使用 MSP430FR5969 MCU 从 TMP117 传感器读取温度值

Reading temperature values from TMP117 sensor using MSP430FR5969 MCU

我正在尝试通过 I2C 协议从 TMP117 传感器 [1] connected to an MSP430FR5969 MCU [2] 读取温度值。传感器结果寄存器中的数据为二进制补码格式,数据宽度为16位,分辨率为0.0078125℃。我使用 Code Composer Studio 对 MCU 进行编程,并附上了以下代码:

#include <msp430.h> 
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>

#define SLAVE_ADDR  0x48
#define CONVERSION_READY  0x10
#define TMP117_TEMP_REG  0x00
#define TMP117_CONFIG_REG  0x01
#define TMP117_RESOLUTION 0.0078125f

#define CMD_TYPE_0_SLAVE      0
#define CMD_TYPE_1_SLAVE      1
#define CMD_TYPE_2_SLAVE      2

#define CMD_TYPE_0_MASTER      3
#define CMD_TYPE_1_MASTER      4
#define CMD_TYPE_2_MASTER      5

#define TYPE_0_LENGTH   1
#define TYPE_1_LENGTH   2
#define TYPE_2_LENGTH   6

#define MAX_BUFFER_SIZE     20

char temperature[] = "Temperature is: ";
char dot[] = ".";
char celcuis[] = " degree Celcius\r\n";

int i;
char text[] = " I am an MSP430FR5969\r\n";

char rx_char[5];

volatile int rx_val = 0;

void clockSetup();
void gpioSetup();
void uartSetup();
void i2cSetup();
void ser_output(char *str);

uint8_t MasterType1 [TYPE_1_LENGTH] = {0x02, 0x20};

uint8_t SlaveType1 [TYPE_1_LENGTH] = {0};

typedef enum I2C_ModeEnum{
    IDLE_MODE,
    NACK_MODE,
    TX_REG_ADDRESS_MODE,
    RX_REG_ADDRESS_MODE,
    TX_DATA_MODE,
    RX_DATA_MODE,
    SWITCH_TO_RX_MODE,
    SWITHC_TO_TX_MODE,
    TIMEOUT_MODE
} I2C_Mode;

I2C_Mode MasterMode = IDLE_MODE;

/* The Register Address/Command to use*/
uint8_t TransmitRegAddr = 0;

uint8_t ReceiveBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t RXByteCtr = 0;
uint8_t ReceiveIndex = 0;
uint8_t TransmitBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t TXByteCtr = 0;
uint8_t TransmitIndex = 0;

I2C_Mode I2C_Master_WriteReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data, uint8_t count);

I2C_Mode I2C_Master_ReadReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t count);
void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count);

I2C_Mode I2C_Master_ReadReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t count)
{
    MasterMode = TX_REG_ADDRESS_MODE;
    TransmitRegAddr = reg_addr;
    RXByteCtr = count;
    TXByteCtr = 0;
    ReceiveIndex = 0;
    TransmitIndex = 0;

    UCB0I2CSA = dev_addr;
    UCB0IFG &= ~(UCTXIFG + UCRXIFG);
    UCB0IE &= ~UCRXIE;
    UCB0IE |= UCTXIE;

    UCB0CTLW0 |= UCTR + UCTXSTT;
    __bis_SR_register(LPM0_bits + GIE);

    return MasterMode;
}

I2C_Mode I2C_Master_WriteReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data, uint8_t count)
{
    MasterMode = TX_REG_ADDRESS_MODE;
    TransmitRegAddr = reg_addr;

    CopyArray(reg_data, TransmitBuffer, count);

    TXByteCtr = count;
    RXByteCtr = 0;
    ReceiveIndex = 0;
    TransmitIndex = 0;

    UCB0I2CSA = dev_addr;
    UCB0IFG &= ~(UCTXIFG + UCRXIFG);
    UCB0IE &= ~UCRXIE;
    UCB0IE |= UCTXIE;

