a 5 V supply can safely be used with microcontrollers operating at 3.3 V.
Red LEDs located on the top of the board are wired to the output of each IR receiver, and the anode of
each LED is connected to power. When the IR LED is over a white surface, the low signal completes the
LED circuit and turns the LED on. Conversely, when the IR LED is over a black surface, the LED receives
dual high signals and the LED is off. This allows for easy visual feedback of the Infrared Line Follower’s
output states.
An onboard potentiometer also allows for the easy adjustment of the infrared frequency between 38 and
43 kHz. This allows the sensor to detect different colored lines, and also allows for the easy adjustment
of the sensor to different lighting conditions or mounting positions. For more information on how to
calibrate the sensor, see the Calibration section on page 8.
To isolate each IR senor and prevent false triggering, headers are placed between each IR emitter and
receiver pair.

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 3 of 9
Quick-Start Guide
Before using the Infrared Line Follower, it’s a good idea to test the sensor’s responsiveness in the area
intended for use. This section includes instructions for mounting and testing the Infrared Line Follower on
your Boe-Bot or Stingray robot, as well as for calibrating it in your lighting conditions. In order to use the
example code below, you will need a strip of black electrical tape on white paper.
Boe-Bot Assembly Instructions
To mount the Infrared Line Follower on your Boe-Bot robot, you will need the following materials:
(2) 7/8" 4-40 pan-head screws
(2) 1/4" 4-40 pan-head screws
(2) 1" round standoffs
(2) 1/2" round spacers
Step 1
Insert the 7/8" screws through the top of the Boe-
Bot chassis through the left and right slots at the
front.
Step 2
On the underside of the chassis, slip on the 1/2"
unthreaded spacer on each screw, followed by the
1" standoff. Don’t tighten the standoff completely
to allow for easier alignment of the Infrared Line
Follower’s mounting holes in the next step.

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 4 of 9
Step 3
Align the threaded standoffs with the mounting
holes on the Infrared Line Follower and use the
1/4" screws to secure the sensor to the screws.
The Infrared Line Follower should be facing
downward, with the headers pointing toward the
tail wheel.
Stingray Assembly Instructions
To mount the Infrared Line Follower on your Stingray, you will need the following materials:
(2) 7/8" 4-40 pan-head screws
(2) 1/2" round spacers
(2) 4-40 x 3/8" nuts
Step 1
Remove the front Stingray plate and insert the 7/8"
screws through the top of the chassis through the
front slot.

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 5 of 9
Step 2
On the underside of the chassis, slip on the 1/2"
unthreaded spacer on each screw.
Step 3
Align the screws with the mounting holes on the
Infrared Line Follower and use the nuts to secure
the sensor to the screws. The Infrared Line
Follower should be facing downward, with the
headers pointing toward the tail wheel.
Pin Definitions
Pin Name Type Function
1 GND G Ground -> 0V
2 Vdd P Supply Voltage
3 EN I Enable pin, pull low for low-power mode
4 OUT0 O Output state of IR receiver 0
5 OUT1 O Output state of IR receiver 1
6 OUT2 O Output state of IR receiver 2
7 OUT3 O Output state of IR receiver 3
8 OUT4 O Output state of IR receiver 4
9 OUT5 O Output state of IR receiver 5
10 OUT6 O Output state of IR receiver 6
11 OUT7 O Output state of IR receiver 7
Pin Type: P = Power, G = Ground, I = Input, O = Output

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 6 of 9
Quick-Start Circuit
The circuit pictured can be used with the example code below, as well as for the line following code
included at the end of this document.
Note: In order to use this sensor with the Stingray, you will need to bypass the voltage translators on
the Propeller Robot Control Board. The Infrared Line Follower has a 3 V onboard regulator, and the
Propeller Robot Control Board’s translators will interfere with signals coming from the sensor.
For instructions on how to disable the translators, see the documentation available on the Propeller Robot
Control Board’s product page. Go to www.parallax.com and search 28230.
Figure 1: Infrared Line Follower Quick-Start Circuit
BASIC Stamp 2 Example Code
The program InfraredLineFollower_Simple.bs2 will test the Infrared Line Follower sensors before they’re
used in a line-following application. Follow the instructions below to test that all 8 sensors are working
correctly.
Affix a 3/4" piece of electrical tape on a white piece of paper.
Enter & run InfraredLineFollower_Simple.bs2 (below).
Place sensor S0 over the electrical tape and the other sensors over the white paper.
The Debug Terminal should read %00000001 and the S0 LED should be off.
Repeat this process until all eight sensors are tested.
If your sensor doesn’t display a logical 1 when over a black surface and a logical 0 when over a white
surface, check your connections and/or try adjusting the frequency in the Calibration section on page 8.

