TI

数字传感器测温

2019-07-25 15:41发布

站内问答 / TI MCU
3024 11 1731
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！

  2. //*****************************************************************************
  3. //   MSP430x42x0 Demo - SD16_A, LCD
  4. //*****************************************************************************

  6. //MLX90614 Pin Config

  8. //GND-----6.0.....I/O supply the MLX90614
  9. //SDA-----6.1
  10. //SCL-----6.2
  11. //POW-----6.3.....I/O supply the MLX90614

  13. #include  <msp430x54x.h>
  14. #include <string.h>
  15. #include "lcdoperate.h"
  16. #include <math.h>

  18. unsigned int A1,A2,A3,A4,A5;


  21. //*************************************************************
  22. //*************************************************************
  23. #define uchar unsigned char
  24. #define uint  unsigned int
  25. void Delay(unsigned int n);
  26. void start_bit();
  27. void stop_bit();
  28. void send_bit(unsigned char bit_out);
  29. unsigned char receive_bit();
  30. unsigned char slave_ack();
  31. void TX_byte(unsigned char TX_buffer);
  32. unsigned char RX_byte(unsigned char ack_nack);
  33. unsigned char PEC_cal(unsigned char pec[],int n);
  34. unsigned long int MEM_READ( unsigned char slave_addR, unsigned char cmdR );                                                
  35. void  Init_LCD();
  36. void mlx90614_POW_0() { P1OUT &= ~0x08;}  // define P6.3 ---> POW
  37. void mlx90614_POW_1() { P1OUT |= 0x08;}

  39. void mlx90614_GND_0() { P1OUT &= ~0x01;}  // define P6.0 ---> GND
  40. void mlx90614_GND_1() { P1OUT |= 0x01;}

  42. void mlx90614_SCL_0() { P1OUT &= ~0x04;}  // define P6.2 ---> SCL
  43. void mlx90614_SCL_1() { P1OUT |= 0x04;}

  45. void mlx90614_SDA_0() { P1OUT &= ~0x02;}  // define P6.1 ---> SDA
  46. void mlx90614_SDA_1() { P1OUT |= 0x02;}


  49. #define _SDA_OUTPUT P1DIR |=0x02; //Set SDA as Output
  50. #define _SDA_INPUT P1DIR &=~0x02; //Set SDA as Input

  52. #define SDA ((P1IN & BIT1)>>1) //define input pin

  54. //*************************************************************
  55. //*************************************************************

  57. void Delay(unsigned int n)
  58. {
  59.   unsigned int i;
  60.   for(i=0;i<n;i++)
  61.   _NOP();
  62. }

  64. //----------------------------------------------------------------------------------------------------------------------------------------//
  65. //Name: start_bit
  66. //----------------------------------------------------------------------------------------------------------------------------------------//
  67. void start_bit()
  68. {
  69.   _SDA_OUTPUT; //Set SDA as output
  70.   mlx90614_SDA_1();
  71.   Delay(3);
  72.   mlx90614_SCL_1();
  73.   
  74.   Delay(40);
  75.   mlx90614_SDA_0();
  76.   Delay(40);
  77.   mlx90614_SCL_0();
  78.   Delay(3);
  79.   
  80. }

  82. //----------------------------------------------------------------------------------------------------------------------------------------//
  83. //Name: stop_bit
  84. //----------------------------------------------------------------------------------------------------------------------------------------//
  85. void stop_bit()
  86. {
  87.   _SDA_OUTPUT; //Set SDA as output

  89.   mlx90614_SCL_0();
  90.     Delay(40);
  91.   mlx90614_SDA_0();
  92.   Delay(40);
  93.   mlx90614_SCL_1();
  94.   Delay(40);
  95.   mlx90614_SDA_1();
  96. }

  98. //----------------------------------------------------------------------------------------------------------------------------------------//
  99. //Name: send_bit
  100. //----------------------------------------------------------------------------------------------------------------------------------------//
  101. void send_bit(unsigned char bit_out)
  102. {
  103.   _SDA_OUTPUT; //Set SDA as output
  104.   Delay(5);
  105.   if(bit_out==0) {mlx90614_SDA_0();}else{mlx90614_SDA_1();}
  106.   Delay(3);
  107.   mlx90614_SCL_1();
  108.   Delay(32);
  109.   mlx90614_SCL_0();
  110.   Delay(32);
  111. }

  113. //----------------------------------------------------------------------------------------------------------------------------------------//
  114. //Name: receive_bit
  115. //----------------------------------------------------------------------------------------------------------------------------------------//
  116. unsigned char receive_bit()
  117. {
  118.   unsigned char bit_in;
  119.   _SDA_INPUT; //Set SDA as input
  120.   mlx90614_SCL_1();
  121.   Delay(16);
  122.   if(SDA==1){bit_in=1;}else{bit_in=0;}
  123.   Delay(16);
  124.   mlx90614_SCL_0();
  125.   Delay(32);
  126.   return bit_in;
  127. }

