Arduino connections

Image from arduino.cc and blog.huntgang

Component	Pin
Front Left Encoder	D2
Front Right Encoder	D3
Back Left Encoder	D5
Back Right Encoder	D6
Throttle (from RC receiver channel 2)	D7
Steering (from RC receiver channel 1)	D8
Electronic Speed Control (for 3-phase Motor)	D10
Servo	D11
Front Ultrasound	D14 = A0
Back Ultrasound	D15 = A1
Right Ultrasound	D16 = A2
Left Ultrasound	D17 = A3

___ ## ROS communication test To ensure that ROS master can communicate with the arduino node, run the following commands in separate terminal windows ``` roscore rosrun rosserial_python serial_node.py ``` Your terminal should output connection information similar to the following. If you see any error messages, then something is wrong with the connection, try reflashing the arduino

(barc)odroid@odroid:~$ rosrun rosserial_python serial_node.py

[INFO] [WallTime: 1469676336.827668] ROS Serial Python Node

[INFO] [WallTime: 1469676336.843514] Connecting to /dev/ttyUSB0 at 57600 baud

[INFO] [WallTime: 1469676339.335939] Note: publish buffer size is 280 bytes

[INFO] [WallTime: 1469676339.338132] Setup publisher on encoder [barc/Encoder]

[INFO] [WallTime: 1469676339.346496] Setup publisher on rc_inputs [barc/ECU]

[INFO] [WallTime: 1469676339.358420] Setup publisher on ultrasound [barc/Ultrasound]

[INFO] [WallTime: 1469676339.374436] Note: subscribe buffer size is 280 bytes

[INFO] [WallTime: 1469676339.376341] Setup subscriber on ecu_pwm [barc/ECU]

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Notes

• The ultrasound sensor code is commented out. Uncomment it when the sensors have been connected, otherwise serial communication may not work properly
• Encoders now use software interrupts (formerly hardware interrupts. Install the necessary library by running source ~/barc/scripts/install_enable_interrupt.sh
• The arduino sends commands to the servo and motor using pulse width modulation. These commands are sent using the write(pwm_angle) and writemicroSeconds(us) member functions of a Servo object. Refer to this article for more clarification on these functions