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器件型号：MSP430FR2433 工具与软件：
大家好！
我将通过 I2C 连接 MPU-6050加速计和 CCS811气体传感器。
使用逻辑分析仪、在 一段时间后、UCBBUSY 被置位、且一个开始位挂起。 执行两次时、它 在请求气体传感器的数据寄存器后挂起。
我想值得注意的是、SCL 线稍后会转换为高电平。
寄存器的写入/读取代码如下所示：
// Wake up the MPU-6050
slaveAddress = MPU_ADDR;
TX_Data[1] = PWR_MGMT_1;
TX_Data[0] = 0x08; // Set 8 MHz clock; disable temperature sensor
TX_ByteCtr = 2;
i2c_wr(slaveAddress);
__delay_cycles(50000); // According to datasheet, hold ~30 ms
// Because of gyroscope based clock oscillator
slaveAddress = CCS811_ADDR; // Make transition from boot to application mode
TX_Data[0] = CCS811_APP_START;
TX_ByteCtr = 1;
i2c_wr(slaveAddress);
__delay_cycles(30000);
slaveAddress = CCS811_ADDR;
TX_Data[1] = CCS811_MEAS_MODE;
TX_Data[0] = 0x10; // Put CCS to normal mode, no interrupt enable
TX_ByteCtr = 2;
i2c_wr(slaveAddress);
__delay_cycles(15000);
while(1)
{
// Register pointing
slaveAddress = MPU_ADDR;
TX_Data[0] = ACCEL_XOUT_H; // First address of the set
TX_ByteCtr = 1;
i2c_wr(slaveAddress);
// Read six bytes of data
slaveAddress = MPU_ADDR;
RX_ByteCtr = 6;
i2c_rd(slaveAddress);
xAccel = RX_Data[5] << 8 | RX_Data[4];
yAccel = RX_Data[3] << 8 | RX_Data[2];
zAccel = RX_Data[1] << 8 | RX_Data[0];
//--------------------------------------------------------------------------------//
__delay_cycles(50000);
//--------------------------------------------------------------------------------//
slaveAddress = CCS811_ADDR;
TX_Data[0] = CCS811_ALG_RESULT_DATA;
TX_ByteCtr = 1;
i2c_wr(slaveAddress);
// Reading operation of environment data register
slaveAddress = CCS811_ADDR;
RX_ByteCtr = 8;
i2c_rd(slaveAddress);
co2Lvl = (RX_Data[0] << 8 | RX_Data[1]);
tvocLvl = (RX_Data[2] << 8 | RX_Data[3]);
__delay_cycles(100000);
} //End while
寄存器 地址可从相应的器件数据表中提取。
作为参考、I2C 相关代码如下所示：
/**
* Configuration of I2C module
*/
void i2c_conf(void)
{
// I2C pins configuration
P1SEL0 |= BIT2 | BIT3;
// Disable the GPIO power-on default high-impedance mode to activate
// previously configured port settings
PM5CTL0 &= ~LOCKLPM5;
// Configure USCI_B0 for I2C mode
UCB0CTL1 |= UCSWRST; // Software reset enabled
UCB0CTLW0 |= UCMODE_3 | UCMST; // I2C mode, Master mode, SMCLK
UCB0CTLW0 |= UCSSEL__SMCLK | UCSYNC; // Use SMCLK as clock source, sync
UCB0CTLW1 |= UCASTP_2; // Automatic stop generated by
// reaching data acquisition boundary
UCB0BR0 = 0x0008; // baudrate = SMCLK / 8 = ~100 kHz
UCB0CTL1 &= ~UCSWRST; // Disable SW reset
}
/**
* Write function
*/
void i2c_wr(unsigned char addr)
{
while(UCB0CTL1 & UCTXSTP); // Ensure stop condition sent
UCB0CTL1 |= UCSWRST;
UCB0I2CSA = addr; // Slave address
UCB0TBCNT = TX_ByteCtr;
UCB0CTL1 &= ~UCSWRST;
UCB0IE |= UCTXIE | UCRXIE | UCBCNTIE; // Enable Tx, RX and
// byte count interruptions
UCB0CTL1 |= UCTR; // Transmitter mode
UCB0CTL1 |= UCTXSTT; // and send START condition
__bis_SR_register(LPM0_bits|GIE); // Enter LPM0 w/ interrupt
}
/**
* Read function
*/
void i2c_rd(unsigned char addr)
{
while(UCB0CTL1 & UCTXSTP); // Ensure stop condition sent
UCB0CTL1 |= UCSWRST;
UCB0I2CSA = addr; // Slave address
UCB0TBCNT = RX_ByteCtr;
UCB0CTL1 &= ~UCSWRST;
UCB0IE |= UCTXIE | UCRXIE | UCBCNTIE; // Enable Tx and RX interruptions
UCB0CTL1 &= ~UCTR; // Receiver mode
UCB0CTL1 |= UCTXSTT; // and send START condition
__bis_SR_register(LPM0_bits|GIE); // Enter LPM0 w/ interrupt
}
/**
* UCB0 ISR
*/
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCI_B0_VECTOR
__interrupt void USCIB0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_B0_VECTOR))) USCIB0_ISR (void)
#else
#error Compiler not supported!
#endif
{
switch(__even_in_range(UCB0IV, USCI_I2C_UCBIT9IFG))
{
case USCI_I2C_UCRXIFG0:
if (RX_ByteCtr--)
{
RX_Data[RX_ByteCtr] = UCB0RXBUF; // Get received byte
}
break;
case USCI_I2C_UCTXIFG0:
if (TX_ByteCtr--) // TRUE if more bytes remain
{
UCB0TXBUF = TX_Data[TX_ByteCtr]; // Load TX buffer
}
break;
case USCI_I2C_UCBCNTIFG:
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
break;
}
}
感谢任何帮助。