  129. //----------------------------------------------------------------------------------------------------------------------------------------//
  130. //Name: slave_ack
  131. //1 - ACK
  132. //0 -NACK
  133. //----------------------------------------------------------------------------------------------------------------------------------------//
  134. unsigned char slave_ack()
  135. {
  136.   unsigned char ack;
  137.   ack=0;
  138.   _SDA_INPUT; //Set SDA as input
  139.   mlx90614_SCL_1();
  140.   Delay(16);
  141.   if(SDA==1){ack=0;}else{ack=1;}
  142.   Delay(16);
  143.   mlx90614_SCL_0();
  144.   Delay(32);
  145.   return ack;
  146. }

  148. //----------------------------------------------------------------------------------------------------------------------------------------//
  149. //Name: TX_byte
  150. //----------------------------------------------------------------------------------------------------------------------------------------//
  151. void TX_byte(unsigned char TX_buffer)
  152. {
  153.   unsigned char Bit_counter;
  154.   unsigned char bit_out;
  155.   for(Bit_counter=8;Bit_counter;Bit_counter--)
  156.   {
  157.     if(TX_buffer&0x80){bit_out=1;}else{bit_out=0;}
  158.     send_bit(bit_out); //Send the current bit on SMBus
  159.     TX_buffer<<=1; //Get next bit to check
  160.   }
  161. }

  163. //----------------------------------------------------------------------------------------------------------------------------------------//
  164. //Name: RX_byte
  165. //Parameters: unsigned char ack_nack (acknowledgment bit)
  166. //0 - Master device sends ACK
  167. //1 - Master device sends NACK
  168. //----------------------------------------------------------------------------------------------------------------------------------------//
  169. unsigned char RX_byte(unsigned char ack_nack)
  170. {
  171.         unsigned char RX_buffer;
  172.         unsigned char Bit_counter;
  173.         for(Bit_counter=8;Bit_counter;Bit_counter--)
  174.         {
  175.          if(receive_bit()==1) //Read a bit from the SDA line
  176.           {
  177.            RX_buffer<<=1; //If the bit is HIGH save 1 in RX_buffer
  178.            RX_buffer|=0x01;
  179.           }
  180.          else //If the bit is LOW save 0 in RX_buffer
  181.           {
  182.            RX_buffer<<=1;
  183.            RX_buffer&=0xfe;
  184.           }
  185.         }
  186.         send_bit(ack_nack); //Sends acknowledgment bit
  187.         return RX_buffer;
  188. }


  191. //----------------------------------------------------------------------------------------------------------------------------------------//
  192. //CALCULATE THE PEC PACKET
  193. //----------------------------------------------------------------------------------------------------------------------------------------//
  194. unsigned char PEC_cal(unsigned char pec[],int n)
  195. {
  196.     unsigned char crc[6];
  197.     unsigned char Bitposition=47;
  198.     unsigned char shift;
  199.     unsigned char i;
  200.     unsigned char j;
  201.     unsigned char temp;
  202.   do{
  203.     crc[5]=0; //Load CRC value 0x000000000107
  204.     crc[4]=0;
  205.     crc[3]=0;
  206.     crc[2]=0;
  207.     crc[1]=0x01;
  208.     crc[0]=0x07;
  209.     Bitposition=47; //Set maximum bit position at 47
  210.     shift=0;        //Find first 1 in the transmitted bytes
  211.     i=5; //Set highest index (package byte index)
  212.     j=0; //Byte bit index, from lowest
  213.     while((pec[i]&(0x80>>j))==0 && (i>0))
  214.     {
  215.      Bitposition--;
  216.      if(j<7){ j++;}
  217.      else {j=0x00;i--;}
  218.     }//the position of highest "1" bit in Bitposition is calculated
  219.     shift=Bitposition-8; //Get shift value for CRC value
  220.         
  221.     while(shift)
  222.     {
  223.       for(i=5;i<0xFF;i--)
  224.       {
  225.        if((crc[i-1]&0x80) && (i>0)) //Check if the MSB of the byte lower is "1"
  226.         { //Yes - current byte + 1
  227.          temp=1; //No - current byte + 0
  228.         } //So that "1" can shift between bytes
  229.        else { temp=0;}
  230.       crc[i]<<=1;
  231.       crc[i]+=temp;
  232.       }
  233.     shift--;
  234.     }
  235.     //Exclusive OR between pec and crc
  236.     for(i=0;i<=5;i++) { pec[i]^=crc[i]; }
  237.     }
  238.     while(Bitposition>8);
  239.     return pec[0];
  240.     }
  241.         
  242. //----------------------------------------------------------------------------------------------------------------------------------------//
  243. //READ DATA FROM RAM/EEPROM
  244. //----------------------------------------------------------------------------------------------------------------------------------------//
  245. unsigned long int MEM_READ(unsigned char slave_addR, unsigned char cmdR)
  246. {
  247.   unsigned char DataL; //
  248.   unsigned char DataH; //Data packets from MLX90614
  249.   unsigned char PEC; //
  250.   unsigned long int Data; //Register value returned from MLX90614
  251.   unsigned char Pecreg; //Calculated PEC byte storage
  252.   unsigned char arr[6]; //Buffer for the sent bytes
  253.   unsigned char ack_nack;
  254.   unsigned char SLA;
  255.   SLA=(slave_addR<<1);
  256. begin:
  257.   start_bit(); //Send start bit
  258.   TX_byte(SLA); //Send slave address, write
  259.   if(slave_ack()==0){stop_bit();goto begin;} //Send command
  260.   TX_byte(cmdR);
  261.   if(slave_ack()==0){stop_bit();goto begin;}//Send Repeated start bit
  262.   start_bit(); //Send slave address, read
  263.   TX_byte(SLA+1);
  264.   if(slave_ack()==0){stop_bit();goto begin;}
  265.   DataL=RX_byte(0); //
  266.   //Read two bytes data
  267.   DataH=RX_byte(0); //
  268.   PEC=RX_byte(ack_nack); //Read PEC from MLX90614
  269.   if(ack_nack==1) //Master sends ack or nack
  270.   //This depends on the pec calculation,
  271.   //if the PEC is not correct, send nack and goto begin
  272.   {stop_bit();goto begin;} //Send stop bit
  273.   stop_bit();
  274.   arr[5]=(SLA);
  275.   arr[4]=cmdR;
  276.   arr[3]=(SLA+1);
  277.   arr[2]=DataL;
  278.   arr[1]=DataH;
  279.   arr[0]=0;
  280.   Pecreg=PEC_cal(arr,6); //Calculate CRC
  281.   if(PEC==Pecreg){ ack_nack=0;}
  282.   else{ ack_nack=1;}
  283.   Data=(DataH*256)+DataL;
  284.   return Data;
  285. }

