Buck Converter

1//*************************** Change these values at base of your needs
2  *****************************
3#define VoltageR 9.1f //Voltage to regulate
4
5//
6  Setup of mainboard **********************************************************
7#define
8  convertion 0.1754f //Conversion factor
9
10// Definition of inputs and outputs
11  ********************
12const int uPin = 9; // Control voltage, this is the pin
13  called OC1A
14const int x0Pin = A0;  //Voltage at the output of the second integrator
15
16//
17  Variables to signal feedback *************************
18float FB = 0; // Feedback
19  signal
20float RV = 0; // Reference Voltage
21int e = 0;    // Error variable
22float
23  Switch_cycle = 0; //Dute Cycle
24
25// Variables to time operations **************************
26unsigned
27  long softStart = 500;
28
29void setup() {
30
31  //******************** Set
32  all inputs and outputs **********************************************************
33
34  pinMode(uPin,OUTPUT); // Set pin OC1A as output 
35  pinMode(13,OUTPUT);   //
36  To indicate the device is operate
37  
38  //******************** Set and Clear
39  initial ***************************************************
40  digitalWrite(13,LOW);
41  // Start Led Off 
42  
43  //******************** Calculate all conversions **********************************************************
44
45  RV = (VoltageR*convertion*1024/5); //Convert voltage reference to conversion ADC
46  value 
47  
48  //******************* Delay before start operation ********************************************************
49  
50  SoftStartDelay();
51  
52  noInterrupts(); // disable all interrupts while
53  do configure
54  // ******************************* Set PWM frecuency **********************************************
55
56  // Freq_PWM = 16Mhz /128 = 125 Khz 
57  TCCR1A = (1<<COM1A1) | (0<<COM1A0) |
58  (0<<COM1B1) | (0<<COM1B0) | (1<<WGM11) | (0<<WGM10);   
59  //       COM1A1 = 1
60  ; COM1A0 = 0 ; COM1B1 = 0  ; COM1B0 = 0  ;         Note: When use a inverted output,
61  you must set COM1A1 & COM1A0, if you use a normal output, you only have to must
62  COM1A1
63  //       Clear output OC1A when match happen, Output OC1B disconnected
64
65  TCCR1B = (0<<ICNC1) | (0<<ICES1) | (1<<WGM13) | (1<<WGM12) | (0<<CS12) | (0<<CS11)
66  | (1<<CS10);
67
68  //        ICNC1 & ICES1 are used when Timer had a external
69  signal. Unused in Fast PWM mode
70  //        CS12 = 0; CS11 = 0; CS10 = 0; Select
71  no prescaler
72  //        WGM13 = 1 ; WGM12 = 1;  WGM11 = 1 ; WGM10 = 0; Select
73  Fast 8 bit PWM with TOP value on ICR1
74  
75  ICR1H  = 0x00;  //Set ICR1 register
76  to 80h (#128) MSB = 0x00, LSB = 80h
77  ICR1L  = 0x80;  //This value is TOP of
78  the counter. Timer reach to zero when count is equal to it.
79  
80  TCNT1H =
81  0x00; //Reset MSB of the timer
82  TCNT1L = 0x00; //Reset LSM of the timer
83
84  OCR1AH = 0x00; //Clear MSB of the match register, unused in Fast PWM 8 bit
85
86  OCR1AL = 0x00; //Set zero to start device off, it register is used to change dute
87  cycle
88
89  // ****************************** Set interrup by timer 2 ******************************************
90
91  // T = (1/16MHz)*(2^8-00)*8 = 128 uS
92  TCCR2A = (0<<COM2A1) | (0<<COM2A0) |
93  (0<<COM2B1) | (0<<COM2B0) | (0<<WGM21) | (0<<WGM20);   
94  //       COM1A1 = 0
95  ; COM1A0 = 0  ; COM1B1 = 0  ; COM1B0 = 0  ;  
96  //       OC12A and OC2B both
97  are disconnected
98  
99  TCCR2B = (0<<WGM22) | (0<<CS22) | (1<<CS21) | (0<<CS20);
100
101  //        CS22 = 0; CS21 = 1; CS20 = 0; Select prescaler Fosc/8
102  //        WGM13
103  = 0 ; WGM12 = 0;  WGM11 = 0 ; WGM10 = 0; Select Normal Mode operation
104
105  TCNT2
106  = 0x00; //This register have a pre-load of the timer. However, in this case, it's
107  no have pre-load
108  OCR2A = 0x00; //Clear match register. It's unused
109  OCR2B
110  = 0x00; //Clear match register. It's unused
111
112  TIMSK2 = (0<<OCIE2B) | (0<<OCIE2A)
113  | (1<<TOIE2); // enable timer2 overflow interrupt
114  // ******************************
115  End of the configurate *******************************************
116  interrupts();
117  // enable all interrupts
118}
119ISR(TIMER2_OVF_vect) // interrupt service routine
120  
121{
122  FB = (float)(analogRead(x0Pin));          //Feedback signal
123
124  float
125  k = 0.08;                           //Gain in close loop
126  e = RV-FB;                                //Error
127
128  Switch_cycle = Switch_cycle + e*k;        //Control
129  if(Switch_cycle<=0)                       //Min
130  duty Cycle = 0
131    Switch_cycle = 0;
132  if(Switch_cycle>=122)                     //Mx
133  duty Cycle = 95% ;(122/128)*100 = 95.31% real value
134    Switch_cycle = 122;
135
136    OCR1AL = (unsigned char)(Switch_cycle); //Write duty cycle
137}
138void SoftStartDelay()
139  // Delay with interval of 500ms before start regulation
140{
141  delay(softStart);
142
