BQ76920 I2C通信无法正确读取

各位大神救我！

我的控制器是TM4C123G开发板，按照bq76920说明书上的事例电路图，做了一个电路，但是控制器从bq76920上读取寄存器信息的时候，获得的结果永远都是255,（也就是说SDA一直是高电位？），在CCS里调试的时候，运行写指令的时候就会提示：

CORTEX_M4_0: Error: Debug Port error occurred.
CORTEX_M4_0: Trouble Halting Target CPU

这是为什么呢？我是完全按照事例电路连接的，（事例电路上没有上拉电阻，我在自己的电路里给SCL端和SDL端又加了上拉电阻以及3.3v的电压）。如何判断到底是电路出问题还是我的代码有问题呢？ 还有I2C通信的时候，一定要有CRC吗？ 如果我不需要充电放电保护，我可不可以直接把DSG和CHG都接地或者啥都不接？

这个是我的初始化程序，以及读和写的代码。真是不知道问题在哪里了T_T

//initialize I2C module 0
//Slightly modified version of TI's example code
void InitI2C0(void)
{
//enable I2C module 0
SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);

//reset module
SysCtlPeripheralReset(SYSCTL_PERIPH_I2C0);

//enable GPIO peripheral that contains I2C 0
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);

// Configure the pin muxing for I2C0 functions on port B2 and B3.
GPIOPinConfigure(GPIO_PB2_I2C0SCL);
GPIOPinConfigure(GPIO_PB3_I2C0SDA);

// Select the I2C function for these pins.
GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);

// Enable and initialize the I2C0 master module. Use the system clock for
// the I2C0 module. The last parameter sets the I2C data transfer rate.
// If false the data rate is set to 100kbps and if true the data rate will
// be set to 400kbps.
I2CMasterInitExpClk(I2C0_BASE, SysCtlClockGet(), false);

//clear I2C FIFOs
HWREG(I2C0_BASE + I2C_O_FIFOCTL) = 80008000;

UARTprintf("InitI2C0 \n");
}

////////////////////////////////////////////////////////////////////////////////////////

//read specified register on slave device
uint32_t I2CReceive(uint32_t slave_addr, uint8_t reg)
{
//specify that we are writing (a register address) to the
//slave device
I2CMasterSlaveAddrSet(I2C0_BASE, slave_addr, false);

//specify register to be read
I2CMasterDataPut(I2C0_BASE, reg);

//send control byte and register address byte to slave device
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);

//wait for MCU to finish transaction
while(I2CMasterBusy(I2C0_BASE));

//specify that we are going to read from slave device
I2CMasterSlaveAddrSet(I2C0_BASE, slave_addr, true);

//send control byte and read from the register we
//specified
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);

//wait for MCU to finish transaction
while(I2CMasterBusy(I2C0_BASE));

//return data pulled from the specified register
return I2CMasterDataGet(I2C0_BASE);
}

///////////////////////////////////////////////////////////////////////////////////////////

//sends an I2C command to the specified slave
void I2CSend(uint8_t slave_addr, uint8_t num_of_args, …)
{
// Tell the master module what address it will place on the bus when
// communicating with the slave.
I2CMasterSlaveAddrSet(I2C0_BASE, slave_addr, false);

//stores list of variable number of arguments
va_list vargs;

//specifies the va_list to "open" and the last fixed argument
//so vargs knows where to start looking
va_start(vargs, num_of_args);

//put data to be sent into FIFO
I2CMasterDataPut(I2C0_BASE, va_arg(vargs, uint8_t));

//if there is only one argument, we only need to use the
//single send I2C function
if(num_of_args == 1)
{
//Initiate send of data from the MCU
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);

// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));

//"close" variable argument list
va_end(vargs);
}

//otherwise, we start transmission of multiple bytes on the
//I2C bus
else
{
//Initiate send of data from the MCU
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);

// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));

//send num_of_args-2 pieces of data, using the
//BURST_SEND_CONT command of the I2C module

int i =1;
for( i = 1; i < (num_of_args – 1); i++)
{
//put next piece of data into I2C FIFO
I2CMasterDataPut(I2C0_BASE, va_arg(vargs, uint8_t));
//send next data that was just placed into FIFO
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);

// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));
}

//put last piece of data into I2C FIFO
I2CMasterDataPut(I2C0_BASE, va_arg(vargs, uint8_t));
//send next data that was just placed into FIFO
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
// Wait until MCU is done transferring.
while(I2CMasterBusy(I2C0_BASE));

//"close" variable args list
va_end(vargs);
}
}

万望各位前辈斧正

拜谢

Star Xu：

建议你用EV2300连接上机位软件先确认是不是能正常通讯。

Detian Shang：

回复 Star Xu:

除了用EV2300就没有别的办法了吗？ 我这里没有EV2300。。。

可不可能是通信代码有问题，导致无法通信呢？我用GPIOA PA0和PA1 和电脑通信，不会干扰控制器和bq76920通信吧？

user5170101：

回复 Detian Shang:

请问CRC是必须的？

Star Xu：

回复 user5170101:

如果您买的是CRC版的芯片，CRC是必须的。

user5170101：

回复 Star Xu:

我所使用的是BQ7694003DBTR，在手册上写的是CRC yes，但在通讯系统那章提到crc为optional，也就是非强制性。所以有此疑惑？