I've built a program to use two lasers and LDR's to control a stepper motor to track the location of a floating weight in a large roto-meter.
The project is fairly simple: A high and low limit switch are mapped during an initialization routine, then the lasers settle on their target. If the target drops lower, the upper sensor gets hit by the laser and commands a stepper to drive down. Inversely, if the target raises, the lower sensor gets hit and commands the stepper to drive up.
Everything works as long as both sensors are blocked at the end of the initialization routine, but if the target is below the top of the meter (which will almost be always), the initialization fails. Attached is my code. I'd appreciate it if somebody could lend a set of eyes. I believe I'm missing something in step 3 of the initialization routine.
///////////////////////////////////////// INITIALIZATION /////////////////////////////////////////
#include <Stepper.h>
#include <Wire.h> // Enable this line if using Arduino Uno, Mega, etc.
#include "Adafruit_LEDBackpack.h"
#include "Adafruit_GFX.h"
Adafruit_7segment matrix1 = Adafruit_7segment();
Adafruit_7segment matrix2 = Adafruit_7segment();
const int sensor_1 = A0; // LDR1. Lower LDR. Added const back to these "read-only" variables
const int sensor_2 = A1; // LDR2 Upper LDR
const int sensor_3 = A2; // Low Limit Switch
const int sensor_4 = A3; // High Limit Switch
int sensorValueA1 = 0; // Lower LDR
int sensorValueA2 = 0; // Upper LDR
int sensorValueA3 = 0;
int sensorValueA4 = 0;
int stepCount = 0;
int LowLimitSwitch = 0;
int HighLimitSwitch = 0;
int LowLimitCount = 0;
int HighLimitCount = 0;
int Percentage = 0;
float voltage = 0;
int LDRvoltage1 = 5; // Set LDRs high so Step 3 of Initialization will track down to find sensor then start LOOP
int LDRvoltage2 = 5;
const int stepsPerRevolution = 200; // change this to fit the number of steps per revolution
// initialize the stepper library on pins 9 through 12
Stepper myStepper (stepsPerRevolution, 9, 11, 10, 12); // Coil energizing sequence (A, A', B, B')
int PWM_out_pin = 3;
int PWM_out_level = 0;
int val = 0;
/////////////////////////////////////// SETUP ///////////////////////////////////////////////////
void setup()
{
matrix1.begin(0x71);
matrix1.setBrightness(15); // set display brightness (1-15)
matrix2.begin(0x72);
matrix2.setBrightness(15); // set display brightness (1-15)
matrix1.println(0, DEC); // initialize the display to show zero
matrix1.writeDisplay();
matrix2.println(0, DEC); // initialize the display to show zero
matrix2.writeDisplay();
myStepper.setSpeed(50); // setting the speed of the stepper
Serial.begin (9600); // initialize the serial port //changed from 57600
pinMode(PWM_out_pin, OUTPUT); // output will be a duty cycle of 0 to 255 with 255 equal to 5v
// initializeSystem(); // Call the system initialization routing from the subrouting area below LOOP
}
///////////////////////////////////// BEGIN LOOP /////////////////////////////////////////////////
void loop()
{
// ================================= Read the Sensors =======================================
sensorValueA1 = analogRead(sensor_1);
sensorValueA2 = analogRead(sensor_2);
LowLimitSwitch = analogRead(sensor_3);
HighLimitSwitch = analogRead(sensor_4);
float LDRvoltage1 = sensorValueA1*(5.0/1023.0); //
float LDRvoltage2 = sensorValueA2*(5.0/1023.0); // This math is required to get divisions of 5v
/*
Serial.print("sensor_1 = "); Serial.print(LDRvoltage1);
Serial.print(" sensor_2 = "); Serial.print(LDRvoltage2);
Serial.print(" LL Switch = "); Serial.print(LowLimitSwitch);
Serial.print(" HL Switch = "); Serial.print(HighLimitSwitch);
Serial.print(" Step Count: "); Serial.print(stepCount);
Serial.print(" LL Count = "); Serial.print(LowLimitCount);
Serial.print(" HL Count = "); Serial.print(HighLimitCount);
Serial.print(" val = "); Serial.print(val);
Serial.print(" "); Serial.print(Percentage); Serial.print("%");
Serial.print(" "); Serial.print(voltage); Serial.println("v");
