数字传感器测温-第2页回答

数字传感器测温

2019-07-25 15:41发布

站内问答 / TI MCU

3030 11

本帖最后由 yuluabc 于 2015-9-9 14:43 编辑

各位大神帮忙分析下程序，为什么读出来的温度值总是一个，而且是个负值，百思不得解，谢谢了！

//*****************************************************************************
// MSP430x42x0 Demo - SD16_A, LCD
//*****************************************************************************
//MLX90614 Pin Config
//GND-----6.0.....I/O supply the MLX90614
//SDA-----6.1
//SCL-----6.2
//POW-----6.3.....I/O supply the MLX90614
#include <msp430x54x.h>
#include <string.h>
#include "lcdoperate.h"
#include <math.h>
unsigned int A1,A2,A3,A4,A5;
//*************************************************************
//*************************************************************
#define uchar unsigned char
#define uint unsigned int
void Delay(unsigned int n);
void start_bit();
void stop_bit();
void send_bit(unsigned char bit_out);
unsigned char receive_bit();
unsigned char slave_ack();
void TX_byte(unsigned char TX_buffer);
unsigned char RX_byte(unsigned char ack_nack);
unsigned char PEC_cal(unsigned char pec[],int n);
unsigned long int MEM_READ( unsigned char slave_addR, unsigned char cmdR );
void Init_LCD();
void mlx90614_POW_0() { P1OUT &= ~0x08;} // define P6.3 ---> POW
void mlx90614_POW_1() { P1OUT |= 0x08;}
void mlx90614_GND_0() { P1OUT &= ~0x01;} // define P6.0 ---> GND
void mlx90614_GND_1() { P1OUT |= 0x01;}
void mlx90614_SCL_0() { P1OUT &= ~0x04;} // define P6.2 ---> SCL
void mlx90614_SCL_1() { P1OUT |= 0x04;}
void mlx90614_SDA_0() { P1OUT &= ~0x02;} // define P6.1 ---> SDA
void mlx90614_SDA_1() { P1OUT |= 0x02;}
#define _SDA_OUTPUT P1DIR |=0x02; //Set SDA as Output
#define _SDA_INPUT P1DIR &=~0x02; //Set SDA as Input
#define SDA ((P1IN & BIT1)>>1) //define input pin
//*************************************************************
//*************************************************************
void Delay(unsigned int n)
{
unsigned int i;
for(i=0;i<n;i++)
_NOP();
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: start_bit
//----------------------------------------------------------------------------------------------------------------------------------------//
void start_bit()
{
_SDA_OUTPUT; //Set SDA as output
mlx90614_SDA_1();
Delay(3);
mlx90614_SCL_1();
Delay(40);
mlx90614_SDA_0();
Delay(40);
mlx90614_SCL_0();
Delay(3);
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: stop_bit
//----------------------------------------------------------------------------------------------------------------------------------------//
void stop_bit()
{
_SDA_OUTPUT; //Set SDA as output
mlx90614_SCL_0();
Delay(40);
mlx90614_SDA_0();
Delay(40);
mlx90614_SCL_1();
Delay(40);
mlx90614_SDA_1();
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: send_bit
//----------------------------------------------------------------------------------------------------------------------------------------//
void send_bit(unsigned char bit_out)
{
_SDA_OUTPUT; //Set SDA as output
Delay(5);
if(bit_out==0) {mlx90614_SDA_0();}else{mlx90614_SDA_1();}
Delay(3);
mlx90614_SCL_1();
Delay(32);
mlx90614_SCL_0();
Delay(32);
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: receive_bit
//----------------------------------------------------------------------------------------------------------------------------------------//
unsigned char receive_bit()
{
unsigned char bit_in;
_SDA_INPUT; //Set SDA as input
mlx90614_SCL_1();
Delay(16);
if(SDA==1){bit_in=1;}else{bit_in=0;}
Delay(16);
mlx90614_SCL_0();
Delay(32);
return bit_in;
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: slave_ack
//1 - ACK
//0 -NACK
//----------------------------------------------------------------------------------------------------------------------------------------//
unsigned char slave_ack()
{
unsigned char ack;
ack=0;
_SDA_INPUT; //Set SDA as input
mlx90614_SCL_1();
Delay(16);
if(SDA==1){ack=0;}else{ack=1;}
Delay(16);
mlx90614_SCL_0();
Delay(32);
return ack;
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: TX_byte
//----------------------------------------------------------------------------------------------------------------------------------------//
void TX_byte(unsigned char TX_buffer)
{
unsigned char Bit_counter;
unsigned char bit_out;
for(Bit_counter=8;Bit_counter;Bit_counter--)
{
if(TX_buffer&0x80){bit_out=1;}else{bit_out=0;}
send_bit(bit_out); //Send the current bit on SMBus
TX_buffer<<=1; //Get next bit to check
}
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//Name: RX_byte
//Parameters: unsigned char ack_nack (acknowledgment bit)
//0 - Master device sends ACK
//1 - Master device sends NACK
//----------------------------------------------------------------------------------------------------------------------------------------//
unsigned char RX_byte(unsigned char ack_nack)
{
unsigned char RX_buffer;
unsigned char Bit_counter;
