pcf8951得到的val沒法和我設(shè)置的值比較大小該怎么修改。怎么用鍵盤設(shè)置檢測(cè)的電壓上下限范圍？
#include <reg52.h>
#include <intrins.h>
#define LCD1602_DB P0
#define uint unsigned int
#define uchar unsigned char
sbit LCD1602_RS=P2^0;
sbit LCD1602_RW=P2^1;
sbit LCD1602_E=P2^2;
void LcdWaitReady() //等待液晶準(zhǔn)備好
{
unsigned char sta;
LCD1602_DB = 0xFF;
LCD1602_RS = 0;
LCD1602_RW = 1;
do
{
LCD1602_E = 1;
sta = LCD1602_DB; //讀取狀態(tài)字
LCD1602_E = 0;
} while (sta & 0x80); //bit7等于1表示液晶正忙，重復(fù)檢測(cè)直到其等于0為止
}
void LcdWriteCmd(unsigned char cmd) //寫入命令函數(shù)
{
LcdWaitReady();
LCD1602_RS = 0;
LCD1602_RW = 0;
LCD1602_DB = cmd;
LCD1602_E = 1;
LCD1602_E = 0;
}
void LcdWriteDat(unsigned char dat) //寫入數(shù)據(jù)函數(shù)
{
LcdWaitReady();
LCD1602_RS = 1;
LCD1602_RW = 0;
LCD1602_DB = dat;
LCD1602_E = 1;
LCD1602_E = 0;
}
void LcdShowStr(unsigned char x, unsigned char y, const unsigned char *str) //顯示字符串，屏幕起始坐標(biāo)(x,y)，字符串指針str
{
unsigned char addr;
//由輸入的顯示坐標(biāo)計(jì)算顯示RAM的地址
if (y == 0)
addr = 0x00 + x; //第一行字符地址從0x00起始
else
addr = 0x40 + x; //第二行字符地址從0x40起始
//由起始顯示RAM地址連續(xù)寫入字符串
LcdWriteCmd(addr | 0x80); //寫入起始地址
while (*str != '\0') //連續(xù)寫入字符串?dāng)?shù)據(jù)，直到檢測(cè)到結(jié)束符
{
LcdWriteDat(*str);
str++;
}
}
void LcdInit() //液晶初始化函數(shù)
{
LcdWriteCmd(0x38); //16*2顯示，5*7點(diǎn)陣，8位數(shù)據(jù)接口
LcdWriteCmd(0x0C); //顯示器開，光標(biāo)關(guān)閉
LcdWriteCmd(0x06); //文字不動(dòng)，地址自動(dòng)+1
LcdWriteCmd(0x01); //清屏
}
/***********************I2C.c文件程序源代碼*************************/
#include <reg52.h>
#include <intrins.h>
#define I2CDelay() {_nop_();_nop_();_nop_();_nop_();}
sbit I2C_SCL = P3^7;
sbit I2C_SDA = P3^6;
void I2CStart() //產(chǎn)生總線起始信號(hào)
{
I2C_SDA = 1; //首先確保SDA、SCL都是高電平
I2C_SCL = 1;
I2CDelay();
I2C_SDA = 0; //先拉低SDA
I2CDelay();
I2C_SCL = 0; //再拉低SCL
}
void I2CStop() //產(chǎn)生總線停止信號(hào)
{
I2C_SCL = 0; //首先確保SDA、SCL都是低電平
I2C_SDA = 0;
I2CDelay();
I2C_SCL = 1; //先拉高SCL
I2CDelay();
I2C_SDA = 1; //再拉高SDA
I2CDelay();
}
bit I2CWrite(unsigned char dat) //I2C總線寫操作，待寫入字節(jié)dat，返回值為應(yīng)答狀態(tài)
{
bit ack; //用于暫存應(yīng)答位的值
unsigned char mask; //用于探測(cè)字節(jié)內(nèi)某一位值的掩碼變量
for (mask=0x80; mask!=0; mask>>=1) //從高位到低位依次進(jìn)行
{
if ((mask&dat) == 0) //該位的值輸出到SDA上
