程序如下，是照着TivaWare的example改的，请帮我看看有什么问题
我想用示波器观察SCL（PB2）的波形，可是在我接上示波器并按RESET键，从示波器里看不到任何波形，是不是没有配置好？同时我在CCS5.4的debug中单步运行，想查看寄存器，可是所有寄存器均显示unable to read 请问这是什么情况？ 如何能判断我的I2C配置成功并且可以发送数据了呢 ？？
#include <stdint.h>
#include <stdbool.h>
#include "inc/tm4c123gh6pm.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/sysctl.h"
#include "driverlib/interrupt.h"
#include "driverlib/gpio.h"
#include "driverlib/timer.h"
#include "driverlib/i2c.h"
#include "driverlib/udma.h"
#include "driverlib/adc.h"
int main(void)
{
SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);// sysclock is 40Mhz
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
GPIOPinTypeI2C(GPIO_PORTB_BASE,GPIO_PIN_2|GPIO_PIN_3);//Configure the I2C pins
//add2lines
SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);// Enable the I2C3 Moudle
I2CMasterEnable(I2C0_BASE);
I2CMasterInitExpClk(I2C0_BASE, SysCtlClockGet(), true);//400Kbps
I2CMasterSlaveAddrSet(I2C0_BASE, 0x44, false);//Specify slave address,Master read from the slave
I2CMasterDataPut(I2C0_BASE,'Q');// Place the character to be sent in the data register
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);// Initiate send of character from Master to Slave
// Delay until transmission completes
while(I2CMasterBusBusy(I2C0_BASE))
{
}
}