  287. //---------------------------------------
  288. //Name: CALTEMP           
  289. //Temperature data is T=(Data)*0.02-273.15
  290. //---------------------------------------
  291. float CalcTemp(unsigned int value )
  292. {
  293.         float temp;
  294.         
  295.         temp=(value*0.02)-273.15;
  296.         _NOP();
  297.         
  298.         return temp;
  299. }
  300. //------------------------------------------------------------------------------
  301. // LCD Test Code
  302. //------------------------------------------------------------------------------

  304. //------------------------------------------------------------------------------
  305. // Init_LCD.
  306. //------------------------------------------------------------------------------

  308. //*************************************************************
  309. //*************************************************************
  310. /*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*/
  311. void  Init_LCD()
  312. {
  313.   P6DIR|=BIT7;          //背光引脚设置为输出，打开背光灯
  314.   P8DIR|=(BIT5+BIT6+BIT7);  //复位引脚LCD_RES设置为输出
  315.   P9DIR|=(BIT0+BIT1+BIT2+BIT3);//LCD控制引脚CS,SCL,SI,A0设置为输出
  316.   initLCDM();                  //初始化LCDM
  317.   ClearRAM(0,0,128,8);         //清屏
  318. }
  319. void main(void)
  320. {
  321.   volatile unsigned int i;   
  322.   char temp[16];
  323.   WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  324.   
  325.   P11DIR = BIT0 + BIT1 + BIT2;                    // ACLK ,MCLK ,MCLK  输出方向
  326.       P11SEL = BIT0 + BIT1 + BIT2;
  327.        P7SEL |= 0x03;                                   // 设置DCO范围  
  328.      UCSCTL1 = DCORSEL_4;                             // 选择FLL参考源自REFO  
  329.      UCSCTL2 |= 0x79;                                 // Set DCO Multiplier for 8MHz
  330.      UCSCTL4 = SELM_3 + SELA_0 + SELS_3;              // 配置 MCLK = DCOC,SMCLK =DCOC,ACLK=XT1
  331.      UCSCTL6 |= SMCLKOFF;
  332.      while (SFRIFG1 & OFIFG)                          //清除OFIFG,and  XT1OFFG ,DCOFFG
  333.      {
  334.           UCSCTL7 &= ~(  XT1LFOFFG + DCOFFG);
  335.           SFRIFG1 &= ~OFIFG;
  336.      }        
  337.   Init_LCD();

  339.     unsigned long int DATA;
  340.          
  341.     _SDA_OUTPUT;
  342.      P1SEL |= BIT2;
  343.      
  344.       mlx90614_SCL_0();                                //
  345.        Delay(12000);                                //SMBus request，Switch PWM mode to SMBus mode(at least 2ms)
  346.       mlx90614_SCL_1();                //
  347.   while(1)
  348.        {
  349.       DATA=MEM_READ(0x5a,0x07);
  350.    
  351.         temp[16]=CalcTemp(DATA);
  352.    sprintf(temp,"温度:%.2f度");
  353.     Display_String_Unregular(0,6,temp);
  354.    
  355.        }
  356. }



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11条回答
lefeng
2019-07-26 11:21
看看时序图怎么说的，其实就是先打开谁，然后谁才能工作等等

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