msp430fr2422 i2c 从机发送数据问题

#include <msp430.h>

volatile unsigned char TXData;

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

// Configure GPIO
SYSCFG2 |= USCIBRMP; // remapping configuration
P2SEL1 |= BIT5 | BIT6; // remapped I2C pins

// Disable the GPIO power-on default high-impedance mode to activate
// previously configured port settings
PM5CTL0 &= ~LOCKLPM5;

// Configure USCI_B0 for I2C mode
UCB0CTLW0 = UCSWRST; // Software reset enabled
UCB0CTLW0 |= UCMODE_3 | UCSYNC; // I2C mode, sync mode
UCB0I2COA0 = 0x48 | UCOAEN; // own address is 0x48 + enable
UCB0CTLW0 &= ~UCSWRST; // clear reset register
UCB0IE |= UCTXIE0 | UCSTPIE; // transmit,stop interrupt enable

__bis_SR_register(LPM0_bits | GIE); // Enter LPM0 w/ interrupts
__no_operation();
}

#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_NONE: break; // Vector 0: No interrupts
case USCI_I2C_UCALIFG: break; // Vector 2: ALIFG
case USCI_I2C_UCNACKIFG: break; // Vector 4: NACKIFG
case USCI_I2C_UCSTTIFG: break; // Vector 6: STTIFG
case USCI_I2C_UCSTPIFG: // Vector 8: STPIFG
TXData = 0;
UCB0IFG &= ~UCSTPIFG; // Clear stop condition int flag
break;
case USCI_I2C_UCRXIFG3: break; // Vector 10: RXIFG3
case USCI_I2C_UCTXIFG3: break; // Vector 14: TXIFG3
case USCI_I2C_UCRXIFG2: break; // Vector 16: RXIFG2
case USCI_I2C_UCTXIFG2: break; // Vector 18: TXIFG2
case USCI_I2C_UCRXIFG1: break; // Vector 20: RXIFG1
case USCI_I2C_UCTXIFG1: break; // Vector 22: TXIFG1
case USCI_I2C_UCRXIFG0: break; // Vector 24: RXIFG0
case USCI_I2C_UCTXIFG0:
UCB0TXBUF = TXData++;
break; // Vector 26: TXIFG0
case USCI_I2C_UCBCNTIFG: break; // Vector 28: BCNTIFG
case USCI_I2C_UCCLTOIFG: break; // Vector 30: clock low timeout
case USCI_I2C_UCBIT9IFG: break; // Vector 32: 9th bit
default: break;
}
}

msp430fr2422使用TI i2C 从机程序做测试，发现从机发送数据有问题。主机进行读取操作时，无法正确读取到FR2422从机数据。主机接一个i2c从机，读操作正常。FR2422从机使用FR2422主机测试也是正常。但非2422主机读取2422从机不正确。我看了波形，地址应答后，波形异常，sda一直拉低。