143  digitalWrite(13,HIGH);  
144}
145void loop() {
146  // put your main code here,
147  to run repeatedly:
148
149}
150

1//*************************** Change these values at base of your needs  *****************************
2#define VoltageR 9.1f //Voltage to regulate
3
4//  Setup of mainboard **********************************************************
5#define  convertion 0.1754f //Conversion factor
6
7// Definition of inputs and outputs  ********************
8const int uPin = 9; // Control voltage, this is the pin  called OC1A
9const int x0Pin = A0;  //Voltage at the output of the second integrator
10
11//  Variables to signal feedback *************************
12float FB = 0; // Feedback  signal
13float RV = 0; // Reference Voltage
14int e = 0;    // Error variable
15float  Switch_cycle = 0; //Dute Cycle
16
17// Variables to time operations **************************
18unsigned  long softStart = 500;
19
20void setup() {
21
22  //******************** Set  all inputs and outputs **********************************************************
23  pinMode(uPin,OUTPUT); // Set pin OC1A as output 
24  pinMode(13,OUTPUT);   //  To indicate the device is operate
25  
26  //******************** Set and Clear  initial ***************************************************
27  digitalWrite(13,LOW);  // Start Led Off 
28  
29  //******************** Calculate all conversions **********************************************************
30  RV = (VoltageR*convertion*1024/5); //Convert voltage reference to conversion ADC  value 
31  
32  //******************* Delay before start operation ********************************************************  
33  SoftStartDelay();
34  
35  noInterrupts(); // disable all interrupts while  do configure
36  // ******************************* Set PWM frecuency **********************************************
37  // Freq_PWM = 16Mhz /128 = 125 Khz 
38  TCCR1A = (1<<COM1A1) | (0<<COM1A0) |  (0<<COM1B1) | (0<<COM1B0) | (1<<WGM11) | (0<<WGM10);   
39  //       COM1A1 = 1  ; COM1A0 = 0 ; COM1B1 = 0  ; COM1B0 = 0  ;         Note: When use a inverted output,  you must set COM1A1 & COM1A0, if you use a normal output, you only have to must  COM1A1
40  //       Clear output OC1A when match happen, Output OC1B disconnected
41  TCCR1B = (0<<ICNC1) | (0<<ICES1) | (1<<WGM13) | (1<<WGM12) | (0<<CS12) | (0<<CS11)  | (1<<CS10);
42
43  //        ICNC1 & ICES1 are used when Timer had a external  signal. Unused in Fast PWM mode
44  //        CS12 = 0; CS11 = 0; CS10 = 0; Select  no prescaler
45  //        WGM13 = 1 ; WGM12 = 1;  WGM11 = 1 ; WGM10 = 0; Select  Fast 8 bit PWM with TOP value on ICR1
46  
47  ICR1H  = 0x00;  //Set ICR1 register  to 80h (#128) MSB = 0x00, LSB = 80h
48  ICR1L  = 0x80;  //This value is TOP of  the counter. Timer reach to zero when count is equal to it.
49  
50  TCNT1H =  0x00; //Reset MSB of the timer
51  TCNT1L = 0x00; //Reset LSM of the timer
52  OCR1AH = 0x00; //Clear MSB of the match register, unused in Fast PWM 8 bit
53  OCR1AL = 0x00; //Set zero to start device off, it register is used to change dute  cycle
54
55  // ****************************** Set interrup by timer 2 ******************************************
56  // T = (1/16MHz)*(2^8-00)*8 = 128 uS
57  TCCR2A = (0<<COM2A1) | (0<<COM2A0) |  (0<<COM2B1) | (0<<COM2B0) | (0<<WGM21) | (0<<WGM20);   
58  //       COM1A1 = 0  ; COM1A0 = 0  ; COM1B1 = 0  ; COM1B0 = 0  ;  
59  //       OC12A and OC2B both  are disconnected
60  
61  TCCR2B = (0<<WGM22) | (0<<CS22) | (1<<CS21) | (0<<CS20);
62  //        CS22 = 0; CS21 = 1; CS20 = 0; Select prescaler Fosc/8
63  //        WGM13  = 0 ; WGM12 = 0;  WGM11 = 0 ; WGM10 = 0; Select Normal Mode operation
64
65  TCNT2  = 0x00; //This register have a pre-load of the timer. However, in this case, it's  no have pre-load
66  OCR2A = 0x00; //Clear match register. It's unused
67  OCR2B  = 0x00; //Clear match register. It's unused
68
69  TIMSK2 = (0<<OCIE2B) | (0<<OCIE2A)  | (1<<TOIE2); // enable timer2 overflow interrupt
70  // ******************************  End of the configurate *******************************************
71  interrupts();  // enable all interrupts
72}
73ISR(TIMER2_OVF_vect) // interrupt service routine  
74{
75  FB = (float)(analogRead(x0Pin));          //Feedback signal
76
77  float  k = 0.08;                           //Gain in close loop
78  e = RV-FB;                                //Error
79  Switch_cycle = Switch_cycle + e*k;        //Control
80  if(Switch_cycle<=0)                       //Min  duty Cycle = 0
81    Switch_cycle = 0;
82  if(Switch_cycle>=122)                     //Mx  duty Cycle = 95% ;(122/128)*100 = 95.31% real value
83    Switch_cycle = 122;
84    OCR1AL = (unsigned char)(Switch_cycle); //Write duty cycle
85}
86void SoftStartDelay()  // Delay with interval of 500ms before start regulation
87{
88  delay(softStart);
89  digitalWrite(13,HIGH);  
90}
91void loop() {
92  // put your main code here,  to run repeatedly:
93
94}
95