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 7 of 9
' InfraredLineFollower_Simple.bs2
' Displays output states of the Infrared Line Follower using the Debug Terminal.
' {$STAMP BS2}
' {$PBASIC 2.5}
state VAR Byte
DO
state = INL ' Read input state of pins 0-7
DEBUG HOME, "state = %", BIN8 state ' Display states on Debug Terminal
LOOP
Propeller P8X32A Example Code
The program below will test the Infrared Line Follower sensors before they’re used in a line-following
application. Follow the instructions below to test that all 8 sensors are working correctly.
Affix a 3/4" piece of electrical tape on a white piece of paper.
Enter & run InfraredLineFollower_Simple.spin.
Place S0 over the electrical tape, and the other sensors over the white paper.
The Parallax Serial Terminal should read %00000001 and the S0 LED should be off.
Repeat this process until all eight sensors are tested.
If your sensor doesn’t display a logical 1 when over a black line and logical 0 when over a white line,
check your connections and/or try adjusting the frequency in the Calibration section on page 8.
'' InfraredLineFollower_Simple.spin
'' Displays output states of the Infrared Line Follower using the Parallax Serial Terminal.
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
VAR
byte state
OBJ
pst : "Parallax Serial Terminal"
PUB Main
outa[0..7]~ ' Sets pins 0-7 as input
pst.start(115_200) ' Initialize Parallax Serial Terminal
waitcnt(clkfreq + cnt)
repeat
state := ina[7..0] ' Read the states of pins 0-7
pst.home ' Set cursor to upper left corner
pst.bin(state, 8) ' Display states in PST
waitcnt(clkfreq/200 + cnt)

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 8 of 9
Calibration
Different lighting conditions, mounting positions or changes in temperature may require different
frequency settings. For this reason, the Infrared Line Follower has a user selectable infrared frequency
range of 38-43 kHz using an onboard potentiometer. If you are having problems reading a line when
running the test code, place all IR detectors over a black surface and gently adjust the onboard
potentiometer until all eight red LEDs are off.
Note: A small flathead screwdriver is required to adjust the frequency range. The Parallax screwdriver
included in the Boe-Bot and Stingray robot kits is usually sufficient.
Boe-Bot Robot Line Following Code
The code below can be used for simple Boe-Bot line following applications, and is compatible with the
circuit shown in Figure 1. Keep in mind that this is not the most robust line following code, which can and
should be expanded to better fit your needs.
' InfraredLineFollower_BoeBot.bs2
' Simple line following Boe-Bot code using the Infrared Line Follower.
' {$STAMP BS2}
' {$PBASIC 2.5}
DO
SELECT INL ' Select line follower states
CASE %11000000, %11100000 ' Pivot right
PULSOUT 13, 650
PULSOUT 12, 650
CASE %01100000, %01110000 ' Curve right
PULSOUT 13, 700
PULSOUT 12, 650
CASE %00110000 ' Slight right
PULSOUT 13, 750
PULSOUT 12, 650
CASE %00111000 ' Adjust right
PULSOUT 13, 800
PULSOUT 12, 650
CASE %00011000 ' Straight
PULSOUT 13, 850
PULSOUT 12, 650
CASE %00011100 ' Adjust left
PULSOUT 13, 850
PULSOUT 12, 700
CASE %00001100 ' Slight left
PULSOUT 13, 850
PULSOUT 12, 750
CASE %00000110, %00001110 ' Curve left
PULSOUT 13, 850
PULSOUT 12, 800
CASE %00000011, %00000111 ' Pivot left
PULSOUT 13, 850
PULSOUT 12, 850
ENDSELECT
LOOP

Copyright © Parallax Inc. Infrared Line Follower Kit (#28034) v1.0 1/18/2011 Page 9 of 9
Stingray Robot Line Following Code
The line following code included below is ideal for longer courses with wide-radius turns, and is
compatible with the circuit shown in Figure 1.
This code was written to be used as a skeleton for higher-precision line following applications using PID
and/or other control algorithms.
'' InfraredLineFollower_Stingray.spin
'' Simple line following code compatible with the Parallax Stingray Robot, best used
'' on longer courses with wide-radius turns
CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
MotorA = 25 ' Motor A connected to P25
MotorB = 26 ' Motor B connected to P26
VAR
byte DutyCycleA, DutyCycleB, state
OBJ
PWM : "PWM_32_V2.spin"
PUB Main
PWM.Start ' Start PWM object
dira[7..0]~ ' Set pins 7..0 as input
repeat
state := ina[7..0] ' Set input states to variable state
case state
%00000011, %00000001, %00000010: ' Pivot left
DutyCycleA := 65
DutyCycleB := 0
%00000111, %00000110, %00000100: ' Slight left
DutyCycleA := 60
DutyCycleB := 0
%00001110, %00001100: ' Adjust left
DutyCycleA := 55
DutyCycleB := 0
%00011100, %00011000, %00111000: ' Straight
DutyCycleA := DutyCycleB := 50
%01110000, %00110000: ' Adjust right
DutyCycleA := 0
DutyCycleB := 55
%11100000, %01100000, %0010000: ' Slight right
DutyCycleA := 0
DutyCycleB := 60
%11000000, %01000000, %10000000: ' Pivot right
DutyCycleA := 0
DutyCycleB := 65
other: ' Anything else, slowly move forward
DutyCycleA := DutyCycleB := 20
PWM.Duty(MotorA, DutyCycleA, 50) ' Adjust motor speeds
PWM.Duty(MotorB, DutyCycleB, 50)

Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Parallax:
28034