Interface Definitions

Interface Definitions

By Jimmy Fernandez – Systems Engineer

A schematic for the interface definition and a system resource table was generated for the Rover Project.

Schematic

The current schematic shows how the electronic components will be connected.  The illuminator is wired to one of the analog pins on the Uno, so that it can be turned on through code.  It is powered through a 12V external battery source.  It is represented as an LED on the schematic due to the illuminators simple on/off nature.  Note that a diode is connected to the A0 pin so that current feedback does not damage the board.  Each potentiometer is also connected to a 5V power source.  The purpose of the potentiometers is to prevent the pan and tilt functions from going beyond their boundaries.  The driver motors connections mimic that of ROSCO, so that we can use the previous code to drive.  The ROSCO code is tuned for servos, so we will need to rewrite that section and make it compatible with our digital potentiometer and DC motor.  Unfortunately, the Adafruit motor shield diagram is not available yet for Fritzing, so compromise was necessary.  The Samsung Galaxy S3 is represented by the Mystery Part available in Fritzing.  For the uninitiated, the motor shield is simply placed on top of the Arduino while matching the pins for the headers.

UnoShields_schem_1130

Figure 1: Schematic View

UnoShields_bb_1130

Figure 2: Fritzing

System Resource Table:

The following table represents the connection of each pin to the Arduino or Adafruit Motorshield:

A PDF version, ResourceTable.pdf is also available.

This diagram is pretty self-explanatory.  It tells us where each component will be connected in relation to the Arduino and the ATmega328P chip.  Both potentiometers and the illuminator take advantage of analog pins on the board.  All four motors are connected to the Adafruit motor shield.  Of course, the motor shield is attached to the Arduino Uno.  PD1 and PD0 are taken by the USB connection so that the Android phone can transmit data through the serial interface.

pinout

Figure 3: Pinouts