*/
// ==================================== Main Loop ===========================================
if (((LDRvoltage1)<1.0) && ((LDRvoltage2)>1.0) && ((HighLimitSwitch)<1000)) // Chassis is below target //changed HLSfrom 400 to 1000
{
myStepper.step(1); // Track up (moves 0.5mm per step)
stepCount++; // Increment step count (this is only reliable when moving and incrementing by 1)
delay(10); // Wait for sensors to settle
}
if (((LDRvoltage1)>1.0) && ((LDRvoltage2)<1.0) && ((LowLimitSwitch)<1000)) // Chassis is above target. Stops if it hits the limit switch //changed HLSfrom 400 to 1000
{
myStepper.step(-1); // Track down (moves 1mm per step)
stepCount--; // Decrement step count (this is only reliable when moving and decrementing by 1)
delay(10); // Wait for sensors to settle
}
if (((LDRvoltage1)<1.0) && ((LDRvoltage2)<1.0)) // Chassis is completely OFF target. Run Initialization code to find target again
{
initializeSystem();
}
// Percentage = ((val * 100)/ 255);
// (stepCount * 50 ) / (HighLimitCount / 2)); // Calculate the range percentage. Step count can't exceed 32,767
// ========================== 0 to 5 Volt PWM Output ===========================
int val = stepCount;
val = map(val,(LowLimitCount),(HighLimitCount),0,255);
PWM_out_level = val;
analogWrite(PWM_out_pin, val); // output 0-255 on pin 3 for a duty cycle of 0-5 volts
float voltage = val * (5.0 / 255.0);
Percentage = ((val * 100)/ 255);
// ======================= Print Debugging Information =========================
// Serial.print("sensor_1 = "); Serial.print(LDRvoltage1);
// Serial.print(" sensor_2 = "); Serial.print(LDRvoltage2);
//Serial.print(" LL Switch = "); Serial.print(LowLimitSwitch);
// Serial.print(" HL Switch = "); Serial.print(HighLimitSwitch);
// Serial.print(" Step Count: "); Serial.print(stepCount);
// Serial.print(" LL Count = "); Serial.print(LowLimitCount);
// Serial.print(" HL Count = "); Serial.print(HighLimitCount);
// Serial.print(" val = "); Serial.print(val);
// Serial.print(" "); Serial.print(Percentage); Serial.print("%");
// Serial.print(" "); Serial.print(voltage); Serial.println("v");
matrix1.println(voltage); // display voltage on I2C LED display
matrix1.writeDisplay();
matrix2.println(Percentage); // display percentage on I2C LED display
matrix2.writeDisplay();
delay(1); // this is important for timing so display doesn't lock up
} ///////////////////////////////////// END LOOP /////////////////////////////////////////////////
///////////////////////// FUNCTION SUBROUTINE CALL AREA ///////////////////////////////////////////
void initializeSystem() // Function that runs three steps of system initialization
{
int val = 0; // Set the PWM output to zero volts while the initialization routine is running
// STEP ONE
while (LowLimitSwitch < 400) // Track to the LowLimitSwitch and reset stepCount
{
LowLimitSwitch = analogRead(sensor_3);
myStepper.step(-1); // Track down (moves 0.5mm per step) to find LowLimitSwitch
stepCount--; // Decrement step count (this is only reliable when moving 1 step at a time)
delay(10); // Wait for sensors to settle
}
stepCount = 0; // Reset stepCount
LowLimitCount = stepCount; // Reset LowLimitCount
// STEP TWO
while (HighLimitSwitch < 400) // Track to the HighLimitSwitch and write stepCount into HighLimitCount
{
HighLimitSwitch = analogRead(sensor_4);
myStepper.step(1); // Track up (moves 0.5mm per step) to find HighLimitSwitch
stepCount++; // Increment step count (this is only reliable when moving 1 step at a time)
delay(10); // Wait for sensors to settle
}
HighLimitCount = stepCount; // Write HighLimitCount for Map function to indicate a range position with a voltage
// STEP THREE
while ((sensorValueA1) < 1.0) // Move chassis down until it finds the armature then start Loop //changed from 600 to 1.0
{
sensorValueA1 = analogRead(sensor_1);
myStepper.step(-1); // Track down (moves 0.5mm per step)
stepCount--; // Decrement step count (this is only reliable when moving 1 step at a time)
delay(10);
}
}