I2C_SDA = 0;
else
I2C_SDA = 1;
I2CDelay();
I2C_SCL = 1; //拉高SCL
I2CDelay();
I2C_SCL = 0; //再拉低SCL，完成一個(gè)位周期
}
I2C_SDA = 1; //8位數(shù)據(jù)發(fā)送完后，主機(jī)釋放SDA，以檢測(cè)從機(jī)應(yīng)答
I2CDelay();
I2C_SCL = 1; //拉高SCL
ack = I2C_SDA; //讀取此時(shí)的SDA值，即為從機(jī)的應(yīng)答值
I2CDelay();
I2C_SCL = 0; //再拉低SCL完成應(yīng)答位，并保持住總線
return (~ack); //應(yīng)答值取反以符合通常的邏輯：0=不存在或忙或?qū)懭胧。?=存在且空閑或?qū)懭氤晒?br />
}
unsigned char I2CReadNAK() //I2C總線讀操作，并發(fā)送非應(yīng)答信號(hào)，返回值為讀到的字節(jié)
{
unsigned char mask;
unsigned char dat;
I2C_SDA = 1; //首先確保主機(jī)釋放SDA
for (mask=0x80; mask!=0; mask>>=1) //從高位到低位依次進(jìn)行
{
I2CDelay();
I2C_SCL = 1; //拉高SCL
if(I2C_SDA == 0) //讀取SDA的值
dat &= ~mask; //為0時(shí)，dat中對(duì)應(yīng)位清零
else
dat |= mask; //為1時(shí)，dat中對(duì)應(yīng)位置1
I2CDelay();
I2C_SCL = 0; //再拉低SCL，以使從機(jī)發(fā)送出下一位
}
I2C_SDA = 1; //8位數(shù)據(jù)發(fā)送完后，拉高SDA，發(fā)送非應(yīng)答信號(hào)
I2CDelay();
I2C_SCL = 1; //拉高SCL
I2CDelay();
I2C_SCL = 0; //再拉低SCL完成非應(yīng)答位，并保持住總線
return dat;
}
unsigned char I2CReadACK() //I2C總線讀操作，并發(fā)送應(yīng)答信號(hào)，返回值為讀到的字節(jié)
{
unsigned char mask;
unsigned char dat;
I2C_SDA = 1; //首先確保主機(jī)釋放SDA
for (mask=0x80; mask!=0; mask>>=1) //從高位到低位依次進(jìn)行
{
I2CDelay();
I2C_SCL = 1; //拉高SCL
if(I2C_SDA == 0) //讀取SDA的值
dat &= ~mask; //為0時(shí)，dat中對(duì)應(yīng)位清零
else
dat |= mask; //為1時(shí)，dat中對(duì)應(yīng)位置1
I2CDelay();
I2C_SCL = 0; //再拉低SCL，以使從機(jī)發(fā)送出下一位
}
I2C_SDA = 0; //8位數(shù)據(jù)發(fā)送完后，拉低SDA，發(fā)送應(yīng)答信號(hào)
I2CDelay();
I2C_SCL = 1; //拉高SCL
I2CDelay();
I2C_SCL = 0; //再拉低SCL完成應(yīng)答位，并保持住總線
return dat;
}
/***********************main.c文件程序源代碼*************************/
#include <reg52.h>
bit flag300ms = 1; //300ms定時(shí)標(biāo)志
unsigned char T0RH = 0; //T0重載值的高字節(jié)
unsigned char T0RL = 0; //T0重載值的低字節(jié)
unsigned char GetADCValue(unsigned char chn);
void ValueToString(unsigned char *str, unsigned char val);
void ConfigTimer0(unsigned int ms);
extern void LcdInit();
extern void LcdShowStr(unsigned char x, unsigned char y, const unsigned char *str);
extern void I2CStart();
extern void I2CStop();
extern unsigned char I2CReadACK();
extern unsigned char I2CReadNAK();
extern bit I2CWrite(unsigned char dat);
