基于PIC16F877A控制boostbuckDCDC变换器

1、. . . 输出电压可设置的升降压DC-DC变换器如下图，设计一个DC-DC变换电路:要求：1）当输入电压Ui 在14V16V变化时，输出电压Uo恒压输出，Uo稳态相对误差不超过2%，Uo可通过键盘设置为1020V间的任意电压，电压步进长度0.1V；2）要求用液晶屏显示输出电压和输出电流，电压显示精度到0.1V，电流显示精度到50mA；要求带4*4键盘，键盘定义如下：123del456自定义789自定义小数点0自定义ok3）输出负载电流I2围01A;4）试计算电源效率。<一>电路部分：设计原理：主电路boost-buck电路，驱动电路，控制电路（pic单片机控制）。原理概述：boo

2、st-buck电路利用开关管的开关，输出电压的平均值Uo=ton/(T-ton)×Ui=D/(1-D)*ui。D为占空比。用单片机输出PWM方波（经过驱动电路放大后）控制MOS管的开关，来调节输出电压。将输出电压送回PIC单片机模数转换模块，通过反馈调节PWM占空比调节电压，使输出稳定。利用差分运放电路，检测出输出电压与输出电流的关系。键盘输入设置电压。外接液晶屏显示输出电压和输出电流和输出电流。主电路：驱动电路：控制电路：液晶外围电路：键盘电路模块：用multisim仿真如下结果：设计小结：输出电流与输出电压的关系U=RI。在程序设计中，通过电压的输出在液晶屏上显示电流的输出。二程

3、序部分：输出pwm：#include<pic.h>unsigned int DRE;_CONFIG(0x2001);void PWM()PR2=39; /频率25KHz TRISC|=0x04; /RC2置为输入 CCP1CON=0X0c; /PWM输出 CCPR1L=0X01; /占空比25% T2CON=0X04; /开定时器TMR2，预分频1：1 TMR2IF=0; /清除TMR2中断标志位void main() while(1) PWM(); DRE=40; /高电平寄存器的值 CCPR1L=DRE/4; /装入高8位 CCP1CON<5>=(DRE/2)%2;

4、 /装入次低位 CCP1CON<4>=DRE%2; /装入最低位 while(TMR2IF=0); TRISC=0x00; AD转换：#include<pic.h>_CONFIG(FOSC_XT&WDTE_OFF&LVP_OFF);void AD() TRISA0=1; /RA1设置为模拟输入 ADCON1=0x00; /参考电压电源电压VDD AD转换周期Fosc/4 ADCON0=0x40; / void delayms(int xms) int i,j ; for(i=0;i<xms;i+) for(j=0;j<150;j+) ; vo

5、id main() unsigned int x,y,z,A,B,C; unsigned int Result,Result1,ADRES; while(1); delayms(5);/采样采样电压充电延时 GO=1; while(GO=1); Result=ADRES; x=(Result*5)/256; /取个位十分位百分位 y=(Result*50)/256)%10; z=(Result*500)/256)%10;Result1=Result/1.2-1.5; A=(Result*5)/256; /取个位十分位百分位 B=(Result*50)/256)%10; C= (Result*5

6、00)/256)%10;液晶屏与键盘：#include<pic.h>#define LCD_EN RC7#define LCD_RW RC6#define LCD_RS RC5unsigned int x,y,z,A,B,C;unsigned char dis0="voltage:"unsigned char dis1='0','1','2','3','4','5','6','7','8','9',

7、9;.'unsigned char dis2="current:"unsigned char dis3='0','1','2','3','4','5','6','7','8','9','.'unsigned char dis43, dis53; _CONFIG(FOSC_XT&WDTE_OFF&LVP_OFF);void delay (int xms) int i,j; for

8、(i=0;i<xms;i+) for(j=0;j<150;j+); void write_() unsigned char ; /声明写指令 LCD_RS=0; LCD_RW=0; LCD_EN=0; PORTD=; delay(5); LCD_EN=1; delay(5); LCD_EN=0;void write_date() unsigned char date; LCD_RS=1; LCD_RW=0; LCD_EN=0; PORTD=date; delay(5); LCD_EN=1; delay(5); LCD_EN=0; void init() TRISD=0x00; TR

9、ISC&=0x1f; write_(0x38); delay(5); write_(0x0c); delay(5); write_(0x06); delay(5); write_(0x01); delay(5); void display() unsigned char j; dis40=dis1x; dis41=dis110; dis42=dis1y; dis43=dis1z; write_(0xc8); for(j=0;j<=3;j+) write_date(dis5j); delay(1); unsigned char k; dis50=dis3A; dis51=dis31