    UCB0CTLW0 |= UCTR + UCTXSTT;
  __bis_SR_register(LPM0_bits + GIE);

    return MasterMode;
}

void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count)
{
    uint8_t copyIndex = 0;
    for (copyIndex = 0; copyIndex < count; copyIndex++)
    {
        dest[copyIndex] = source[copyIndex];
    }
}

void main(void)
{
    WDTCTL = WDTPW | WDTHOLD;

    clockSetup();
    gpioSetup();
    uartSetup();
    i2cSetup();

    __bis_SR_register(GIE);


    while (1)
    {
           _delay_cycles(500000);
            I2C_Master_ReadReg(SLAVE_ADDR, 0x00, TYPE_1_LENGTH);
            CopyArray(ReceiveBuffer, SlaveType1, TYPE_1_LENGTH);

            if(ReceiveBuffer[1] & CONVERSION_READY)
            {
                I2C_Master_ReadReg(SLAVE_ADDR, 0x00, TYPE_1_LENGTH);
                CopyArray(ReceiveBuffer, SlaveType1, TYPE_1_LENGTH);
                _no_operation();
            }

    ltoa(rx_val, rx_char, 10);
    ser_output(temperature);
    ser_output(rx_char);
    ser_output(dot);
    ser_output(celcuis);
    }
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCI_B0_VECTOR
__interrupt void USCI_B0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_B0_VECTOR))) USCI_B0_ISR (void)
#else
#error Compiler not supported!
#endif
{
  //Must read from UCB0RXBUF
 //// uint8_t rx_val = 0;
  switch(__even_in_range(UCB0IV, USCI_I2C_UCBIT9IFG))
  {
    case USCI_NONE:          break;         // Vector 0: No interrupts
    case USCI_I2C_UCALIFG:   break;         // Vector 2: ALIFG
    case USCI_I2C_UCNACKIFG:                // Vector 4: NACKIFG
      break;
    case USCI_I2C_UCSTTIFG:  break;         // Vector 6: STTIFG
    case USCI_I2C_UCSTPIFG:  break;         // Vector 8: STPIFG
    case USCI_I2C_UCRXIFG3:  break;         // Vector 10: RXIFG3
    case USCI_I2C_UCTXIFG3:  break;         // Vector 12: TXIFG3
    case USCI_I2C_UCRXIFG2:  break;         // Vector 14: RXIFG2
    case USCI_I2C_UCTXIFG2:  break;         // Vector 16: TXIFG2
    case USCI_I2C_UCRXIFG1:  break;         // Vector 18: RXIFG1
    case USCI_I2C_UCTXIFG1:  break;         // Vector 20: TXIFG1
    case USCI_I2C_UCRXIFG0:                 // Vector 22: RXIFG0
        rx_val = UCB0RXBUF;
        if (RXByteCtr)
        {
          ReceiveBuffer[ReceiveIndex++] = rx_val;
          RXByteCtr--;
        }
        if (RXByteCtr == 1)
        {
          UCB0CTLW0 |= UCTXSTP;
        }
        else if (RXByteCtr == 0)
        {
          UCB0IE &= ~UCRXIE;
          MasterMode = IDLE_MODE;
          __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
        }
        break;
    case USCI_I2C_UCTXIFG0:                 // Vector 24: TXIFG0
        switch (MasterMode)
        {
          case TX_REG_ADDRESS_MODE:
              UCB0TXBUF = TransmitRegAddr;
              if (RXByteCtr)
                  MasterMode = SWITCH_TO_RX_MODE;   // Need to start receiving now
              else
                  MasterMode = TX_DATA_MODE;        // Continue to transmision with the data in Transmit Buffer
              break;