for(Bit_counter=8;Bit_counter;Bit_counter--)
{
if(receive_bit()==1) //Read a bit from the SDA line
{
RX_buffer<<=1; //If the bit is HIGH save 1 in RX_buffer
RX_buffer|=0x01;
}
else //If the bit is LOW save 0 in RX_buffer
{
RX_buffer<<=1;
RX_buffer&=0xfe;
}
}
send_bit(ack_nack); //Sends acknowledgment bit
return RX_buffer;
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//CALCULATE THE PEC PACKET
//----------------------------------------------------------------------------------------------------------------------------------------//
unsigned char PEC_cal(unsigned char pec[],int n)
{
unsigned char crc[6];
unsigned char Bitposition=47;
unsigned char shift;
unsigned char i;
unsigned char j;
unsigned char temp;
do{
crc[5]=0; //Load CRC value 0x000000000107
crc[4]=0;
crc[3]=0;
crc[2]=0;
crc[1]=0x01;
crc[0]=0x07;
Bitposition=47; //Set maximum bit position at 47
shift=0; //Find first 1 in the transmitted bytes
i=5; //Set highest index (package byte index)
j=0; //Byte bit index, from lowest
while((pec[i]&(0x80>>j))==0 && (i>0))
{
Bitposition--;
if(j<7){ j++;}
else {j=0x00;i--;}
}//the position of highest "1" bit in Bitposition is calculated
shift=Bitposition-8; //Get shift value for CRC value
while(shift)
{
for(i=5;i<0xFF;i--)
{
if((crc[i-1]&0x80) && (i>0)) //Check if the MSB of the byte lower is "1"
{ //Yes - current byte + 1
temp=1; //No - current byte + 0
} //So that "1" can shift between bytes
else { temp=0;}
crc[i]<<=1;
crc[i]+=temp;
}
shift--;
}
//Exclusive OR between pec and crc
for(i=0;i<=5;i++) { pec[i]^=crc[i]; }
}
while(Bitposition>8);
return pec[0];
}
//----------------------------------------------------------------------------------------------------------------------------------------//
//READ DATA FROM RAM/EEPROM
//----------------------------------------------------------------------------------------------------------------------------------------//
unsigned long int MEM_READ(unsigned char slave_addR, unsigned char cmdR)
{
unsigned char DataL; //
unsigned char DataH; //Data packets from MLX90614
unsigned char PEC; //
unsigned long int Data; //Register value returned from MLX90614
unsigned char Pecreg; //Calculated PEC byte storage
unsigned char arr[6]; //Buffer for the sent bytes
unsigned char ack_nack;
unsigned char SLA;
SLA=(slave_addR<<1);
begin:
start_bit(); //Send start bit
TX_byte(SLA); //Send slave address, write
if(slave_ack()==0){stop_bit();goto begin;} //Send command
TX_byte(cmdR);
if(slave_ack()==0){stop_bit();goto begin;}//Send Repeated start bit
start_bit(); //Send slave address, read
TX_byte(SLA+1);
if(slave_ack()==0){stop_bit();goto begin;}
DataL=RX_byte(0); //
//Read two bytes data
DataH=RX_byte(0); //
PEC=RX_byte(ack_nack); //Read PEC from MLX90614
if(ack_nack==1) //Master sends ack or nack
//This depends on the pec calculation,
//if the PEC is not correct, send nack and goto begin
{stop_bit();goto begin;} //Send stop bit
stop_bit();
arr[5]=(SLA);
arr[4]=cmdR;
arr[3]=(SLA+1);
arr[2]=DataL;
arr[1]=DataH;
arr[0]=0;
Pecreg=PEC_cal(arr,6); //Calculate CRC
if(PEC==Pecreg){ ack_nack=0;}
else{ ack_nack=1;}
Data=(DataH*256)+DataL;
return Data;
}
//---------------------------------------
//Name: CALTEMP
//Temperature data is T=(Data)*0.02-273.15
//---------------------------------------
float CalcTemp(unsigned int value )
{
float temp;
temp=(value*0.02)-273.15;
_NOP();
return temp;
}
//------------------------------------------------------------------------------
// LCD Test Code
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
// Init_LCD.
//------------------------------------------------------------------------------
//*************************************************************
//*************************************************************
/*LCD初始化：把控制引脚LCD_CS,LCD_SCL,LCD_SI,LCD_A0，LCD_RES,LCD_BLAEN等配置为输出*/
void Init_LCD()
{
P6DIR|=BIT7; //背光引脚设置为输出，打开背光灯
P8DIR|=(BIT5+BIT6+BIT7); //复位引脚LCD_RES设置为输出
P9DIR|=(BIT0+BIT1+BIT2+BIT3);//LCD控制引脚CS,SCL,SI,A0设置为输出
initLCDM(); //初始化LCDM
ClearRAM(0,0,128,8); //清屏
}
void main(void)
{
volatile unsigned int i;
char temp[16];
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P11DIR = BIT0 + BIT1 + BIT2; // ACLK ,MCLK ,MCLK 输出方向
P11SEL = BIT0 + BIT1 + BIT2;
P7SEL |= 0x03; // 设置DCO范围
UCSCTL1 = DCORSEL_4; // 选择FLL参考源自REFO
UCSCTL2 |= 0x79; // Set DCO Multiplier for 8MHz
UCSCTL4 = SELM_3 + SELA_0 + SELS_3; // 配置 MCLK = DCOC,SMCLK =DCOC,ACLK=XT1
UCSCTL6 |= SMCLKOFF;
while (SFRIFG1 & OFIFG) //清除OFIFG,and XT1OFFG ,DCOFFG
{
UCSCTL7 &= ~( XT1LFOFFG + DCOFFG);
SFRIFG1 &= ~OFIFG;
}
Init_LCD();
unsigned long int DATA;
_SDA_OUTPUT;
P1SEL |= BIT2;
mlx90614_SCL_0(); //
Delay(12000); //SMBus request，Switch PWM mode to SMBus mode(at least 2ms)
mlx90614_SCL_1(); //
while(1)
{
DATA=MEM_READ(0x5a,0x07);
temp[16]=CalcTemp(DATA);
sprintf(temp,"温度:%.2f度");
Display_String_Unregular(0,6,temp);
}
}