10、0; dis52=dis3B; dis53=dis3C; write_(0xc8); for(k=0;k<=3;k+) write_date(dis4k); delay(1); void main() unsigned char i; init(); write_(0x80); /显示第1行 for(i=0;i<=8;i+) write_date(dis0i); delay(1); write_(0x80+0x40);/显示第2行 for(i=0;i<=8;i+) write_date(dis2i); delay(1); #include<pic.h>#inclu

11、de<pic.h>#define LCD_EN RC7#define LCD_RW RC6#define LCD_RS RC5unsigned int x,y,z,A,B,C;unsigned char dis0="voltage:"unsigned char dis1='0','1','2','3','4','5','6','7','8','9','.'unsigned char dis

12、2="current:"unsigned char dis3='0','1','2','3','4','5','6','7','8','9','.'unsigned char dis43, dis53; _CONFIG(FOSC_XT&WDTE_OFF&LVP_OFF);void delay (int xms) int i,j; for(i=0;i<xms;i+) for(j=0

13、;j<150;j+); void write_() unsigned char ; /声明写指令 LCD_RS=0; LCD_RW=0; LCD_EN=0; PORTD=; delay(5); LCD_EN=1; delay(5); LCD_EN=0;void write_date() unsigned char date; LCD_RS=1; LCD_RW=0; LCD_EN=0; PORTD=date; delay(5); LCD_EN=1; delay(5); LCD_EN=0; void init() TRISD=0x00; TRISC&=0x1f; write_(0x3

14、8); delay(5); write_(0x0c); delay(5); write_(0x06); delay(5); write_(0x01); delay(5); void display() unsigned char j; dis40=dis1x; dis41=dis110; dis42=dis1y; dis43=dis1z; write_(0xc8); for(j=0;j<=3;j+) write_date(dis5j); delay(1); unsigned char k; dis50=dis3A; dis51=dis310; dis52=dis3B; dis53=dis

15、3C; write_(0xc8); for(k=0;k<=3;k+) write_date(dis4k); delay(1); void main() unsigned char i; init(); write_(0x80); /显示第1行 for(i=0;i<=8;i+) write_date(dis0i); delay(1); write_(0x80+0x40);/显示第2行 for(i=0;i<=8;i+) write_date(dis2i); delay(1); #define KEYBOARD_PORT_DIR TRISB /键盘扫描方向端口#define KEY

16、BOARD_PORT PORTB /键盘扫描端口#define NO_KEY 0xFF /无按键_CONFIG(0x3FFF);unsigned char L,O;char scankeypad(); /获取4×4键盘值char getkeyvalue(); /获取某按键的值void delay(int xms)int i,j;for(i=0;i<xms;i+) for(j=0;j<150;j+);const char ccode162= 0xEE,1,0xED,2,0xEB,3,0xE7,'L', 0xDE,4,0xDD,5,0xDB,6, 0xD7,&

17、#39;+', 0xBE,7,0xBD,8, 0xBB,9, 0xB7,'-', 0x7E,'.',0x7D,0,0x7B,'*', 0x77,'O' ;char scankeypad() /获取4*4键盘扫描码char key4H=0,key4L=0,scancode=0;TRISD=0xF0; /低四位输出，高四位输入PORTD=0x00; /低四位输出0asm("nop");asm("nop"); /待输出信号稳定key4H=PORTD; /读取高四位key4H=key4H&a

18、mp;0xF0; /将低四位屏蔽if(key4H!=0xF0) /有按键按下delay(20);key4H=PORTD; /重读if(key4H!=0xF0)TRISD=0x0F;PORTD=0x00;asm("nop");asm("nop");key4L=PORTD; /读取高四位key4L=key4H&0x0F; /将高四位屏蔽if(key4L!=0x0F) /有按键按下scancode=key4H|key4L;/高四位与低四位组成键盘扫描码while(PORTD!=0x0F); /按键未松开等待return(scancode);return NO_KEY;char Getkeyvalue() /获取扫描码 char keyvalue=0,c=0; keyvalue=scankeypad(); if(keyvalue!=NO_KEY) while(keyvalue!=ccodec0) /比较描码与当前数组元素是否相等 c+; return(ccodec1);/返回序号对应值 return(NO_KEY);void main() int i