Firmware: Steering calibration

Author: neilpatil-nz

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/global.h

@@ -12,6 +12,7 @@
 #include <avr/io.h>
 #include <stdint.h>
 #include <avr/interrupt.h>
+#include <stdbool.h>
 
 // Global Variables
 #define F_CPU 8000000UL

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/main.c

@@ -35,13 +35,18 @@ int main(void)
 	timer2_init();
 	adc_init();	
 
+	// Sets up PI Controller K values
 	pi_setup();
 
-	calibrate_steering();
+	// Reads and sets up voltage reference values used for steering (Disabled for Proteus)
+	//calibrate_steering(); 
 
-	sei();
+	//****(Enabled for Proteus)
+	min_val = MAX_LIMIT;
+	max_val = MIN_LIMIT;
     while (1) {
-	
+		//****(Enabled for Proteus)
+		calibrate_steering();
 	}
 }
 

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/pi_controller.c

@@ -37,13 +37,13 @@ void pi_controller(){
 	// Sets the duty cycle on IN_1 or IN_2
 	if (set_output > 0){ // Turning Right (positive error)
 		IN_1_OFF;
-		set_duty_cycle(set_output); 
 		IN_2_ON;
+		set_duty_cycle(set_output); 
 	} 
 	else{				// Turning Left (negative error)
 		IN_2_OFF;
-		set_duty_cycle(set_output * (-1)); 
 		IN_1_ON;
+		set_duty_cycle(set_output * (-1)); 
 	}
 }
 

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/pwm.c

@@ -39,7 +39,9 @@ void set_duty_cycle(int16_t value){
 	// Checks which PWM output is ON
 	if(CHECK_IN_1){
 		OCR0A = t_on;// Sets Duty Cycle
+		OCR1A = 0;
 	} else if(CHECK_IN_2){
+		OCR0A = 0;
 		OCR1A = t_on;
 	}
 }

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/steering.c

@@ -8,6 +8,56 @@
 #include "steering.h"
 
 // Finds reference voltage values for each angle
+// Works on two assumptions:
+// - Low voltage = Left, High voltage = Right
+// - Input pins to motor are correctly connected
 void calibrate_steering(){
-	//insert calibration code
+	//  Sets maximum and minimum voltage ranges (Disabled for Proteus)
+	// 	min_val = MAX_LIMIT;
+	// 	max_val = MIN_LIMIT;
+	
+	IN_1_ON; 
+	find_ref();
+	IN_1_OFF;
+	
+	IN_2_ON;
+	find_ref();
+	IN_2_OFF;
+	
+	set_reference_values();
+	
+	//Add straighten wheels function
 }
+
+// Reads and sets maximum and minimum values
+void find_ref(){
+	set_duty_cycle(MAX_LIMIT);
+
+	while(calibration_flag == 0){
+		adc_val = adc_read();
+		if(adc_val < min_val){
+			min_val = adc_val;
+		}
+		else if (adc_val > max_val){
+			max_val = adc_val;
+		}
+		else {
+			calibration_flag = 1; // If steering motor has turned its maximum angle
+		}
+	}
+	calibration_flag = 0; // Clears flag
+}
+
+void set_reference_values(){
+	full_l_turn = min_val;
+	full_r_turn = max_val;
+	
+	// Reference voltage for moving straight
+	straight_turn = (max_val - min_val)/2 + min_val;
+	
+	// Reference voltage for half left turn
+	half_l_turn = (straight_turn - full_l_turn)/2 + full_l_turn;
+	
+	// Reference voltage for half right turn
+	half_r_turn = (full_r_turn - straight_turn)/2 + straight_turn;
+}

Steering/Firmware/Steering_Controller/Steering_Controller/Steering_Controller/steering.h

@@ -11,8 +11,15 @@
 
 #include "global.h"
 #include "adc.h"
+#include "pwm.h"
 #include "led.h"
 
 void calibrate_steering();
+void find_ref();
+void set_reference_values();
+ 
+volatile uint16_t min_val;
+volatile uint16_t max_val;
+volatile uint8_t calibration_flag;
 
 #endif /* STEERING_H_ */