          case SWITCH_TO_RX_MODE:
              UCB0IE |= UCRXIE;              // Enable RX interrupt
              UCB0IE &= ~UCTXIE;             // Disable TX interrupt
              UCB0CTLW0 &= ~UCTR;            // Switch to receiver
              MasterMode = RX_DATA_MODE;    // State state is to receive data
              UCB0CTLW0 |= UCTXSTT;          // Send repeated start
              if (RXByteCtr == 1)
              {
                  //Must send stop since this is the N-1 byte
                  while((UCB0CTLW0 & UCTXSTT));
                  UCB0CTLW0 |= UCTXSTP;      // Send stop condition
              }
              break;

          case TX_DATA_MODE:
              if (TXByteCtr)
              {
                  UCB0TXBUF = TransmitBuffer[TransmitIndex++];
                  TXByteCtr--;
              }
              else
              {
                  //Done with transmission
                  UCB0CTLW0 |= UCTXSTP;     // Send stop condition
                  MasterMode = IDLE_MODE;
                  UCB0IE &= ~UCTXIE;                       // disable TX interrupt
                  __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
              }
              break;

          default:
              __no_operation();
              break;
        }
        break;
    default: break;
  }
}

    void ser_output(char *str)
    {
        while(*str !=0)
        {
            while(!(UCA0IFG&UCTXIFG));
            UCA0TXBUF = *str++;
        }
    }

    void gpioSetup()
    {
         P1OUT   &= ~BIT0;                             // Clear P1.0 output latch
         P1DIR   |= BIT0;                              // For LED
         P1SEL1  |= BIT6 | BIT7;                      // I2C pins
         P2SEL1  |= BIT0 | BIT1;                      // USCI_A0 UART operation
         P2SEL0  &= ~(BIT0 | BIT1);
         PM5CTL0 &= ~LOCKLPM5;
    }

    void clockSetup()
    {
        FRCTL0 = FRCTLPW | NWAITS_1;
        CSCTL0_H = CSKEY >> 8;
        CSCTL1 = DCORSEL | DCOFSEL_0;
        CSCTL2 = SELA__VLOCLK | SELS__DCOCLK | SELM__DCOCLK;
        CSCTL3 = DIVA__1 | DIVS__1 | DIVM__1;
        CSCTL0_H = 0;
    }

    void uartSetup()
    {
        UCA0CTL1 |= UCSWRST;
        UCA0CTL1 |= UCSSEL_2;
        UCA0BR0 = 6;
        UCA0BR1 = 0;
        UCA0MCTLW = 0xAA;
        UCA0MCTLW |= UCOS16 | UCBRF_1;
        UCA0CTL1 &= ~UCSWRST;
        UCA0IE |= UCRXIE;
    }

    void i2cSetup()
    {
        UCB0CTLW0  |= UCSWRST;
        UCB0CTLW0 |= UCMODE_3 | UCMST | UCSSEL__SMCLK | UCSYNC;
        UCB0CTLW1  |= UCSSEL_2;
        UCB0BRW   = 10;
        UCB0I2CSA = 0x0048;
        UCB0CTLW0  &= ~UCSWRST;
        UCB0IE |= UCRXIE | UCNACKIE | UCBCNTIE;
    }

我得到以下数据:

Temperature values in ReceviedBuffer, and transmitted value to PuTTY terminal

(i) 我的第一个问题是为什么我在终端上得到 RecevieBuffer1 值和 RecevieBuffer[0].

的缺失值

(ii) 我的第二个问题是如何将 16 位原始数据转换为摄氏度值。

非常感谢

要从您的字节缓冲区中获取 16 位值,您需要将每个字节转换为 16 位值,将第二个字节移动 8 位,然后将两者相加。在一行中它看起来像这样:

int16_t value = int16_t(buffer[0]) | int16_t(buffer[1]) << 8;

根据您读取的 0x0aaf 值,我猜您使用的温度传感器可能会输出以摄氏度*100 为单位的值,以使其保持整数并仍然具有 100 度精度。因此,要获得以摄氏度为单位的值,您必须转换为浮点数或双精度数并除以 100.0。所以0x0aaf是2735,意思是27.35摄氏度。