Shopping

Numerous sensors would be needed for the robot to be able to interact with its surroundings in the desired manner. The machine would need to be able to detect obstacles in its environment and avoid them, and identify specific targets and fire on them. The only location to buy Arduino related products in the vicinity was You-Do-It Electronics in Needham, quite a ways a way. While there, an I2C (I-Squared-C) shield was purchased, along with a plug-in proximity sensor (in order to detect obstacles in the environment) and a line sensor (to distinguish between dark and light objects, the basis of the robot's IFF.)

After trying out the devices, it was clear that they may have been somewhat over the caliber of your average student with limited C programming knowledge. Initial attempts to combine the shield sketch with the sensor sketches were unsuccessful, necessitating additional research. An example of the I2C code can be found below.

// by OSEPP <http://www.osepp.com>
// This sketch demonstrates interactions with the IR Proximity Sensor
#include <Wire.h>
// Possible sensor addresses (suffix correspond to DIP switch positions)
#define SENSOR_ADDR_OFF_OFF (0x26)
#define SENSOR_ADDR_OFF_ON (0x22)
#define SENSOR_ADDR_ON_OFF (0x24)
define SENSOR_ADDR_ON_ON (0x20)
// Set the sensor address here
const uint8_t sensorAddr = SENSOR_ADDR_OFF_OFF;
// One-time setup
void setup() {
// Start the serial port for output
Serial.begin(9600);
// Join the I2C bus as master
Wire.begin();
// Turn on the sensor by configuring pin 1 of the GPIO expander to be an
// output pin; the default output value is already HI so there's no need
// to change it
WriteByte(sensorAddr, 0x3, 0xFE); }
// Main program loop
void loop() {
uint8_t val;
// Get the value from the sensor
if (ReadByte(sensorAddr, 0x0, &val) == 0) {
// The second LSB indicates if something was not detected, i.e.,
// LO = object detected, HI = nothing detected
if (val & 0x2) { Serial.println("Nothing detected"); }
else { Serial.println("Object detected"); } }
else { Serial.println("Failed to read from sensor"); }
// Run again in 1 s (1000 ms) delay(1000); }
// Read a byte on the i2c interface
int ReadByte(uint8_t addr, uint8_t reg, uint8_t *data) {
// Do an i2c write to set the register that we want to read from Wire.beginTransmission(addr);
Wire.write(reg);
Wire.endTransmission();
// Read a byte from the device
Wire.requestFrom(addr, (uint8_t)1);
if (Wire.available()) { *data = Wire.read(); }
else {
// Read nothing back
return -1; }
return 0; }
// Write a byte on the i2c interface
void WriteByte(uint8_t addr, uint8_t reg, byte data) {
// Begin the write sequence
Wire.beginTransmission(addr);
// First byte is to set the register pointer
Wire.write(reg);
// Write the data byte
Wire.write(data);
// End the write sequence; bytes are actually transmitted now
Wire.endTransmission();