void main ()
{
unsigned char val;
unsigned char str[10];
EA = 1; //開總中斷
ConfigTimer0(10); //配置T0定時(shí)10ms
LcdInit(); //初始化液晶
LcdShowStr(2,0, "Volt Volt"); //顯示通道指示
while(1)
{
if (flag300ms)
{
flag300ms = 0;
//顯示通道3的電壓
val = GetADCValue(3); //獲取ADC通道3的轉(zhuǎn)換值
ValueToString(str, val); //轉(zhuǎn)為字符串格式的電壓值
if(val<1.2)
LcdShowStr(2,1, "Low ");
else if(val>=1.2&&val<=2.1)
LcdShowStr(2, 1, str); //顯示到液晶上
else
LcdShowStr(2,1, "High");
val = GetADCValue(0); //獲取ADC通道0的轉(zhuǎn)換值
ValueToString(str, val); //轉(zhuǎn)為字符串格式的電壓值
if(str[0]==str[5]||str[0]==str[6])
LcdShowStr(9, 1, str); //顯示到液晶上
else
LcdShowStr(9,1, "High");
}
}
}
unsigned char GetADCValue(unsigned char chn) //讀取當(dāng)前的ADC轉(zhuǎn)換值，chn為ADC通道號(hào)0-3
{
unsigned char val;
I2CStart();
if (!I2CWrite(0x48<<1)) //尋址PCF8591，如未應(yīng)答，則停止操作并返回0
{
I2CStop();
return 0;
}
I2CWrite(0x40|chn); //寫入控制字節(jié)，選擇轉(zhuǎn)換通道
I2CStart();
I2CWrite((0x48<<1)|0x01); //尋址PCF8591，指定后續(xù)為讀操作
I2CReadACK(); //先空讀一個(gè)字節(jié)，提供采樣轉(zhuǎn)換時(shí)間
val = I2CReadNAK(); //讀取剛剛轉(zhuǎn)換完的值
I2CStop();
return val;
}
void ValueToString(unsigned char *str, unsigned char val) //ADC轉(zhuǎn)換值轉(zhuǎn)為實(shí)際電壓值的字符串形式
{
val = (val*25) / 255; //電壓值=轉(zhuǎn)換結(jié)果*2.5V/255
str[0] = (val/10) + '0'; //整數(shù)位字符
str[1] = '.'; //小數(shù)點(diǎn)
str[2] = (val%10) + '0'; //小數(shù)位字符
str[3] = 'V'; //電壓?jiǎn)挝?br />
str[4] = '\0'; //結(jié)束符
str[5]='1'; //設(shè)置通道3電壓上限
str[6]='0'; //設(shè)置通道3電壓下限
}
void ConfigTimer0(unsigned int ms) //T0配置函數(shù)
{
unsigned long tmp;
tmp = 11059200 / 12; //定時(shí)器計(jì)數(shù)頻率
tmp = (tmp * ms) / 1000; //計(jì)算所需的計(jì)數(shù)值
tmp = 65536 - tmp; //計(jì)算定時(shí)器重載值
tmp = tmp + 12; //修正中斷響應(yīng)延時(shí)造成的誤差
T0RH = (unsigned char)(tmp >> 8); //定時(shí)器重載值拆分為高低字節(jié)
T0RL = (unsigned char)tmp;
TMOD &= 0xF0; //清零T0的控制位
TMOD |= 0x01; //配置T0為模式1
TH0 = T0RH; //加載T0重載值
TL0 = T0RL;
ET0 = 1; //使能T0中斷
TR0 = 1; //啟動(dòng)T0
}
void InterruptTimer0() interrupt 1 //T0中斷服務(wù)函數(shù)
{
static unsigned char tmr300ms = 0;
TH0 = T0RH; //定時(shí)器重新加載重載值
TL0 = T0RL;
tmr300ms++;
if (tmr300ms >= 30) //定時(shí)300ms
{
tmr300ms = 0;
flag300ms = 1;
}
}
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