1. Microprocessors Tutorial 2: Arduino Robotics

2. Agenda 1. Robot Anatomy 2. Sensor Review 3. PWM 4. MAKE: Fade
5. Motors
6. H Bridge
7. Robot Control library
8. MAKE: Robot react
9. Challenge: Solve Maze
10. Links

3. Robot Anatomy

4. Robot Anatomy

5. Sensor Review Example:
Analog Arduino mapping: 0-5V 
3 connections: V+, pin, GND
Serial Monitor:
Use Serial.begin(9600) to start communication
Use custom function serialOutputValue(“msg”, value) to see sensor value in serial monitor
This robot has IR range sensor:
Outputs V (0-600 in Arduino)
Peaks at 15cm, farther objects create lower voltage
BUT code inverts relationship!
Example:
Example 1 Analog_in

6. Pulse Width Modulation
Duty cycle = percentage of time signal is positive in square wave
Min-Max voltage: 0 – 5v
Min-Max Arduino mapping: 0 – 255
PWM pins have a ~ on Arduino
10% average
50% average
90% average

7. Challenge: Fade Increments
Make: Fade
Use analogWrite(pin, value) to fade light on/off using for loop to vary value
Remember PWM range is 0-255
Recall LED connection:
long leg = positive
small resistor in series necessary
Challenge: Fade Increments
Use PWM to
fade the led from 0 to full in 5 seconds,
hold for 2 secs,
fade back down in 7 seconds.
Then each loop would do it faster and faster or brighter and brighter!

8. Motors
They draw more current than USB/Arduino can supply (40mA per pin, 200mA in total)
so need another power supply: batteries
Current through in 1 direction turns them in 1 direction
More voltage = More speed, how to control voltage?
Use electronically controlled switch (transistor) between motor and batteries
Use PWM pin to control switch
Motors in this robot run on V
and have a peak current of 1A.

9. H- Bridge
Used to make 1 motor turn in either direction by directing current
use 4 switches controlled by 2 signals

10. H- Bridge
The IC we will use (SN754410N) has 2 H-Bridges to control 2 motors
PWM is used here at the enable pin to control speed A

11. Robot Control Library Example:
Written by Sebastien Parent-Charette last year
Get sensor values with
updateSensorRangeState()
And values state_sensor_range_value
Display with serialOutputValue(“msg”, value)
Change directions with
modifyMotorState(motor, direction, speed)
Followed by updateMotorState()
Example:
Example 3: Spin_in_a_Loop

12. MAKE: Robot Move MAKE: Robot React
Change code in Example 3 so you are in control
For example, go forward 5s, stop, turn right 90˚, forward, backwards, left 270 ˚ and come back.
Use modifyMotorState(motor, direction, speed)
updateMotorState()
MAKE: Robot React
When you feel comfortable, add sensor information
Use Example 4: Wall stop, as a base
Get sensor data with updateSensorRangeState()
Use state_sensor_range_value to decide on a move

13. CHALLENGE: solve the maze!
Create your own algorithm to beat the maze using Example 0: Template
Or start from our other example codes
Example 4, 5, 6

14. Useful Links http://www.jeremyblum.com/category/arduino-tutorials/
Arduino Examples
MAKE projects
Jeremy Blum Tutorials (#5: motors and transistors)

15. academics@ieee.concordia.ca ieee.concordia.ca
Questions? Comments? Suggestions?
ieee.concordia.ca